m m -:0i0^'^'Wdmm^i: Kr( CORNELL UNIVERSITY. 7^1 KS I THE THE GIFT OF ROSWELL P FLOWER FOR THE USE OF THE N. Y. STATE VETERINARY COLLEGE 1897 Digitized by Microsoft® CORNELL UNIVERSITY LIBRARY 924 104 226 026 Digitized by Microsoft® This book was digitized by Microsoft Corporation in cooperation witli Cornell University Libraries, 2007. You may use and print this copy in limited quantity for your personal purposes, but may not distribute or provide access to it (or modified or partial versions of it) for revenue-generating or other commercial purposes. Digitized by Microsoft® Digitized by Microsoft® Digitized by Microsoft® DISINFECTION AND DISINFECTANTS A PRACTICAL GUIDE FOR SANITARIANS, HEALTH AND QUARANTINE OFFICERS M. J. ROSENAU, M.D. DIRECTOR OF THE HYGIENIC LABORATORY AND PASSED ASSISTANT SURGEON U. a. PUBLIC HEALTH AND MARINE- H^WTatfe-SJ^VICE, WASHINGTON, D. U. PHILADELPHIA P. BLAKISTON'S SON & CO, I0I2 NVALNUT STREET IQ02 T Digitized by Microsoft® --K » Copyright, igoz, by P. Blakiston's Son & Co. fzA PRESS OF WM. F. FELL A CO., 1220-24 8ANS0M STREET, PHILADELPHIA. Digitized by Microsoft® TO THE MEMORY OF THE OFFICERS OF THE U. S. MARINE-HOSPITAL SERVICE WHO HAVE LAID DOWN THEIR LIVES FIGHTING INFECTION IN ORDER TO PROTECT THEIR FELLOW-MEN Digitized by Microsoft® Digitized by Microsoft® PREFACE. I have made mistakes, and I have seen others make similar mistakes in learning what, how, and when to disinfect. This book has been written with the hope that it may help others who have to battle with the infection of the communicable diseases. I have tried to set down the results of my experience gained in sanitary work of a public health character, both in the field and in the laboratory. The many recent text- books upon bacteriology, hygiene, and sanitary science have been freely consulted. It has been my aim to state the important facts tersely and in a form to be of practical use to the disinfector. Controversies have been avoided, even at the risk of being dogmatic, and upon doubtful points the safer methods have always been given the preference. The subject has been considered from the standpoint of the disinfectant used, the object to be disinfected, and the disease for which the disinfection is done. In con- sidering any subject from three points of view a certain amount of repetition is unavoidable. It is a pleasure to acknowledge the debt I owe to Surgeon- General Walter Wyman, whose aid and encouragement have made this work possible. These pages have been a work of love, and I trust that they may prove a useful and trustworthy guide. September, i<^02. Digitized by Microsoft® Digitized by Microsoft® CONTENTS. Page. Introduction, 17 CHAPTER I. Physical Agents: Sunlight, 33 Electricity, 36 Burning, 37 Dry Heat, 38 Boiling, 41 Steam, 42 CHAPTER II. Gaseous Disinfectants: General Consideration, 83 Formaldehyd Gas, 87 Sulphur Dioxid, 118 Hydrocyanic Acid, 137 Chlorin, 141 Oxygen, 142 Ozone, 143 CHAPTER III. Chemical Solutions: General Considerations, 145 Bichlorid of Mercury, 152 Carbolic Acid, 156 The Cresols, 158 Formalin, 160 Potassium Permanganate, 163 Lime, 164 Chlorinated Lime, 167 The Hypochlorites, 169 Ferrous Sulphate, 170 Zinc Chlorid, 171 Soaps, 172 vii Digitized by Microsoft® VIU CONTENTS. CHAPTER IV. PAGE. Insecticides Applied to Disinfection Against the Insect- borne Diseases: Arsenic, ^^^ Petroleum, ^^'^ Bisulphid of Carbon, ^^^ Pyrethrum, '''^ Sulphur, 1*^ Formaldehyd Gas, ^^^ Hydrocyanic Acid Gas, '" Danyz' Virus and Other Rat Poisons, 188 CHAPTER V. Disinfection op Houses, Ships and Objects, 191 CHAPTER VI. Disinfection for the Communicable Diseases: Typhoid Fever, _ 249 Cholera ' 258 Dysentery, ?^^ Diphtheria, 266 Plague, 274 Tuberculosis, 280 Leprosy, 283 Malaria, 291 Yellow Fever, 296 Filariasis, 302 Pneumonia, 304 Epidemic Cerebro-spinal Meningitis, 311 Smallpox, 312 Chicken-pox, 317 Mumps, 317 Measles 318 Scarlet Fever, 318 Whooping-cough, 319 Influenza, 320 Erysipelas, 323 Dengue, 325 Typhus Fever, 326 Relapsing Fever 327 Glanders, 328 Actinomycosis, 332 Madura Foot, 334 Anthrax, 336 Tetanus, 341 Digitized by Microsoft® LIST OF ILLUSTRATIONS. Fig. Page. 1. Bacteria with Spores (Williams), 18 2. Bacilli of Various Forms {Williams:), 24 3. The Various Arrangements of Micrococci (Williams) 24 4. Spirilla of Various Forms (Williams), 25 5. Common Molds with Their Spores (Williams, after Baum- garten) , 31 6. Hot-air Sterilizer, 39 7. Portable Steam Disinfecting Cylinder, 43 8. Section through an Arnold Steam Sterilizer, 48 9. Arnold Steam Sterilizer, 49 10. Section through Koch Steamer 50 1 1. Koch Steam SteriUzer (Williams), 51 11a. A Combination Sterilizer for Use with Streaming Steam, Boihng Water, or Hot "Water, 51 12. Steam Disinfector of Van Overbeek de Mayer, 53 13. Steam Disinfector of Van Overbeek de Mayer, 54 14. Section through the Van Overbeek de Mayer Steam Disin- fector, 54 15. Section through Autoclave, 56 16. Cross-section through Steam Disinfecting Chamber, 58 17. Longitudinal Section through Steam Disinfecting Chamber, . . 59 18. Kinyoun-Prancis Disinfecting Chamber, 61 19. Steam Disinfecting Chamber, Illustrating the Rectangular Form, 63 20. Kinyoun-Francis Steam Chamber, Showing Improved Qmck- closing Doors, 65 21. Disinfecting Steamer "Sana tor." View in Hold, Showing the Method of Installing the Steam Chambers in a Floating Plant, 67 22. Electric Thermometer 70 23. Automatic Thermometer, 71 24. Pyrometer, 72 ix Digitized by Microsoft® X LIST OF ILLUSTRATIONS. _ Page. Fig. 25. Scheme for InstalHng Electric Thermometer in the Steam Disinfecting Chamber, 26. Plan Showing the Method of InstalUng the Double-ended Steam Chambers at a National Quarantine Station, 73 27. Chart, Showing Automatic Registration of Steaming, 79 28. Example of Sealing Doors, Transoms, or Windows with Gummed Strips of Paper, 85 29. Autoclave for Evolving Formaldehyd Gas under Pressure, . . 94 30. The Same— Portable Type, 94 31. An Autoclave for Evolving Formaldehyd Gas from its Solu- tion under Pressure, 95 32. Trenner-Lee Retort for Evolving Formaldehyd Gas without Pressure 1^^ 33. Trenner-Lee Retort, Showing Compartments, 101 34. The Lentz Formaldehyd Gas Generator, 104 35. Kuhn Formaldehyd Generator or Lamp, 107 36. Formaldehyd Generator. Filling the Lamp, 108 37. Formaldehyd Generator. Lighting the Alcohol, 108 38. Formaldehyd Generator in Operation, 109 39. Formaldehyd Sprinkler, 113 40. Formalin Lamp, 117 41. Formalin Disinfector, 117 42. The Pot Method of Burning Sulphur, 123 43. A. Liquefied Sulphur Dioxid in Tin Cans. B. Sulphur Dioxid in Siphon, 125 44. End View of Sulphur Furnace, 128 45. Longitudinal Section through Sulphur Furnace, 129 46. Double Sulphur Furnace, 131 47. Portable Sulphur Fumigator, Working Side, 133 48. Portable Sulphur Fumigator, Rear Side, 135 49. Portable Sulphur Furnace, 139 50. Apparatus for Spraying Disinfecting Solutions in a Nebulous Spray, 150 51. Apparatus for Spraying Disinfecting Solutions in a Nebulous Spray, 151 52. The Same, Showing Suit Worn by Operator, 152 53. Autoclave for Disinfecting Sputum, 228 54. Typhoid BacilU, Pure Culture, 251 55. Typhoid Colony on Gelatin, 251 56. Typhoid Bacillus with Flagella, 253 57. Typhoid BacilU Invading the Submucous and the Muscular Coats of the Intestines (Baumgarten), 254 Digitized by Microsoft® LIST OF ILLUSTRATIONS. XI Fig. Page. 58. A Stick Culture of the Typhoid Bacillus in Gelatin, 257 59. Spirillum of Cholera 259 60. Involution Forms of the Spirillum of Cholera, 259 61. Colonies of the Spirillum of Cholera after Twenty-four, Forty- eight and Seventy-two Hours' Growth on Gelatin Plates (Curtis), 262 62. Spirillum of Cholera Growing in Gelatin, Showing Lique- faction, 263 63. Amoeba Dysenteriae (after Roos), 266 64. Bacillus diphtherise. Long Beaded Variety with Pointed Ends and the Short Forms, 268 65. Bacillus diphtheriae. Two Specimens of the Medium and Long Varieties with Clubbed Extremities (Curtis), 268 66. Diphtheria Colonies on Agar, 271 67. Diphtheria Bacilli in Pure Culture from Blood-serum (Frankel and Pfeiffer), 271 68. Plague Bacilli in the Scrapings from a Bubo 274 69. Bovine and Human Tubercle Bacillus Growing upon Vege- tables, 281 70. Tubercle Bacilli, Pure Culture 283 71. Tubercle BaciUi in Sputum, 283 72. Surface Appearance of a Colony of the Tubercle Bacilli upon Coagulated Blood-serum, 286 73. Bacillus of Leprosy in Tissue, 289 74. Anopheles punctipennis. Female, with Male Antenna at Right, and Wing Tip Showing Venation at Left (En- larged) (Howard), 293 75. Resting Positions of Culex and Anopheles (Enlarged) (How- ard), 295 76. Stegomyia fasciata, Male (Reed and Carroll) 298 77. Stegomyia fasciata. Female (Reed and Carroll), 298 78. Stegomyia fasciata. Batch of Fifty-two Eggs Deposited by a Single Female (Reed and Carroll), 299 79. Full-grown Larva (Enlarged) (Reed and Carroll), 299 80. Pupa (Enlarged) (Reed and Carroll), 299 81. Stegomyia fasciata. Forty-eight Eggs Deposited in a Close- lying Mass by the Stegomyia fasciata (Enlarged) (Reed and Carroll), 301 82. Newly Deposited Egg of Stegomyia fasciata (Enlarged),. . . . 301 83. The Diplococcus of Pneumonia, Showing Capsules, 305 84. Colony of the Diplococcus of Pneumonia on Gelatin (Frankel and Pfeiffer), - 305 Digitized by Microsoft® XU LIST OF ILLUSTRATIONS. Fig. Page. 85. Friedlander'!5 Bacillus of Pneumonia, 309 86. Diplococcus intracellularis meningitidis in Pus-cells (Council- man), 309 87. Influenza Bacillus (Curtis), 321 88. Influenza Bacillus in Sputum, 322 89. Various Appearances of Streptococci from Bouillon Cultures, . . 324 90. Spirillum of Relapsing Fever, 329 91. Bacillus of Glanders, Showing Irregular Staining, 329 92. Ray-fungus of Actinomycosis. Fresh, Unstained Preparation from a Case of Lumpy-jaw in a Cow. Diagrammatic (Williams), 332 93. Anthrax Bacilli (Baumgarten) , 336 94. Anthrax Bacilli, Showing Spores, , . , 337 95. Anthrax Colony (Baumgarten), 338 96. Tetanus Bacilli, Showing Spores, 342 Appendix, Showing Comparative Scale of Swedish, German and French Thermometers, 345 Digitized by Microsoft® Digitized by Microsoft® Digitized by Microsoft® DISINFECTION AND DISIN- FECTANTS. INTRODUCTION. Disinfection is the destruction of the agents causing infec- tion. An object is said to be infected when contaminated with the living principles — that is, the micro-organisms — causing disease. It is disinfected by destroying these organisms, whether they are in the substance or on the surface of that object. As a matter of fact it is not necessary actually to destroy the infective agents ; it is suflficient to render them incapable of causing or conveying disease. For example, if the micro- organisms are so attenuated that they have lost their viru- lence, or if they are so scattered that they are too few to cause infection, the object of disinfection has been accom- plished. Of course, dilution, attenuation, and the like fortuitous circumstances cannot be depended upon by the disinfector. He must use means that will surely destroy the infectious principles. The only way an infected object may with cer- tainty be rendered safe from the danger of conveying disease is by the intelligent application of physical means or chemical substances which experiment and experience have shown will invariably destroy the__infection. 2 17 Digitized by Microsoft® l8 DISINFECTION AND DISINFECTANTS. The ideal disinfectant is one that destroys the germs without injury to the object. There is no one agent or method applicable to all cases; it is therefore necessary to determine accurately all the conditions, not only of the object to be disinfected, but of the germicide to be used, and to take into account the resistance of the particular morbific principle against which the disinfection is directed. Disinfection, then, deals only with destroying the vitality of those minute forms of life which cause disease ; it does not mean the destruction of all the lower forms of animal and vegetable life that may be upon or in an object — that is sterilization. Fig. I. Bacteria with Spores. — [Williams.) An object is said to be sterilized when all the forms of life contained within it or on its surface are destroyed. All pro- cesses which sterilize are necessarily also disinfectants; but all disinfecting processes by no means cause sterilization. This distinction between disinfection and sterUization arises principally from the fact that some of the micro-or- ganisms have spores, which correspond to the seeds of plants, in being very much more resistant to all the influences which destroy the parent cells. Spores of this character, called endogenous spores, possess to a very high degree the power of resisting desiccation, sunlight, chemical and physical agents which quickly destroy the non-spore-bearing cell. Fortunately, as far as known, none of the pestilential dis- Digitized by Microsoft® INTRODUCTION. 1 9 eases of man, which occur in widespread epidemics, is caused by organisms with resistant spores. Therefore, the usual processes of disinfection, while thoroughly efhcient, may still leave many harmless and hardy bacteria alive. In other words, sterilization is rarely necessary in combating epidemic diseases. Antiseptic substances prevent decomposition and decay. Such substances retard the growth and activity of the micro- organisms, but do not destroy them. There is a great differ- ence between the antiseptic and the disinfecting or germicidal value of a substance. For instance, a solution of formalin will restrain the development of most bacteria in the propor- tion of I to 50,000, but it requires a 3 to 5 per cent, strength of this substance to kill the bacteria in a short time. As weak a solution of bichlorid of mercury as i : 300,000 will restrain the development of anthrax spores, whereas it re- quires a 1 : 1000 solution to destroy them. Saturated solu- tions of salt or sugar will preserve meat or vegetable sub- stances ; that is, they are antiseptic in their action, but not germicidal, as they have small powers of destroying infection. The condition known as asepsis is equivalent to steriliza- tion. Asepsis means the freedom from or the absence of pathogenic micro-organisms. A germicide is a substance or agent which destroys germs. Germicides and disinfectants are interchangeable terms, as they are both used to indicate the destruction of micro- organisms. A substance which has the power to destroy or to neutral- ize the unpleasant odors arising from organic matter under- going fermentation or decomposition is called a deodorant. Such substances must be carefully distinguished from disin- fectants. Deodorants destroy smells, disinfectants destroy germs. A majority of the disinfecting agents are also de- Digitized by Microsoft® 20 DISINFECTION AND DISINFECTANTS. odorants, but all the deodorizing substances are by no means disinfectants. For example, charcoal will absorb the mal- odorous gases arising from putrefying and fermenting materials, but it is inert so far as its power to destroy the cause of these processes is concerned. Formalin, on the other hand, is a true deodorant and disinfectant, as it combines with the organic matter to form new compounds which are both odorless and sterile. Bichlorid of mercury, while a very potent germicide, has but slight immediate effect upon odors. In nature, many forces are constantly at work to destroy infection and thereby limit the spread of the communicable diseases. We should make use of these natural disinfecting agencies by placing objects under the most favorable cir- cumstances for them to exert their maximum effect. These natural influences are chiefly dilution, light, dryness, symbiosis, and heat. Of these agencies, sunlight is the great destroyer of germ life. Few microbes, especially the patho- genic ones, can live in the direct, bright sunlight many hours. Dryness is another condition that is destructive to many of the forms of life with which we have to deal. The combina- tion of dryness and sunlight is almost as good as the gaseous disinfecting processes which are commonly used in actual house disinfection against surface contamination. Dryness, sunlight and cleanliness are the keynotes of sanitary sur- roundings in the modern acceptation of the term. Cleanliness is an important adjunct to the work of dis- infection. The mere act of cleaning removes some of the adherent microbes from the surface, and the ordinary scrub- bing and mopping results in the final destruction of many more. Dry dusting and sweeping only serve to stir up the dust and infection, which disseminate in the air to settle down again upon the same or other surfaces. Digitized by Microsoft® INTRODUCTION. 2 1 Cleanliness accomplishes another important purpose as far as infection is concerned : It removes the organic matter on which and in which the bacteria find favorable conditions for prolonging life and virulence. In the wholesale disinfection which must be practised to check widespread epidemic diseases due to bacterial infection we are largely limited to the use of the agents which nature has constantly at work to destroy such infection. Against a single case of communicable disease, or against a limited infected area, we may employ aggressive measures, such as steam and strong chemicals ; but when a disease due to bac- terial infection has spread over an extensive district, these methods must be supplemented by all the resources of nature. The people must be in prime health to resist the disease. Cleanliness must be more scrupulously practised than ever in order that organic filth may not be present to afford a favor- able soil for the life, growth and dissemination of the in- fective agents. Sunlight and dryness must be given their fullest opportunity to operate, even at the expense of a few faded carpets or colors. Many of the pathogenic micro-organisms are destroyed by the processes of putrefaction and fermentation of organic matter. They die in the fierce struggle for existence going on in these destructive processes. For the most part, the hardier saprophytic forms of life overpower and kill the dis- ease-producing microbes, which have comparatively feeble powers of resistance. The fact that infected carcasses, sewage and putrid organic matter largely purify themselves by the very processes that destroy them is a fortunate provision of nature. With the advent and advance of the science of bacteri- ology the practice of disinfection was directed against the destruction of bacteria wherever they were found — in the Digitized by Microsoft® 2 2 DISINFECTION AND DISINFECTANTS. air, the soil, the water, on clothing and fabrics, or about the patient and his discharges. But with the advance in our knowledge of disease, and especially with the knowledge that disease germs are frequently conveyed from the sick to the well through the agency of other animals, disinfection has come to include the destruction of vermin and insect pests. In disinfecting for malaria, yellow fever and filariasis, we must destroy the mosquitos which convey the infection. In disinfecting for cholera, typhoid fever and other diseases, we must pay attention to the flies and other winged insects which have been in contact with the infected discharges. In the disinfection for plague, we must destroy the infected rats, mice and fleas. In fact, as our knowledge of the subject increases we find that domestic animals and vermin are playing a very con- spicuous r61e in the transmission of disease. So dangerous do we now know that the fly and mosquito may be, that when the matter is more generally understood it should be a greater reproach to the housewife to have these danger- ous vermin in the household than to have bedbugs. It naturally suggests itself that it is much better to prevent infection than to be compelled to destroy it after it has become disseminated through ignorance, carelessness or negligence. It is the duty of the disinfector to destroy infection wher- ever it is found. It is the duty of the sanitarian to prevent and avoid infection. For instance, in the case of cholera the sanitarian protects the water-supply, but if it becomes contaminated the disinfector must know how to render it safe. In the case of diseases due to animal parasites and conveyed by insects, the disinfector must know how to de- stroy the infected insects. It is the sanitarian's province to institute measures looking to the extermination of the Digitized by Microsoft® INTRODUCTION. 23 insects or to the protection of the individuals against their bites. The best way to apply disinfection is at the seat of origin of the infection. This means the inunction of the skin in the case of the exanthemata ; the destruction of the specific poisons in the stools and urine of typhoid fever, cholera and dysentery; the boiling or burning of the sputum of tuberculous patients; and strict measures applied to each case which will prevent the dissemination of the pathogenic germs from the body in live and virulent form. When proper precautionary measures have been taken at the bedside with a case of cholera, typhoid fever, plague, or the like infectious diseases, there is little need of sub- sequently disinfecting the sick-room. But when due to carelessness or lack of precaution, the result of ignorance, a general diffusion of the infection results, then a general disinfection becomes necessary. It is the province of the disinfector to know how best to deal with such conditions, so as to render them harmless. The disinfection of any given place is a complex opera- tion, and should not be attempted by any one not familiar with the peculiarities of the particular infection with which he has to deal, and not possessing a thorough knowledge of the disinfecting agents employed. Fortunately, most of the germs which cause the communicable diseases in man are non-spore-bearing micro-organisms. They are therefore comparatively easy to eradicate by disinfection. Spores possess very great resisting powers against all our disinfect- ing agents, and are much more difficult to kill than the micro-organisms themselves. For example, almost all bacteria may be killed by drying alone, by which, generally speaking, spores are little influenced. As a rule the bacilli are less resistant than micrococci, Digitized by Microsoft® 24 DISINFECTION AND DISINFECTANTS. and the vibrios are less resistant than either the bacilli or the micrococci. Individual bacteria from the same culture vary in their vitality, just as one member of a family is stronger than another. Geppert* has shown that spores from the same spore-bearing bacillus have very different powers of resistance. This fact has a practical bearing in Fig. 2. Bacilli of Various Forms. — [IVilHams.) drawing conclusions from laboratory experiments as to the effect and value of germicidal agents in actual practice. It also explains, in part, the discrepancies as to the times of exposure and the strengths of solutions necessary to accom- plish disinfection, as stated by different experimenters. Fig. 3. •^ ^ /T •»''*••''• ft The Various Arrangements of Micrococci. — {WilHams.) The communicable diseases are by no means all due to bacteria. A very large and important class of these affec- tions is due to animal parasites. Bacteria are the lowest forms of vegetable life. They are minute microscopic cells, very variable in shape. Round ones are called cocci; those shaped like a rod, bacilli; and *" Berliner Idin. Wochenschrift," 1889, No. 36, p. 791 ; also 1890, No. 12, p. 27. Digitized by Microsoft® INTRODUCTION. 25 the curved and corkscrew-shaped ones are called vibrios or spirilla. Many of them have independent motion. All bacteria multiply by a simple process of division or fission. Some of them have spores. They all require moisture for their development, and grow best upon organic substances. For a full account of bacteria and their products it will be necessary to refer to one of the many excellent works upon this subject. Many kinds of animal parasites cause disease in man. By far the most important is the group of protozoa, which resemble the bacteria only in being minute microscopic cells with independent motion. In other respects they have Fig. 4. -V \l dy ''»'ia~~ Spirilla of Various Forms. — {Williams.) all the functions of animal life. They multiply both by direct division, similar to the asexual fission of bacteria, and by a sexual union. Some of the animal parasites have spores, but not of the same high degree of resistance as the endogenous spores of bacteria. The animal parasites of man are usually communicated from the sick to the well through an intermediate host. A distinction is often drawn between the "contagious" and the "infectious" diseases. These terms have always lacked scientific precision, and have been the source of some confusion. The word "communicable" is a much better term for all the diseases of this class, and has been given the preference in this work. Digitized by Microsoft® 26 DISINFECTION AND DISINFECTANTS. In the old acceptation of the word, a contagious disease was one that was "catching" by contact between the sick and the well. It was believed that the contagion was thrown off in the exhaled breath and contaminated the atmosphere surrounding the patient. With the possible exception of smallpox, and typhus fever when it prevails in epidemic form, there are few contagious diseases according to this meaning of the term. An infectious disease, on the other hand, is one spread from the sick to the well in an indirect manner. The in- fective agent contaminates the water, food-supply, or other object, through which means the disease is communicated to well persons who in no way come in contact with the sick. These distinctions are entirely artificial and serve no useful purpose. Almost every one of the communicable diseases may be transmitted from the sick to the sound in a great variety of ways. In the light of our present knowl- edge it is not practicable to classify this group of diseases according to their methods of propagation, and it is there- fore preferable to speak of them under one heading. In the body the immunity or resistance to disease is an active protection to the individual, and may act as a check to the spread of infection; on the other hand, such individuals often spread the contagion of pestilential affections. Almost every one of the great epidemic diseases may present itself in so mild or latent a form that neither the individual nor his associates suspect that in his system he is harboring the infective principles and spreading the contagion to others. For instance, many persons have the bacillus of diphtheria in their mouths without suffering any local or general symptoms. Such persons may spread this infec- tious disease by kissing, by using cups, spoons, etc., which are shortly thereafter placed in the mouths of others more Digitized by Microsoft® INTRODUCTION. 27 susceptible to this micro-organism and who thereby con- tract a severe or fatal type of diphtheria. Similarly, many persons have tuberculosis a long time before they suspect it, and may spread it in a similar manner. There are cases of cholera so mild that it cannot be recognized except by bacteriologic examination; in truth, the virulent, live cholera vibrio may exist in great numbers in the intestinal canals of apparently healthy individuals. The dejecta from such a person might unwittingly be permitted to con- taminate the water-supply of a large city, resulting in a serious epidemic. It is well known that yellow fever may occur in very mild form, — very difficult to recognize, — and it is doubtless just such cases that are the spark to kindle an epidemic. As clearly defined a disease as smallpox may be so mild that the patient has only a few pustules, with very slight con- stitutional disturbances. Walking cases of typhoid fever are not uncommon. Such cases are difficult to recognize. The same may be said of practically all the known com- municable diseases. The belief is growing stronger that the communicable dis- eases are more often spread through the intermediation of these mild, latent and unrecognized cases than through the agency of fomites — that is, inanimate objects. It has long been well known that disease may be communicated from the sick to the well by a third person, and it was formerly supposed that this was always the result of the infection clinging to the clothing, hair, etc., of the person; but we now know that it may also be due to the infection growing in the body of the individual. Diphtheria is a well- known instance of the conveyance of infection by both of these methods. The diphtheria bacillus may be growing in the secretions of the throat of the individual, or may Digitized by Microsoft® 28 DISINFECTION AND DISINFECTANTS. remain alive and virulent attached to his clothing or to some other object about his person. When disease recurs in a house, we must not be too quick to blame the disinfector or the methods used by him, for frequently the infection lurks on the persons of the inmates of the house, rather than in the furnishings and contents of the rooms. We know the part played by inanimate things in the trans- mission of some of the communicable diseases, but as our knowledge of the subject increases, their importance di- minishes. As Dr. J. H. White tersely expresses it, "Infec- tion is more often conveyed from place to place in a pair of shoes than on the clothing or in the baggage of the person." The disinfector must therefore know the best methods of purifying rooms, theaters, cars, meeting-places, schools, barracks and other places where many persons assemble and where latent, mild, or unrecognized cases are constantly suspected or are actually occurring to contaminate the surroundings. There is no accurate standard by which the power of dis- infecting agents may be measured. There are conditions influencing the life of the bacterial cell which we are unable to control. It is for this reason that the strengths of solu- tions necessary to disinfect are variously stated by different authorities, and the time of exposure is, for the same reason, not always definitely decided. The difficulty in this con- nection is to determine the minimum conditions which will furnish trustworthy results and still provide that excess necessary for general practice, or what bridge-buUders call the "coefiicient of safety." While the results of the scientific work in the laboratory must be our guide as to the value and efficiency of any disinfecting process, we cannot ignore the results of ex- Digitized by Microsoft® INTRODUCTION. 29 perience gained in actual practice in combating the com- municable diseases. This is especially true of disinfectants used against diseases the cause of which is only surmised, or the mode of transmission not definitely known. We have recently had a lesson on this point in the case of sulphur. This substance had long been used as a disinfectant for yellow fever, and practical experience had justified the confidence placed in sulphur fumigation to check the spread of this disease. But when the scientific tests made in the laboratory showed that sulphur dioxid lacks the power of destroying resisting spores, great discredit was thrown upon it. But now we know that yellow fever is transmitted through the agency of the mosquito, and with the well- known insecticidal powers of sulphur dioxid confidence has been restored both as to the scientific and the practical value of this substance. On the other hand, laboratory experiments have estab- lished with great accuracy the value and reliability of certain substances which otherwise would have gone begging. Some substances, such as zinc chlorid and sulphate of iron, have been robbed of the high value in which they were formerly held, and placed near the bottom of the list of disinfectants. Even carbolic acid, which at one time was so highly prized, has been shown to have less germicidal power than was supposed. The success of the disinfector lies in personal attention to the minute details. Germs are little things, and it is the little things that count in this kind of work. The dis- infector who is satisfied to leave the process in the hands of an inexperienced person, with a few words of instruction, cannot expect to obtain trustworthy results. In no other work is the watchword that ' 'vigilance is the price of success " truer. The disinfector must give personal surveillance Digitized by Microsoft® 30 DISINFECTION AND DISINFECTANTS. to the whole process — the materials, the strength of solutions, modes of application — and must be present to guide and direct every step of the operation, with the same conscientiousness and thoroughness with which the surgeon assures himself of every detail of asepsis in his operating room. It is true that the means and methods employed to rid a room of infection closely resemble those used in the operat- ing room, but it stands to reason that in the former case they can rarely be carried out with the same exactness and certainty as in the latter, where everything is constructed and arranged with this end in view. In the surgical clinic nothing short of sterilization is safe, while in the great majority of the disinfection done to prevent the spread of epidemic disease, measures that fall far short of steriliza- tion will suffice. For instance, in the fumigation of a room against plague, tuberculosis, typhoid fever, cholera, and the like diseases due to non-spore-bearing organisms, it is im- material if the dust on the ledges contain living subtilis and spores of the common moulds found in the air, or other hardy saprophytic forms of life, so long as the pathogenic bacilli are dead. A great deal may be learned by a thorough inspection. To be sure, we cannot see the germs with our unaided vision, but we can see the dirt and moisture and other conditions that present a favorable medium for the growth and multi- plication of the pathogenic micro-organisms. While the old idea that filth and unsanitary conditions breed disease, de novo, is wrong, it is nevertheless true that these conditions keep the infectious principles alive and favor their propa- gation. It is therefore plainly the duty of the disinfector not only to destroy the actual infection, but also to eradicate all the conditions that would act as breeding-places and disseminators of infection. Digitized by Microsoft® Fig. 5. Common Molds with Their Spores. — [Williams, after Baumgarten.) a. Penicillium glaucum. b. Oidium lactis. t. Aspergillus glaucus. d. The same more highly magnified, e. Mucor mucedo. 31 Digitized by Microsoft® 32 DISINFECTION AND DISINFECTANTS. The disinfection of rooms, baggage, ships, and objects that have been exposed to infection must of necessity be greatly in excess of the actual requirements. This is one of the difficulties met with in attacking an invisible foe. A room might readily be disinfected and rendered safe by applying a few gills of one of the germicidal solutions to a small spot or a limited area ; but as we cannot see the germs, it is necessary to apply our disinfecting agents to every inch of surface of the room and all its contents, in order not to miss that particular infected spot. As our knowledge of infection becomes more exact, our processes of disinfection become more precise. At first disinfection was directed by a shotgun process, in a general sort of blunderbuss way, against everything; but now that we know the habits and habitat of each one of the particular micro-organisms, we can concentrate our efforts with more exactness upon the particular object or media liable to infection, with every assurance of eradicating the danger. In other words, it is quite as important to know what to disinfect as how to disinfect, and a very thorough knowl- edge of the subject of the causes and modes of transmission of the communicable diseases is the most useful weapon the disinf ector has in his fight against the spread of infection. The stress of modern activities demands disinfecting pro- cesses that are instantaneous in their action, all-pervading in their effects, cheap, harmless, and free from any un- pleasant odors that might offend the senses of the fastidious. Such perfect disinfectants are not known. It requires time, money and the expenditure of well-directed and intelligent energy to accomplish satisfactory disinfection. Digitized by Microsoft® CHAPTER I. PHYSICAL AGENTS. Sunlight — Electricity — Burning — Dry Heat - — Boiling — Steam. Sunlight is an active germicide. It de- SuNLiGHT. stroys spores as well as bacteria. The importance of the sun's rays in destroying or preventing the development and growth of micro-organ- isms in nature cannot be overestimated. Unfortunately, the sunshine is so uncertain, and the force of the sun's rays so variable and their disinfecting power so superficial, that it cannot be depended upon as an aggres- sive measure in attacking infection in rooms, ships and confined spaces. Sunshine comes more under the purview of the sanitarian than under that of the disinfector, but the latter can always use it to advantage in supplementing his other methods, especially in out-of-the-way localities. Rooms and objects may always be sunned and aired with advantage after dis- infection. The different rays of light have very different effects upon germ life. The blue, violet, and ultra-violets — that is, the more refrangible chemical rays of the spectrum — are the only ones possessing germicidal power. The red and yellow rays are practically inert in this regard. The nature of the source of light seems to have little in- fluence upon the result, it being more a question of intensity. 3 33 Digitized by Microsoft® 34 DISINFECTION AND DISINFECTANTS. Even diffused light retards the growth and development of micro-organisms, and if strong enough may finally kill them. Electric light is also effective, but in a much diminished degree. The Rontgen rays (X-rays) have no bactericidal properties. The time required for the light to arrest the multiplica- tion and to cause the death of the different germs is far from being definitely fixed. There are many conditions besides the brightness of the light, such as moisture, temperature, the transparency, composition, thickness of the media, etc., to aid or hinder the effect of the rays. The time also varies with the different micro-organisms. The germs of plague and cholera die more quickly than those of tuberculosis. Spores are much more resistant to the influence of the sun's rays than the bacterial cells themselves. For example, it usually requires about thirty hours' sunning to kill an anthrax spore, while the anthrax bacillus is killed in one or two hours under the same conditions. On account of all these facts, the published figures upon the time required to destroy germs in the sun have only a relative value. A few instances are given to illustrate the time required for the sunlight to destroy some of the more important pathogenic bacteria: Buchner and Mink * found that it required an insolation of one hour to sterilize a water containing a suspension of B. coli communis. Pansini f has observed the sun kill the Bacillus anthracis in cultures of bouillon in from one to two and a half hours. The moist spores died in from one-half to two hours, and the dried spores in from six to eight hours. * Buchner, " Ueber den Einfluss des Lichtes auf Bacterien," " Centralbl. fiir Bakt.," XII, 1893. f E. Mace, "Traits Pratique de Bacteriologie, " Paris, 1901, p. 82. Digitized by Microsoft® PHYSICAL AGENTS. 35 Janowsky * states that the typhoid bacillus resists about six hours' exposure to sun. ]vedoux-Lebard t reports that the bacillus of diphtheria exposed dry and in a very thin film to diffused light is killed in twenty -four hours. According to Koch and Migneco,t the tubercle bacillus commences to lose its virulence after three hours' exposure to sunlight, and is often killed in five to seven hours, de- pending upon the thickness of the layer of the material in which it is exposed. Rosenau § found that the plague bacillus exposed to the direct action of the sunlight dies in half an hour, provided that the temperature in the sun is above ^o^ C. The higher the temperature, the more energetic is the action of the sunlight. The effect of moisture is somewhat peculiar. Dry spores live much longer in the sunlight than moist ones, whereas it is well known that desiccation hastens the death of the bacteria themselves. Before killing them, the sun's rays often attenuate the virulence of bacteria. The effect of the sunlight, at best, is very superficial upon opaque objects. In clear solutions or water it penetrates some distance. Just how the light kills is difficult to explain satisfactorily. That the action is chemical seems likely from the fact that it is the ultra-violet rays of the spectrum that are endowed t with this power. * Janowsky, " Zur Biologie der Typhusbacillen," " Centralbl. fur Bakt. ," VIII, 1890. t Ledoux-Lebard, "Action de la luminere sur le bacille diphtherique, " "Arch. deM6d. Exper.," 1893. J Migneco, " Azione della luce solare suUa virulenza dello bacillo tuber- culare," " Anali d'Igine sperimentale, " V, 1895. § Rosenau, " The Viability of the Bacillus Pestis," Bulletin No. 4, of the Hygienic Laboratory, Marine Hospital Service. Digitized by Microsoft® 36 DISINFECTION AND DISINFECTANTS. N Downes and Blunt* empHasize the importance of free oxygen in the influence of light upon bacteria. They state that without the presence of free oxygen light seems to have no germicidal power. Richardson, t and also Dieudonne, J showed that in cul- tures of bacteria the light in the presence of water and oxy- gen causes a production of hydrogen peroxid, which is well known to have strong disinfecting powers. The recent work of Novy indicates that organic hyper- oxids are produced under certain circumstances in fluids by the action of the sun's rays. These hyperoxids, especially acetozone, have been shown to be among the strongest germicidal substances known. All the workers in this line agree upon the strong germi- cidal power of the sun's rays, and its importance in nature ; but, unfortunately, the laboratory results can only be used to a limited extent by the disinfector in his practical work. The disinfecting power of the sunlight exerts its effects only upon the surfaces exposed directly to the light, and even here the results are apt to be unequal, as Esmarch pointed out. This is easy to understand when we recall how many circumstances may modify this power of the solar rays. The action of electricity on bacterial life EivSCTRiciTY. has been studied by various experimenters, who have arrived at contradictory results. Some very extravagant claims have been made for the effect of the various electric currents, but recent work has shown these claims to have been founded on error. It ap- pears that electric currents have little germicidal action in * " Proceedings of the Roy. Soc. of London," vol. xxvi. f "Jour. Chem. Soc.," 1893, i, 1109-1130. J"Arb. aus. d. kais. Ges.-Amte," Bd. ix, 1894. Digitized by Microsoft® PHYSICAL AGENTS. 37 themselves, and that the apparent effects are due either to the heat generated by the current or to electrolytic action. Electricity has very little use in practice as a disinfectant. Hermite * used the product of electrolysis for the steriliza- tion of sewage. He added sea-water (sodium chlorid) to the sewage, and the electrolytic action caused the formation of hypochlorite, which has well-known germicidal action. Webster f adds chlorids to sewage and uses iron plates as electrodes, with the result that ferrohydroxid is produced by electrolysis. It is evident, as pointed out by Zeit, that it would be simpler to add the hypochlorite or the ferro- hydroxid directly to the sewage. In other words, the effect of electrical currents upon bac- teria seems to be a purely chemical one, in the case of anti- septic substances being formed by electrolytic decomposi- tion ; or a thermal one in the case of the production of heat which so frequently attends the discharge of electric currents. Rontgen or X-rays have no direct bactericidal properties. The clinical results obtained by these electric discharges must find their explanation in other factors, possibly the production of ozone, hypochlorous acid, organic hyper- oxids, necrosis of the deeper layers of the skin or phago- cytosis. Fire is the great purifier. Burning has. Burning. however, a very limited range of usefulness in practical disinfection. A disinfector is seldom justified in burning an article against the wish of its owner, for we now possess other methods by which any *F. Robert Zeit, " Effect of Direct, Alternating, and Tesla Currents and X-rays on Bacteria," "Jour. Amer. Med. Assoc," Nov. 30, 1901. f'Jour. Soc. Cliem. Ind.,"p. 1093; "Jour. Amer. Med. Assoc," Nov. 30, 1901, p. 1432. Digitized by Microsoft® 38 DISINFECTION AND DISINFECTANTS. object may be rendered safe so far as its power of conveying disease is concerned. In actual practice, however, the dis- infector comes across a great mass of rubbish and articles of little value, that he will find safer and cheaper to burn than to disinfect. The burning of garbage and refuse is the safest means of disposing of these substances from a sanitary standpoint, especially in districts where pestilential disease prevails. From the same standpoint the cremation of bodies dead of a communicable disease is by far the safest means of pre- venting the spread of infection from this source. The burn- ing of garbage and refuse requires special furnaces, if large amounts are to be dealt with. Small amounts may effec- tively be disposed of by an improvised fire of coal, wood, or petroleum. A temperature of 150° C, continued for Dry Heat, one hour, will destroy all forms of life, even the most resisting spores. It is easy to maintain this temperature in an apparatus of special con- struction known as a hot-air or dry-wall sterilizer. Glass- ware and many objects that will stand this degree of heat are sterilized in an oven of this kind in bacteriologic labora- tories and in surgical clinics. A dry heat somewhat less than 150° C. is sufficient to destroy many pathogenic bacteria, especially the non-spore- bearing variety, such as plague, cholera, diphtheria, tuber- culosis, pneumonia, and most of the epidemic diseases to which man is liable. Dry heat is not so reliable a disin- fectant as moist heat, especially as it lacks penetration, and is injurious to fabrics. Most materials will bear a temperature of 110° C. (about 230° F.) without much injury, but when this temperature is Digitized by Microsoft® Fig. 6. Hot-air Sterilizer. Digitized by Microsoft® Digitized by Microsoft® PHYSICAL AGENTS. 41 exceeded, signs of damage soon begin to show. Scorching occurs sooner in woolen materials, such as flannels and blankets, than with cotton and linen. The overdrying renders most fabrics very brittle, but this injury may be lessened by allowing the materials which have been sub- jected to dry heat to remain in the air long enough to re- gain their natural degree of moisture before manipulating them. The ordinary household cooking oven is as good as any specially contrived apparatus for the disinfection of small objects by dry heat. In the absence of a thermometer it is usual to heat the oven to a point slightly below the tem- perature necessary to brown cotton, and expose the objects no less than one hour. Dry heat fixes many stains, so that they will not wash out. This is especially marked with albuminous materials coagulable by heat, and the method should not be used for the disinfection of fabrics and objects soiled with blood, sputum, excreta, or similar substances. Boiling is such a commonplace, everyday Boiling. process that it is often neglected in practical disinfection, despite the fact that it is one of the readiest and most effective methods of destroying infection of all kinds. An exposure to boiling water at 100° C, continued half an hour, will destroy the living prin- ciples of all the known infectious diseases, even very resisting spores. To be sure, there are a few spores that have shown a remarkable resistance to boiling water and streaming steam in laboratory experiments, but these are exceptions, and may be disregarded in practical work. In fact, a degree of moist heat much lower than the boiling-point of water is effective against the great majority of known infectious Digitized by Microsoft® 42 DISINFECTION AND DISINFECTANTS. agents. A temperature of 70° C. will destroy within half an hour the germs of cholera, diphtheria, plague, tuberculosis, typhoid fever, pneumonia, erysipelas, and practically all the diseases due to non-spore-bearing bacteria. Boiling kills these bacteria at once. To destroy the infection of anthrax, tetanus and other sporulating bacteria, two hours' exposure to moist heat at 100° C. is essential. Boiling is particularly applicable to the disinfection of bedding, body linen, towels and fabrics of many kinds; to kitchen- and tableware; to cuspidors, urinals and a great variety of objects. Surfaces, such as floors, walls, beds, furniture, etc., may be effectively disinfected by mechani- cally cleansing them with boiling water. The efficacy of boiling water, especially when used under such circum- stances, is greatly increased by the addition of corrosive sublimate, carbolic acid, or any one of the soluble germicidal agents. The addition of lye, borax, or a strong alkaline soap greatly increases the penetrating power of boiling water, when applied to surfaces soiled with organic or oleaginous matters. In using boiling water for the disinfection of bright steel objects or cutting instruments, the addition of i per cent, of an alkaline substance (bicarbonate of soda) will prevent rusting and injury to the cutting edge. Steam is the most valuable disinfecting Steam. agent we possess. It is reliable, quick, and may be depended upon to penetrate deeply. It does more than disinfect ; it sterilizes. Bacteria are killed instantly, spores are killed in a few minutes, and it may therefore be used to destroy the infection of any one of the communicable diseases. Digitized by Microsoft® Digitized by Microsoft® Digitized by Microsoft® PHYSICAL AGENTS. 45 Either streaming steam or steam under pressure is used in practical disinfection. Streaming steam has the same disinfecting power as boiling water, and an exposure of half an hour is sufficient to kill very resistant spores. Steam under pressure is a more powerful germicide than streaming steam. At a pressure of 15 pounds to the square inch steam has a temperature of approximately 120° C, and will surely sterilize in twenty minutes. At 20 pounds pressure it has a temperature of approximately 125° C, and will sterilize in fifteen minutes. For the disinfection of bedding, clothing, fabrics of all kinds, and a great variety of other objects, steam is appli- cable and does no particular harm, provided the precautions described more in detail under each method are taken. Steam is very apt to shrink woolens and injure silk fabrics. It ruins leather, fur, skins of all kinds, also rubber shoes, mackintoshes, and similar articles made of impure rubber. It is important, in disinfecting with steam, whether with streaming steam or steam under pressure, to expel the air from the apparatus, for the air, being a poor conductor of heat, forms dead spaces and prevents the steam from coming in direct contact with the articles to be disinfected, thereby defeating the object to be attained. As steam is lighter than air, the latter can best be expelled from the apparatus or inclosiure by admitting the steam from above, in which case the descending column of steam forces the air out at the bottom. If the steam is admitted from the bottom, it swirls up, making a nearly uniform mixture with the air, and while the temperature quickly rises throughout the inclosure, the air escapes mixed with the steam, so that it takes a very long time and an unnecessary waste of steam to drive out the contained air. 4 Digitized by Microsoft® 46 DISINFECTION AND DISINFECTANTS. In streaming steam we have an efficient Streaming and absolutely reliable disinfecting agent for Steam. many practical purposes. In the laboratory and the surgical clinic it is used in the Arnold steam sterilizer and the Koch steamer. It is also used on an extensive scale in specially devised apparatus in many of the large disinfecting establishments in Germany. Bacteria are killed almost instantly by exposing them directly to streaming steam; however, allowance must be made for the time it takes for the steam to penetrate and heat the object to ioo° C, so that it is usual to leave them in the steam sterilizer one hour. The time required to heat the ap- paratus itself must, of course, always be taken into account. Spores are occasionally found that resist several hours' steaming. Such instances are not only exceptional, but are in almost all cases the spores of non-pathogenic bacteria. For example, Globig* found spores of a particular variety of the hay bacillus that required five and a half to six hours' exposure to streaming steam at a temperature of ioo° C. in order to kill them. And Christen f isolated a bacillus of the same variety whose spores withstood i6 hours' exposure to streaming steam at ioo° C. It is fortunate that instances of such highly resistant spores are exceptional, and it is also for- tunate that the great majority of the communicable diseases from which man suffers are due to non-spore-bearing bacteria. In using streaming steam for the disinfection of such dis- eases as anthrax, tetanus, malignant edema, symptomatic anthrax, the gas-producing anaerobes, and other spore- bearing infections, it is necessary to prolong the exposure to not less than two hours after the temperature reaches ioo° C. *"Zeitsclir. fur Hygiene," Bd. Ill, 1887, p. 333. f'Mittheil. ii. d. klin. u. mad. Inst. d. Schweiz," in, Heft 2, 1895. Digitized by Microsoft® PHYSICAL AGENTS. 47 Disinfection with streaming steam may be accomplished in many ways without the use of special apparatus. For rough-and-ready work on the railroad the objects to be dis- infected may be hung up in a freight car and the steam brought from the locomotive. On board a vessel one of the compartments above the water line may be filled with steam from the boiler. Fabrics and objects may be disinfected in any rough structure wherever a boiler is found to furnish the steam. Such a structure need not be tight, for the streaming steam escaping from the cracks produces a circulation and favors penetration. In the household, small objects, body and bed linen, and other fabrics may be thoroughly disinfected by streaming steam by placing a large pot or wash-boiler on the kitchen fire, and arranging broom handles across the top to hold the materials to be disinfected. The whole should be covered with a sheet or cloth to retain the heat, and steamed for an hour or longer, depending upon the degree of penetration required and the energy with which the water boils . The addition of some salt to the water will raise the boiling- point, and the steam wUl therefore be given off at a higher temperature than ioo° C, which is a distinct advantage. The Arnold steam sterilizer is the best and The most economic instrument of its kind for the Arnold Steam disinfection of small objects by streaming SteriIvIZER. steam, without pressure. This form of ap- paratus depends upon the heating of a small amount of water, which descends through the apertures (A), and which rises as steam into the sterilizing chamber (B), where it condenses, to fall back into the pan (C). The water in the pan (C) soon becomes hot, so that a great saving in Digitized by Microsoft® 48 DISINFECTION AND DISINFECTANTS. time and fuel is effected. This form of sterilizer, as ordin- arily sold on the market, is opened by removing the hood and lid, which should be done as soon as the process is com- pleted, in order to prevent the accumulated steam in the chamber condensing upon and wetting the exposed objects. Fig. 8. Section through an Arnold Steam Sterilizer. The sterilizer may be heated on the kitchen fire, or over a gas flame or oU lamp, comparatively little heat being re- quired. An improved form of the Arnold steam sterilizer, known as the Boston Board of Health pattern, is a much more con- Digitized by Microsoft® PHYSICAL AGENTS. 49 venient design than the older form of apparatus with the hood. As will be seen from the accompanying illustration, this sterilizer has two doors opening on the side, one in the hood and the other in the sterilizing chamber itself. Fig. 9. Arnold Steam Sterilizer. The Koch steamer is an apparatus de- ThB Koch signed for the disinfection of objects in Steamer. streaming steam without pressure. It con- sists simply of a metal vessel, usually made cylindric in shape, and covered with felt or some non-absorb- ent material. The steamer is furnished with a water gage (R, Fig. 10) and faucet, and a thermometer (th). The lid (D) is also covered with felt and does not fit hermetically. Digitized by Microsoft® 5° DISINFECTION AND DISINFECTANTS. or has a small opening so that the steam may escape, which favors the circulation and penetration, and prevents the pressure rising. The steamer is partly filled— about one- third— with water, as shown on the diagram (Fig. lo), and the heat is applied to the bottom of the kettle by means of a Bunsen gas burner or any other form of flame, sufficiently hot to boil the water energetically. Fig. io. Section through Koch Steamer. The articles to be disinfected are placed on a special carrier that fits in the cylinder above the water, or they may be hung in by cords from the hooks {H). While this form of disinfector is commonly small in size for laboratory work, it is also built on a scale sufficient to hold mattresses, bedding, and clothing, and may be used for the disinfection of baggage upon a large scale. In the larger sizes it is advisable to use a solution of salt, in order Digitized by Microsoft® IMU. II. KricH Steam Steriliser.— (Tv-cw IVilliauis.) Kii;. iiA. .,, c.,.rRm7ER FOR Use ^\ITH Streaming Steam, Eoilinc A COMI'.INATION SIEKIIT-^LR ' '"" J^ y WATER \\ATER, or llOl WATER. Digitized by Microsoft® Digitized by Microsoft® PHYSICAL AGENTS. 53 to insure the streaming steam at the exit having a tempera- ture of 1 00° C. As the steam cannot escape freely, and as the loss by heat is guarded against, a uniform temperature of 100° C. may be obtained from the surface of the water to the lid ; and as the lid is not tight, the pressure does not rise. Fig. 12. Water g^ Insulating: W^ material Course of the steam Steam Disinfector of Van Overbeek de Mayer. The Koch steamer is an efficient and economic method of disinfection, although it is more cumbersome, requires more fuel, and takes a longer time to heat than the vVrnold steam sterilizer. A good form of apparatus depending upon streaming steam as its disinfecting agent has been designed by Dr. G. Digitized by Microsoft® 54 DISINFECTION AND DISINFECTANTS. Van Overbeek de Mayer. This steamer is applicable for the disinfection of bedding and baggage in quantities, for which purpose it is made in large sizes. The principles of construc- tion and action are shown on the accompanying diagram (Fig. 12). The water is heated by a coal or wood fire, and the steam rises as shown by the arrows, to enter the top of the chamber at F. From here it descends, displacing the air, and flowing through the objects exposed in the chamber A, finally escap- FiG. 13. Fig. 14. ing at the outlet G. The steam is prevented from condensing in the outlet pipe, H, by the hot water which surrounds it, until it escapes into the stack, L. A modified form of this apparatus, designed by Merk, is shown in the accompanying illustrations, figures 13 and 14. Steam under pressure, or superheated Stbam under steam, acts more rapidly and penetrates Pressure, more deeply than streaming steam at 100" C. Steam at a pressure of one atmosphere, Digitized by Microsoft® PHYSICAL AGENTS. 55 or temperature of 120° C, will sterilize with certainty in fifteen minutes' time. At a temperature of 115° C. it may- be depended upon to sterilize in twenty minutes. The following table, according to Globig,* shows graphically the increased power of steam under pressure, upon an excep- tionally resistant subtilis spore: In streaming steam at 100° C, subtilis spore killed in 5^ to 6 hours. In steam under pressure at I09°-II3° C, subtilis spore alive after 45 minutes. Ii3°-ii6° C, II2°-I23° C, 126° C, 127° C, killed in 25 10 3 2 immediately. 130° C, " Superheated steam is very useful in the laboratory and the surgical clinic to obtain absolute sterilization in a much shorter time than is possible with streaming steam. On account of the great certainty with which steam under pres- sure acts it is a favorite method in practical disinfection, and apparatus for applying this process on a large scale have reached a high degree of perfection. The smaller forms of apparatus are known as digesters, or autoclaves, the larger ones as steam disinfecting chambers or cylinders. The autoclave, digester, or steam pressure ThS sterilizer consists of a kettle usually made of Autoclave, copper and sufficiently strong to withstand the pressure. Water is placed in the kettle and the heat is applied to the bottom, usually by means of several Bunsen gas jets. The apparatus is surrounded as high as the shoulder, where the lid is attached, by a metal jacket which serves the purpose of bringing the heat of the flame in contact with the entire surface of the kettle. The * "Zeitschr. fur Hygiene," Bd. ni, 1887, p. 331. Digitized by Microsoft® S6 DISINFECTION AND DISINFECTANTS. lid is made to fit tightly by means of screw bolts and a rubber gasket. The lid carries the thermometer, the pressure gage, and the safety valve, and a small opening provided with a stop-cock for the purpose of expelling the air. If all the air is not expelled from the apparatus the "dead spaces" will have a much lower temperature than that registered on the thermometer ; for instance, the steam itself may register Fig. ij. 'SI!C€6i Section through Autoclave. a temperature of 130° C. while the fluids exposed may only reach 70° to 80° C. Therefore, in using this form of sterilizer it is customary to allow the steam to escape in full force for several minutes from the opening (x, Fig. 15) before permitting the pressure to rise. In the sterilization of liquids, for which this apparatus is frequently used, it is important, at the conclusion of the process, not to take off the lid or open the valve, or in any Digitized by Microsoft® PHYSICAL AGENTS. 57 other way release the pressure until the apparatus has cooled ; otherwise the condensed steam causes a diminished pres- sure, in which the superheated liquids will boil energetically, resulting in a bubbling over, a blowing out of stoppers, or bursting of the flasks. It is therefore necessary to wait until the pressure is zero, as registered on the gage ; or better, until the condensing steam produces a partial vacuum and the air is automatically sucked in through the vacuum valve, which is sometimes fitted in the lid of the apparatus for this very purpose. The steam disinfecting chamber has The Steam reached a high degree of usefulness through Chamber, the gradual perfection of the details of its working parts. These chambers are some- what complicated and their mechanical construction must be mastered in order to insure reliable results. The Klinyoun-Francis steam disinfecting chamber is most widely used in the United States, and has the advantage of being applicable to the disinfection of large quantities by a variety of methods. It may be used with streaming steam or with steam under pressure; with formaldehyd gas alone or with this gas in combination with dry heat; and finally with various combinations of these methods, with or without a vacuum. The disinfecting chamber itself may be rectangular or cylindric in shape, the former giving more effective space for the objects to be disinfected, the latter being a stronger and cheaper method of construction. The chamber is built of an inner and an outer shell, forming a steam jacket, as shown in figure i6. The steam jacket serves several pur- poses. By heating the contents of the disinfecting cylinder before the steam is turned in, it avoids condensation ; during Digitized by Microsoft® 58 DISINFECTION AND DISINFECTANTS. the process of disinfecting it helps keep the steam in the chamber "live," thereby preventing the wetting of the objects being steamed; after the disinfection is finished and the chamber opened the heat from the steam in the jacket Fig. 1 6. Cross-section through Steam Disinfecting Chamber. may be used to dry the objects which have been exposed. Therefore, in using this apparatus for disinfecting with steam, either with or without pressure, the steam is kept circulating in the jacket from the beginning to the end of the process. In disinfecting with formaldehyd gas com- Digitized by Microsoft® PHYSICAL AGENTS. 59 Digitized by Microsoft® 6o DISINFECTION AND DISINFECTANTS. bined with dry heat, the steam is kept in the jacket through- out the process, so that the gas and the air contained within the cylinder may be kept at the required temperature. In the jacket the steam has a perfectly free circulation, so that the entire disinfecting cylinder, with the exception of the doors, is surrounded by live steam. The outer shell of the jacket is protected with a covering of sectional magnesia, asbestos, or some other non-conducting substance. The steam from the boiler passes through the main steam pipe A (Fig. i8) to the pressure-reducing valve (2) and thence to the bottom of the jacket at B, B: Into the disinfecting chamber itself the steam can only be admitted from the jacket, through the circulating pipes, A, C, B (Fig. 16), and after circulating through the disin- fecting chamber in the direction as shown by the arrows, is allowed to pass out with the drip through the drain D (Fig. 17). Upon the completion of the process the steam may be blown off through the vacuum pipe F, but this outlet should not be used during the steaming, because the desired circulation would not be obtained. It will be noticed that the steam is admitted to the bottom of the jacket, but to the top of the disinfecting cham- ber, which is designed to favor the expulsion of the air through its outlet at the bottom, by means of the descending column of steam. Therefore, in order to expel all the air and fill the chamber with steam, it is essential to open the drain D (Fig. 17) while the steam is entering through B, B, and this outlet, D, should not be closed until the steam escapes freely. In using the vacuum attachment to expel the air contained in the apparatus, the modus operandi is somewhat different. A partial vacuum may be obtained in steam chambers of this type with the ejector (4, Fig. 18). The object of the Digitized by Microsoft® ^ n ri Si- ao 5 ■^ o e Q D-i B " « g fa m 01 V rt «ajflii>E**j fart •§£|s°'^.2tes l=?-E^Kgo- ^^^1^ a u « — « u a.0';: _ c S S . m t^ rti ~ T> ^ WI _ W m S u o u 2 ?as&??MSc«^^ - |££-a«S. Its §•5 2 S^ ii^ E>2 ^ S "u ■ Si P '->-2 t- ^ -O o )H M w ih c (U a* "JJi =25 rt7, . § = -2 •-:*jiH rt S rtfl] fa_'J3 ^ rt aaS >■ K rtfi^ o 6i Digitized by Microsoft® 62 DISINFECTION AND DISINFECTANTS. vacuum is to facilitate the penetration of the steam, which rushes into all the interstices of fabrics and inaccessible places, to take the place of the air which has been with- drawn. The ejector works upon the familiar principle of the water vacuum pump, the air being drawn or sucked along with the current. With a pressure of 80 pounds in the boUer and the valve J (Fig. 18) wide open, the ejector will produce a vacuum of 15 inches in one of the largest sized chambers in one minute, which is very much quicker than can be accomplished with the ordinary forms of piston pumps. The formaldehyd attachment consists of a copper retort (10, Fig. 18), in which the formalin mixed with calcium chlorid is heated by means of a copper steam coil. This attachment does not differ in principle from the method of evolving formaldehyd gas from its watery solution mixed with a neutral salt under pressure, and any of the forms of apparatus described in the following pages (Chapter II) will answer as well as the particular retort furnished with the steam chamber, if not better. The formaldehyd re- tort is filled through the funnel, P, with the mixture consist- ing of formalin (40 per cent.), to which is added 20 per cent, of calcium chlorid and sometimes 10 per cent, of glycerin. About 10 ounces of this mixture are used for each 1000 cubic feet of air space. The steam is turned on through the valve M to the coil in the retort, and the drip from this coU passes out through the valve N. A pressure of at least 45 pounds to the square inch in the retort, as shown by the gage B, must be obtained before the gas is allowed to pass through the valve T into the disinfecting chamber. Care must be exercised at the beginning of the operation to be sure to allow the air to escape from the retort through the valve T, so that the gage will register the pressure of the gas and not the pressure of the retained air. Digitized by Microsoft® Digitized by Microsoft® Digitized by Microsoft® Digitized by MicroMft® Digitized by Microsoft® Digitized by Microsoft® Digitized by Microsoft® PHYSICAL AGENTS. 69 To the right of the copper formaldehyd retort is a com- plete duplicate in iron (ii, Fig. i8), for the evolution of ammonia, which was formerly used to neutralize the for- maldehyd at the completion of the process, but which is seldom used now because it is simpler to allow the gas to blow away by opening both doors of the disinfecting chamber. The chambers are open at both ends so that the infected objects may be introduced from one side, and taken out upon the other, which diminishes the risk of reinfecting them. The chambers are closed by means of large cast-iron doors, which swing upon cranes. Formerly the doors were locked into place by means of eyes and screw bolts, but as this method is time-consuming, the doors are now provided with a series of radial bolts which are driven home by simply turning a wheel at the center. The joint between the door and the chamber is made tight by means of a heavy rubber gasket. The door should not be pressed against this gasket more firmly than is found necessary to retain the steam, otherwise the rubber will soon be rendered useless. In using the vacuum, the air pressure effectually keeps the door closed, so that it is only necessary to have it closed firmly enough at the beginning of the process to make a tight joint in order to start the vacuum. In addition to the above-mentioned attachments, the disinfecting chambers are also supplied with a thermometer (7, Fig. 18), the stem of which is turned at right angles and protrudes through the steam jacket, so that the instrument is supposed to register the temperature of the interior of the disinfecting chamber. The thermometer, however, is so close to the jacket that it is influenced by the heat in the jacket, which is usually higher than the tem- perature of the interior of the chamber. The thermometer should be in the door, or differently arranged, to give trust- 5 Digitized by Microsoft® 7° DISINFECTION AND DISINFECTANTS. worthy results. In disinfecting with. steam under pressure, the pressure, as indicated by the gage, is a more reliable guide than the temperature registered by the thermometer. There are forms of mercurial and metallic thermometers Fig. 22. Electric Thermometer. that make an electric contact when a certain temperature is reached, and which may be connected to ring a bell. They have the decided advantage in that they may be placed any- where within the chamber, even in the center of bundles, etc., and are more trustworthy than any form of mercurial Digitized by Microsoft® PHYSICAL AGENTS. 71 instrument fastened through the heavy metalHc walls of the apparatus. An ingenious form of thermometer, made to register when the temperature reaches 100° C, has been designed by Merk and is shown in the accompanying illustration (Fig- 23). A small stick of the metallic substance which is supplied with the instrument and which melts at exactly 100° C, fastened at A, keeps the electrodes at B and C apart. The Automatic Thermometer. entire thermometer D is then placed in the box B for pro- tection, and this is placed in the chamber, or in the inside of bundles to be disinfected. The insulated wires from F and G are connected with a battery and bell. As soon as the temperature reaches 100° C. the little metal stick melts, the contact is made between B and C, and the bell rings. This form of thermometer is more accurate than the pyrom- eters which depend upon the contact being made by the unequal expansion of a compound metal bar, for the reason that moisture collects upon the electrodes and an electric Digitized by Microsoft® 72 DISINFECTION AND DISINFECTANTS. contact is sometimes made before the metal parts actually touch, thereby giving false readings. The chamber is also provided with a galvanized iron or Fig. 24. Pyrometer. copper hood, to prevent rust-stained drip from soiling the clothing and other objects exposed to the steam; gages to Fig. 25. Scheme for Installing Electric Thermometer in the Steam Dis- infecting Chamber. indicate both vacuum and steam pressure (6 and 13, Fig. 18) ; and a safety valve (5, Fig. 18) to prevent overpressure in the Digitized by Microsoft® - a r^ ^ VJ \ -C ''X %^ /^ ^N --^ I ^77 6 ^^^! 1 ^ ASH PIT li I DOUBI.& eUUPHUR. IFURNACE Longitudinal Section through Sulphur Furnace. live coals, or by a red-hot spike. When once lighted, there is no trouble in keeping the sulphur burning. The air enters at A (Fig. 45) through a valve arranged to regulate the amount of flow. It then passes over the burn- ing sulphur in the direction shown by the course of the arrows to the fan. The fumes are compelled to take a devious course around the baffle-plates and angle irons, as shown in the drawing, in order to insure the complete combustion Digitized by Microsoft® 130 DISINFECTION AND DISINFECTANTS. of the oxygen of the air. The angle irons also act as spark- arresters. From B the fumes are sucked to the fan, which is actuated by a steam-engine or electric motor, and which forces the gas through the pipes to the space to be disin- fected. In using the furnace, care must be taken not to run the fan at too high a speed, in which case the oxygen of the air will not all be converted into sulphur dioxid, and further- more the strong current will carry over a quantity of uncon- sumed sulphur in a state of fine division. Running the fan at too high a speed also causes overheating of the pipes, or the carrying over of sparks of burning sulphur, thereby rendering possible accidents from fire. The pipe conducting the fumes from the sulphur furnace to the compartment to be disinfected gives a great deal of trouble. It is apt to become clogged with the sulphur which sublimes in the cooler portions, and unless special care is taken the heat generated is sufficient to burn out and de- stroy the materials of which the pipe is constructed. Ordin- arily this pipe must be 6 to 8 inches in diameter. Rubber hose of this size is not only very costly and heavy, but the sulphur soon vulcanizes the rubber, rendering it brittle and useless. A good pipe for this purpose may be made of light galvanized iron sections 2 or 3 feet long, joined with copper wire to take the strain, and the joint made tight with several layers of canvas, saturated and coated with some fire-proof paint.* No arrangement is made in this form of apparatus for adding watery vapor to the sulphur fumes, which is neces- sary to obtain the maximum disinfecting power of the gas. * See the article on this subject in the Annual Report of the Marine Hospital Service for 1897, page 269, by the author. Digitized by Microsoft® Fk;. 46. e 9 o l)(.li;l,l'; SlLTHLiR FUKN'ACIi. Digitized by Microsoft® Digitized by Microsoft® Digitized by Microsoft® Digitized by Microsoft® Digitized by Microsoft® Digitized by Microsoft® GASEOUS DISINFECTANTS. 1 37 It is therefore necessary, in dry weather, to add a sufficient quantity of vapor, preferably by means of a steam jet. The air should be saturated. The holds of wooden vessels, in which sulphur fumigation is such a useful disinfecting pro- cess, are usually so damp that the addition of more moisture is not necessary. The portable sulphur furnace depicted in the accompanying illustration is a very useful apparatus in municipal work, particularly for the treatment of sewers, warehouses, stables, barns, grain elevators, and similar large rough structures which are infested with vermin. This form of furnace was used with success in the fight against the rats in the sewers of San Francisco, on account of the plague. It simply con- sists of the sulphur furnace described above, placed upon a truck, so that it can readily be hauled from place to place. With this apparatus the sulphur dioxid can be forced into out-of-the-way places inaccessible to the pot method. The truck is supplied with a small vertical boiler and steam- engine to actuate the fan. Hydrocyanic acid (HCN) is used exten- Hydrocyanic sively in the disinfection of nursery, stock Acid. and greenhouses, as well as in flouring-mills against weevils, in railroad cars against bed- bugs, and in tobacco warehouses against insects in general. This gas is a fatal poison for all the forms of animal life. It is much less destructive to vegetable life. In other words, it is a very powerful insecticide, but a weak germicide. Against organisms no hardier than those of diphtheria and typhoid, it appears, according to Fulton,* to be effective. *J. S. Fulton, "American Medicine," May 11, 1901, p. 256. 10 Digitized by Microsoft® 138 DISINFECTION AND DISINFECTANTS. lyike the other gaseous disinfectants, this substance pos- sesses no marked power of penetration. The extremely poisonous nature of hydrocyanic acid gas makes it necessary to exercise very great care in its em- ployment. In fact, the great danger attending its use for- bids its employment about the household. In practical disinfection it may occasionally find a place in the treatment of stables, granaries, outhouses, the holds of ships, and similar uninhabited places, particularly if infested with vermin. Hydrocyanic gas is lighter than air and has an agreeable, aromatic odor, quite familiar in the flavoring essence of bitter almonds. It is best generated by the action of dilute sul- phuric acid upon potassium cyanid, in the following pro- portions : Potassium cyanid I.o Sulphuric acid, I.S Water, 2.25 The first step is to dilute the acid, which is best done by adding the acid to the water, in a vitrified clay jar or re- ceptacle capable of withstanding the heat. The whole amount of the cyanid must be put into the acid at once, and as the evolution of the gas is very rapid, the operator must be ready to leave the spot immediately. As pointed out by Fulton, it is convenient to tie the cyanid up in a bag, which is lowered into the acid by a cord passing outside of the room. The amount of gas used for plant fumigation, expressed in terms of cyanid, is about i ounce, or 25 grams per loo cubic feet. For room disinfection a greater amount is necessary. This gas has few advantages over sulphur dioxid in ridding a place of vermin, and its germicidal value is inferior to formaldehyd; and as its poisonous nature is such a serious drawback, it has a very limited place in practical disinfection. Digitized by Microsoft® Fig. 4q. r-"T? Portable Sulphur Furnace. Digitized by Microsoft® Digitized by Microsoft® GASEOUS DISINFECTANTS. I4I Chlorin is a germicide of considerable, but Chlorin. uncertain, power. It has little practical usefulness owing to its poisonous and de- structive action. Both in its free gaseous state and in its watery solution it has very powerful deodorizing proper- ties. In the free state moisture is necessary for its action. At best this gas is but a surface disinfectant. Chlorin (CI) is an extremely irritating gas, and great care must be observed in its employment, for the inhalation of very weak proportions of the gas produces serious irritation, resulting in spasm of the larynx, bronchitis, and even in death. Chlorin (sp. gr. 2.47) is heavier than air, and tends to fall; therefore the vessel generating the gas should be placed in an elevated position, in order to obtain anything like effective diffusion. Carpets, curtains, and fabrics gener- ally are injured by its action, and the element is a very active bleaching agent for all the organic pigments. The germicidal action of chlorin depends upon its great affinity for hydrogen. So strong is this affinity that it com- bines with the hydrogen of water in the presence of light, liberating the oxygen in its nascent state, thereby enabling it to exert its power against organic matter. Its value as a deodorant depends upon its power of decomposing the offensive gases of decomposition, such as sulphureted hydro- gen and the volatile ammoniacal compounds. In practice the most convenient method of generating the gas is by decomposing i J pounds of chlorid of lime with 6 ounces of strong sulphuric acid. This produces sufficient gas for the disinfection of 1000 cubic feet of air space. Or, the gas may be generated from — Common salt, 8 ounces. Magnesium dioxid, 2 " Sulphuric acid, 2 " Water, 2 " Digitized by Microsoft® 142 DISINFECTION AND DISINFECTANTS. Mix the water and the acid together and then pour the mixture over the salt and magnesium dioxid, in a glazed earthenware basin. The basin should rest on sand. Another method of generating chlorin gas is by adding 4 parts of strong hydrochloric acid to i part of magnesium dioxid. According to Fisher and Proskauer,* in ordinary dry air 5.38 parts of free chlorin per 1000 cubic feet of air space appears to be necessary to kill micro-organisms. If the air be moistened, which may be done by wetting the walls, floors, etc., or by diffusing steam, only 0.3 per cent, by vol- ume in each 1000 cubic feet of air is sufficient, disinfection being completed in five to eight hours. According to these same authors, chlorin gas is a highly unsatisfactory disin- fecting agent from a practical standpoint, on account of the impossibility of regulating all the necessary conditions, and the uncertainty of achieving the object to be attained. Stern- berg! found that an exposure of six hours to a constant strength of one-half of one per cent, of chlorin was necessary to destroy the potency of vaccine virus. For the purposes of practical disinfection, Munson very properly states that free chlorin is much inferior to sulphur dioxid, since it is more difficult to control, more dangerous to manipulate, and more destructive in its effects. The disinfecting power of oxygen depends Oxygen. largely upon the physical state in which it exists. For instance, the oxygen in the air has feeble, if any, germicidal properties, while nascent oxy- gen and ozone are powerful germicides. The germicidal action of oxygen depends upon its very * " Mittheilung aus dem kaiserl. Gesundheitsamt," II, p. 228. t " Military Hygiene," Munson, p. 786. Digitized by Microsoft® GASEOUS DISINFECTANTS. 1 43 active property of combining chemically with the albuminous matter of the cell protoplasm. The oxidizing properties of this element, acting upon organic matter, and converting a great part of it into carbon dioxid and water, explains the purifying power of fresh air. Most bacteria, to grow and multiply, require the presence of oxygen. They are called aerobic. There is a large class of organisms that will not develop in the presence of minute traces of free oxygen. These are called anaerobic. In fact, the oxygen of the air acts like a poison or strong antiseptic for this class of vegetable life, among which are tetanus, symptomatic anthrax, malignant edema, etc. On the other hand, oxygen has no appreciable effect upon the spores of these bacteria. Pasteur * showed that the cocco-bacillus of cholera attenu- ates in the presence of the air. He proved that it is the oxygen that causes this phenomenon, by preserving the virulence of a culture when hermetically sealed. According to the researches of P. Bert and Reynard, f oxygenated water has the power of arresting fermentation and putrefaction. Solutions containing lo or 12 volumes of oxygen have, according to IvUcas-Champonniere,t a very notable antiseptic power. Ozone is the allotropic form of oxygen. Ozone. containing three atoms of that element to the molecule instead of two. In sufficient concentration it is a powerful germicide, and has lately * " Du I'attenuation du virus du charbon des poules," Pasteur. f " Influence de I'eau oxygenic sur la fermentation," "C. R. de I'Acad. des Sci.," May 22, 1882, and " Gaz. Med.," 1880. J ' ' Sur la valeur antiseptique de I'eau oxygen^e," ' ' Acad, de Med. ," Dec. 6, 1898. Digitized by Microsoft® 144 DISINFECl'ION AND DISINFECTANTS. found practical use in the sterilization of water on a large scale, for the use of cities and towns. There is not sufficient ozone in the air normally to exert any appreciable oxidizing or disinfecting properties. Ozone is formed by a number of chemical reactions, but in actual practice it is produced by the discharge of elec- tricity in the oxygen of the air. It is a gas with more power- ful oxidizing properties than free oxygen. It bleaches in- digo and liberates iodin from potassium iodid, which is one of the tests for its presence. Ozone has a peculiar odor familiar about electric dynamos. It has never been obtained free from oxygen, and is regarded simply as a modification of that element, the formula being expressed as Ofi, in- dicating that three volumes of the gas have been condensed into two. Ozone is nearly insoluble in water. It is owing to this property that special apparatus is necessary in order to use it for the disinfection of water. In the patented processes the ozone is generated by electric discharges in special ap- paratus called ozonizers, which produce this substance in proper concentration. The gas is then brought in contact with the water in large columns containing a porous stone. The water trickles down through the porous substance while the ozone enters the column from below, so that there is intimate contact between the water and the gas. The water is sterilized almost instantly, and as the ozone also oxidizes the organic matter and leaves no undesirable chemical resi- due, the method has very much to recommend it for the central purification of the water-supply of large cities. The method is much too expensive and cumbersome for the dis- infection of water on a small scale. Digitized by Microsoft® CHAPTER III. CHEMICAL SOLUTIONS. General Considerations — Bichlorid of Mercury — Carbolic Acid — The Cresols — Formalin — Potassiuin Permanganate — Lime — Chlorinated Lime — The Hypochlorites — Ferrous Sulphate — Zinc Chlorid — Soaps. A chemical solution, to be of practical Gene;rai, Con- value, must not only be strongly germicidal SIDERATIONS. as shown by laboratory experiments, but must also meet the many exacting require- ments of general practice. Such substances are few in number. Almost any chemical substance, under one condition or another, has the power to retard the development or destroy the activity of microbial life. We need only mention the well-known power of common salt or of sugar, which in sufficient concentration prevents the processes of fermenta- tion and decomposition. In weaker dilutions these same substances, on the contrary, favor the growth and multi- plication of almost all the known bacteria. The undeserved reputation of many so-called chemical disinfectants depends more upon their vile odor or judicious advertising than upon actual efficiency. Only such sub- stances will be enumerated below as by scientific tests and actual experience have proved to be trustworthy. There is a great difference between the strength of solu- tions required to prevent fermentation and putrefaction, I4S Digitized by Microsoft® 146 DISINFECTION AND DISINFECTANTS. and the strength required to destroy the causes of these processes. The first are antiseptics, the second are disin- fectants, or germicides. For instance, corrosive sublimate solution of the strength of i : 15,000 will prevent the growth and development of all bacteria. Even as weak a solution as I : 300,000 will prevent the growth and development of some bacteria; whereas it takes a solution of i : 1000 to de- stroy them in a short time. Formalin (40 per cent, formal- dehyd) will prevent the development of many bacteria in a solution of I : 50,000, while it requires a i per cent, solution to kill the germs and their spores. It is not enough, in applying any agent whose best working strength is known, to use a small volume of the solution of that particular strength. The substance itself must be used in such an amount that it shall be present throughout the whole mass in the proportion required. Thus, an agent that is effective in a 2 per cent, solution cannot be used in that strength to disinfect an equal volume of infected mate- rial, since the mixture would then contain but i per cent. Time is an essential factor too frequently disregarded in disinfecting with chemical solutions. Very few chemical dis- infectants act instantly, even in strong solutions and under favorable circumstances. The micro-organisms are so often in clusters, or are surrounded by mucoid films, or embedded in nitrogenous materials, that no inconsiderable time is required for the disinfecting solution to penetrate to the^erm. If the microbes are dry, it takes a certain time to wet them before the chemical in solution can act. All these and other factors must be added to the time actually necessary for the chemical in solution to destroy the life of the germ after it comes in direct contact with the protoplasm of the cell. It therefore will not suffice to dip objects to be disinfected into cold solution, momentarily, as is so often done. If the Digitized by Microsoft® CHEMICAL SOLUTIONS. 1 47 objects are mechanically clean they may be immersed until thoroughly wetted by the solution, and then hung up so that the disinfecting solution may dry, preferably in the sun. Otherwise they should be kept completely immersed a sufficient length of time, depending on the strength of solution, as stated under each chemical. Weak solutions, of course, take a longer time to act than strong solutions. The temperature so greatly influences their disinfecting power that it is strongly recommended always to use warm solutions in actual practice. Even slight changes of tem- perature make a great difference. Feeble antiseptic solu- tions become strong germicides when heated. A good in- stance of the effect of temperature is given by Heiden,* who found that anthrax spores which survived the effects of a 5 per cent, carbolic acid solution for thirty-six days at room temperature were destroyed in half an hour in the same solution at 55° C. At 75° C. it took only three minutes to kill them ; a 3 per cent, carbolic acid solution killed the same spores at this temperature in fifteen minutes, and a i per cent, solution in from two to two and a half hours. The medium in which the germs exist also makes a great difference so far as the power of a germicidal solution is con- cerned. Behring found, for example, that anthrax bacilli in water are killed in a few minutes with a sublimate solution of the strength of i : 500,000. In bouillon it required a strength of i : 40,000; while in blood-serum, if the disinfec- tion is to be accomplished in a few minutes, a strength of I : 2000 is not always sufficient. Therefore, in the presence of organic matter or filth, stronger solutions and longer exposures are required. The choice of the chemical selected depends somewhat *"Centralbl. filr Bakt.," Bd. IX, 1891, p. 221 ; and " Archiv fiir Hy- giene," Bd. XV, 1892. Digitized by Microsoft® 148 DISINFECTION AND DISINFECTANTS. Upon the nature of the substance to be disinfected. For example, bichlorid of mercury is totally inapplicable to tlie disinfection of albuminous matter. Certain chemicals, too, have a particular power to destroy certain organisms, while they are relatively inert toward others. Taken altogether, therefore, the choice of the chemical, its strength and time of apphcation, the temperature of the solution and its method of employment, are all problems which must be solved for each particular case. Chemical substances act in a great variety of ways to bring about the destruction of bacteria. It is impossible, as Munson states, to explain in many cases the manner in which disinfection is accomplished by chemical agents, any more than to say that the microbes are poisoned by the disinfectant. In particular instances this is accomplished by a union between the disinfectant and the protoplasm of the bacteria, as appears to be the case with corrosive sub- limate or formalin. In some instances the mycoprotein of the cell is coagulated, as in the case of carbolic acid and homologous substances. According to the newer chemical theories, there are found in watery solutions certain substances in the condition of electric dissociation. These substances are divided into electro-positive (-f) and electro-negative ( — ) components — that is, ' 'ions." The higher the grade of this dissociation, the greater is the disinfecting power of the solution. In the case of the soluble metallic salts, and especially mercury, it depends upon whether in the electrolytic dissociation the metal exists as an independent ion, or whether it exists as a complex ion. In the first case the solution has strong disinfecting properties, in the second these properties are much weaker. In other liquids, as for example alcohol, ether, etc., the metallic salts have very slight dissociation. Digitized by Microsoft® CHEMICAL SOLUTIONS. I49 which according to Kronig and Paul explains the weaker disinfecting power of these solutions. The disinfecting power of metallic salts depends, furthermore, not only upon the specific influence of the metal ion, but also upon the other ions, and upon the unassociated parts of the metallic salts. The reaction of the solution and of the medium to be disinfected varies with the substance employed. Thus, lime is an alkali, and if used to disinfect an acid substance, enough must first be added to neutralize the medium, and then an additional amount of the lime must be added neces- sary to accomplish the disinfection. In the same way, if mercuric chlorid is added to solutions containing sulphids, caustic alkalies, or certain metallic salts, sufficient must be added in order to first precipitate these substances and then enough more added to exert its disinfecting action. Like- wise, the greater the number of germs to be destroyed, the greater the amount of disinfectant required to accomplish the purpose. There are various ways of applying chemi- Methods of ^^^ solutions for disinfecting purposes. No Using method is trustworthy that does not thor- ChEmical oughly wet the object with the solution so Solutions, that there may be direct contact between the substance in solution and the contagious principle against which the process is directed. As a rule this may best be accomplished by immersing the infected object in the solution. When this is not practicable, the solution must be applied to the object. A favorite way of applying disinfecting solutions to surfaces, such as walls, ceilings, the holds of ships, and other rough structures, is by means of a hose. The pressure is supplied either by elevating the tank containing the solution or by means of a pressure Digitized by Microsoft® 15° DISINFECTION AND DISINFECTANTS. pump. As bichlorid of mercury is practically the only dis- infectant used in this way, the pump should be made of iron and have no copper, brass, or steel parts exposed to the cor- roding action of the solution. In applying the disinfecting solution to the surfaces of a room or the hold of a ship the operator should begin at one corner of the ceiling, wetting that first, and then go over Fig. 50. Apparatus for Spraying Disinfecting Solutions in a Nebulous Spray. every portion of the walls systematically, from above down- ward. The floor conies last. Solutions thus applied remain but a short time in contact with the surfaces to be disinfected. It is therefore an ad- vantage to have the solution hot and strong, and to have sufficient pressure in order to obtain the mechanical effect produced by a vigorous stream. Digitized by Microsoft® CHEMICAL SOLUTIONS. 151 A good way of applying disinfecting solutions to surfaces is by means of mops, brooms, and the like, for we add the mechanical action to the power of the germicide. The pulverizer is very popular in France for the disinfec- tion of walls and other surfaces with solutions of bichlorid of mercury. The apparatus for this purpose consists of a Fig. 51. metal cylinder fitted with a simple force pump which com- presses the air in the reservoir. The solution does not come in contact with the pump. The current of air driven through the one tube sucks the solution through the other, and sprays it from the nozle in a nebulous cloud, similar in principle to the well-known hand atomizers. It is easy to demonstrate, by using a colored solution upon a white wall or sheet, that a liquid sprayed in this way does not wet the entire surface. The method is therefore an un- scientific and unreliable one when used with a non-volatile chemical. Digitized by Microsoft® 152 DISINFECTION AND DISINFECTANTS. The pulverizer, as used by the disinfecting corps in Paris for the treatment of walls and other surfaces with a fine spray of bichlorid of mercury solution, is shown in the accompanying illustrations. Fig. 52. The suits of the operator are made of canvas and are taken off in the room at the completion of the process, and placed in the bag with the other articles for steam disinfection. Bichlorid of mercury or mercuric chlorid, BiCHivORiD OF commonly called corrosive sublimate, is one Mercury, of our most valuable and potent germicides. It destroys all forms of microbial Hfe in Digitized by Microsoft® CHEMICAL SOLUTIONS. 153 relatively weak solutions. It kills both the germs and their spores, and therefore can be used as a disinfectant against all the known forms of infection. It is not a deodorant. The disadvantages of bichlorid of mercury are that it cor- rodes metals, forms insoluble and inert compounds with albuminous matter, and is very poisonous. These disad- vantages place distinct limitations upon its use. Mercuric chlorid (HgClj) is a white, crystalline mass, of heavy specific gravity — 5.43. It volatilizes somewhat more readily than mercurous chlorid (calomel) even at room tem- perature. On account of this property caution must be observed in using bichlorid solutions about living rooms, some instances of poisoning having been traced to this use. It is therefore well to follow the bichlorid with clear water, and a mechanical cleansing is always in order. Bichlorid of mercury wUl dissolve in 16 parts of cold water and 3 p^rts of boiling water. As it is soluble with much dif- ficulty in water, it is convenient to keep a saturated alco- holic solution on hand, and use this to make the watery solutions. A 25 per cent, solution may readily be made in alcohol, and by the addition of hydrochloric acid or am- monium chlorid will keep indefinitely. This would be rather expensive for making up the large quantities required in flushing the holds of ships or other extensive surfaces. The solution may be facilitated by a little device pointed out by Geddings. The correct quantity of the bichlorid is weighed out and placed in a canvas bag which is hung over the faucet so that the water will run through it into the tank or receptacle holding the solution. If this method is not convenient, the bichlorid must be pounded to a powder and care must be exercised that it is all dissolved before using. The solution of bichlorid is facilitated by the presence of hydrochloric acid, or a chlorid, such as ammonium chlorid Digitized by Microsoft® 154 DISINFECTION AND DISINFECTANTS. or common salt. Twice the quantity of these substances to the quantity of bichlorid used is added. If the solution is to be pumped or otherwise come in contact with metals, it is better to use the chlorids than the acid, because the acid solution of bichlorid is very destructive to the metal parts of the pump, and to the couplings and nozle of the hose, particularly if made of copper or brass. Sea-water contains about 4 per cent, of salt, and is well suited for making bichlorid solutions. It is extensively used at the seaport quarantine stations for this purpose. La Place first pointed out that the addition of a small amount of an acid to the solution of bichlorid of mercury greatly increases its efficiency, and by lessening the formation of insoluble albuminates also increases its power of penetra- tion. This has latterly been denied by Kronig and Paul,* who assert that the addition of sodium chlorid to watery solu- tions of bichlorid diminishes its power. They found that potassium chlorid or hydrochloric acid has the same effect. The germicidal action of bichlorid solutions seems to de- pend upon the reaction that takes place between the bi- chlorid in solution and the mycoprotein of the germ. This reaction is a chemical one, and of course requires direct contact between the albuminous matter of the germ and the bichlorid of mercury in solution, as well as a certain time and concentration to effectually destroy the life and viru- lence of the cell. Geppert f has shown that in the reaction that takes place between bichlorid of mercury and the spores of anthrax, the vitality of the latter may seem to be lost, but that the bichlorid may be precipitated from its com- * " Zeitschr. f. physik. Chem.," Bd. XXI, 1896, p. 449 ; and " Zeitschr. f. Hygiene," Bd. XXV, 1897, p. 65. t " Bed. klin. Wochensdir.," 1889, No. 36; and " Deutsch. med. Wochenschr.," 1891, No. 37. Digitized by Microsoft® CHEMICAL SOLUTIONS. 1 55 bination by the action of ammonium sulphid, which re- stores the vitality of the spore. Like a great number of chemical reactions, the combina- tion of the bichlorid solution with the germ protoplasm is very much hastened by the aid of heat. The action of the moist heat itself plus the effect of the bichlorid makes hot solutions of this chemical a very powerful germicidal agent. Bichlorid of mercury is decomposed by lead, tin, copper, and other metals. It therefore should not be made or kept in metal receptacles. Ivcad pipes are rendered brittle and worthless by passing this solution through them. Care must therefore be exercised in using this substance about water-closets and plumbing. On account of the property that this substance has of uniting with albuminous matter to form insoluble and inert compounds, it cannot be used for the disinfection of media containing much organic matter. It is totally inapplicable to the disinfection of sputum, excreta, and the like, for it forms a coagulum which prevents the further penetration of the bichlorid. It also unites chemically with the sulphids and the caustic alkalies, so that it should not be employed as a disinfectant when these substances are present in any considerable amount. If it is used, enough of the bichlorid must first be added to precipitate these chemical substances and then a sufficient additional quantity so that the bichlorid of mercury wUl be present in the desired proportion. To diminish the danger from accidents bichlorid solutions in households and hospitals should be colored with perman- ganate of potash, or indigo, or one of the anilin dyes. The germicidal power of bichlorid of mercury has been very carefully studied in many laboratories, so that we are in possession of definite knowledge as to the exact strength and time necessary to accomplish disinfection. II Digitized by Microsoft® 156 DISINFECTION AND DISINFECTANTS. A solution of i : 1000 is ample for the destruction of all the non-spore-bearing bacteria at the ordinary temperatures, provided the exposure is continued not less than half an hour. Many bacterial cells are killed at once when brought in direct contact with a solution of this strength, and the great majority are destroyed within fifteen minutes ; but the extra time as given allows for penetration, which is usually required in actual practice. Solutions of bichlorid of mercury of the strengths of i : 800 and I : 500 are very strong germicides and will kill non- spore-bearing infections in a short time. For spores a solution of 1 : 500 is necessary and an expo- sure of one hour. Articles may be disinfected by immersing them in a solu- tion of I : 2000, provided that the exposure is not less than two hours. A strength of i : 1 5,000 is sufficient to prevent putrefaction and fermentation. Carbolic acid makes a very useful disin- CarboIvIC fecting solution with a wide range of appli- AciD. cation. It should not be depended upon to kill spores. As it does not coagulate albu- minous matter as actively as corrosive sublimate, it may be used for the disinfection of soiled clothing and bedding, as well as for excreta and the like. However, it is not so trustworthy for these purposes as some of its homologues, such as tricresol or lysol. Carbolic acid is also known as phenic acid, phenol, phenyl alcohol, and coal-tar creasote, and is represented by the chemical formula CeHeO = CeHjOH. It is produced in the dry distillation of coal and is the chief constituent of the acid portion of coal-tar oil. Pure phenol crystallizes in Digitized by Microsoft® CHEMICAL SOLUTIONS. I 57 long, colorless needles. The commercial product forms a crystalline mass, which is apt to turn reddish in time, and in contact with moist air deliquesces to a brown liquid. Car- bolic acid has a penetrating odor, a strong burning taste, and is a corrosive poison. The carbolic acid of commerce contains impurities, such as the cresols and higher homologues, some of which have a higher germicidal value than pure carbolic acid itself. The commercial product also contains tar oils which are totally lacking in bactericidal properties. The cruder chemical containing these impurities has been shown to be superior to the highest grades of the refined acid, which is practically pure phenol. At ordinary temperatures carbolic acid is soluble in about 15 parts of cold water — that is, a saturated solution contains between 6 and 7 per cent. It is commonly used in solutions of 3 to 5 per cent., which are entirely trustworthy for the destruction of all infectious processes due to non-spore- bearing organisms. The acid dissolves in water with some difficulty; care should therefore be exercised to mix it thoroughly by agita- tion, preferably in warm water. It is not destructive to fabrics, colors, metals, or wood, in the strengths used, and therefore may be employed for the disinfection of a great variety of objects. The fact already mentioned that it does not actively coagulate albu- minous matters renders it suitable to the disinfection of urine, excreta, soiled linen, and the like. There has been much disparagement of carbolic acid lately because laboratory tests have clearly demonstrated that it cannot be depended upon to kill spores. This limits, but does not destroy its usefulness, for fortunately the great majority of the epidemic diseases of man are due to non- Digitized by Microsoft® 158 DISINFECTION AND DISINFECTANTS. Spore-bearing bacteria. Carbolic acid should not be used to destroy the infection of tetanus, anthrax, malignant edema, and other diseases due to spore-bearing bacteria. A I per cent, carbolic acid solution or even a 2 per cent, solution has no certain effect upon anthrax spores. A 3 per cent, solution requires seven days, a 4 per cent, solution three days, and a 5 per cent, solution two days to kill anthrax spores. These figures do not apply to all varieties of anthrax spores, for there are some, as v. Esmarch * found, that can withstand forty days' immersion in a 5 per cent, watery solution of the acid. Teuscher f reports a resisting variety of anthrax spore that was not killed after four and a half days' immersion in pure crystallized phenol, kept liquid in the incubator. Very much weaker solutions are effective for non-spore- bearing bacteria. For instance, the germs of cholera, plague, typhoid, diphtheria and erysipelas are killed, ac- cording to Behring, by one hour's immersion in a ^ per cent, solution, while a solution of i to i^ per cent, will destroy these non-spore-bearing micro-organisms in one minute. In general practice carbolic acid is used in from 3 to 5 per cent, solutions, and an exposure of no less than half an hour. Clothing and fabrics require deep penetration, and are usually left in the solution one hour. Tricresol is about three times as powerful The CrEsoIvS. a disinfectant, bulk for bulk, as carbolic acid. A I per cent, solution is effective for all ordinary purposes. The presence of albuminous matter. in fluids to be disinfected does not interfere to any serious ex- tent with its prompt and certain germicidal action. Tri- *"Zeitschr. f. Hygiene," Bd. v, 1888. f'Zeitschr. f. Hygiene," Bd. IX, 1890, p. 510. Digitized by Microsoft® CHEMICAL SOLUTIONS. 1 59 cresol has another advantage over carbolic acid in that it may be depended upon to kill spores. Tricresol consists of a mixture of ortho-, meta-, and para- cresol. Metacresol is a liquid, the other two are solid crys- talline bodies, having a low melting-point. These cresols are some of the impurities found in commercial carbolic acid. The cresol group forms the next higher homologue to phenol, one atom of hydrogen being replaced in the latter by the methyl radical, CH3. The cresols are not very soluble in water, but solution may be brought about by the soaps or by cresol salts. The cresols accompany phenol in coal tar, from which they are obtained. Tricresol is a clear or pinkish-colored syrupy liquid. About a 2^ per cent, solution can be made of it in water. It is somewhat less poisonous than carbolic acid. Its uses are the same. It is commonly employed in a I per cent, solution. There are a number of other well-known preparations of the cresols now extensively used in surgical and hospital practice. The following from Harrington are given as trust- worthy disinfectants : Creolin contains 10 per cent, of cresols and a small amount of phenol held in solution by soap. It is a dark brown, thick, alkaline liquid, and forms a turbid, whitish emulsion with water. It is at least equal, and perhaps superior, to phenol. Lysol contains about 50 per cent, of cresols, with neutral potash soap. It is a brown, oily liquid and mixes with water in all proportions, forming a soapy, frothy liquid. It is more powerful than phenol and ranks with tricresol as a germicide. Saprol: This liquid contains 20 per cent, of mineral oil and 80 per cent, of crude carbolic acid. It is lighter than Digitized by Microsoft® l6o DISINFECTION AND DISINFECTANTS. water, and when thrown into it diffuses over the surface in a thin layer, which gradually yields its active ingredients to the strata below, so that in the course of a day the water becomes impregnated to the extent of 0.34 per cent. It is superior as a general disinfectant and deodorant to carbolic acid. Soheol is a concentrated aqueous solution of the cresols with sodium cresotinate. It contains over 2J per cent, of , cresols. It is unirritating and much less toxic than carbolic acid. As a disinfectant it is the equal, if not the superior, of any of the cresol preparations. Solutol is a solution of about 60 per cent, of cresols in sodium cresol. Those who have tested this preparation claim for it superior germicidal powers to creolin, lysol, solved, and phenol. Formalin is a very valuable disinfectant. Formalin with a wide range of usefulness in general Solutions, practice. This liquid is superior to bichlorid of mercury for many purposes, especially as its action is not retarded by the presence of albuminous matter. Formalin does not injure most articles, and it is not poisonous. It is a true deodorant. Formalin, also known as formol and under various other trade names, consists of a 40 per cent, solution of the sub- stance formaldehyd (CHOH) dissolved in water. Formal- dehyd is a gas at ordinary temperatures, and it must be condensed in order to obtain it in concentrated solution. Formalin, therefore, consists of a solution of one of the poly- meric forms of formaldehyd, especially paraformaldehyd. See page 87. The liquid is a clear solution, giving off an appreciable odor of formaldehyd gas. It is exceedingly irritating, but Digitized by Microsoft® CHEMICAL SOLUTIONS. l6l not toxic. Formalin solutions are rather unstable. There is a constant loss by evaporation if the liquid is not kept well corked, and especially in cold weather the formaldehyd precipitates as a white substance, which consists of one of the polymeric forms of formaldehyd known as trioxymeth- ylene. Formalin usually contains lo per cent, of wood alco- hol, which increases the solubility and stability of the formaldehyd. Hot formalin attacks iron and steel, and therefore cannot be used for the disinfection of such objects. It does not attack copper, brass, nickel, zinc, and other metallic sub- stances. In causes no diminution in the strength of textile fabrics, and has no bleaching or other deleterious effects upon colors. Formalin solution renders leather, furs and skins brittle as a result of the union that takes place between the formal- dehyd and the organic matter of these articles, and they should therefore be disinfected by another process. The formalin as found upon the market is acid as a rule, due probably to formic acid. For this reason the solution is apt to spot the delicate colors of silks and fine stuffs. Even water will do this. Such articles should be disinfected with formaldehyd gas. A 4 per cent, solution of formalin (containing 40 per cent, formaldehyd) in water is about the equivalent of a i : 1000 solution of bichlorid of mercury, or superior to a 5 per cent, solution of carbolic acid. It must be borne in mind that in speaking of a solution of formalin, a solution is meant of the liquid containing 40 per cent, formaldehyd. That is to say, a i per cent, solution of formalin would contain that liquid in the proportion of I to 100, but would contain the substance formaldehyd in the proportion of i to 250. Digitized by Microsoft® 1 62 DISINFECTION AND DISINFECTANTS. Feces are deodorized instantly by a 4 per cent, solution of formalin, and are rendered sterile at the end of ten minutes when mixed with an equal volume of a solution of this strength. According to Park and Guerard, a 3 per cent, solution will kill anthrax spores in fifteen minutes; a i per cent, solu- tion will kill all other germs in one hour, and most germs in thirty minutes. There is some discrepancy as to the percentage of formalin solution necessary to accomplish trustworthy disinfection in general practice. Taking into account the deterioration of the solution with age, and allowing an excess as an element of safety, it is recommended to use a 5 per cent, solution for the purposes of general disinfection. Formalin is very useful for the disinfection of urine, ex- creta, sputum, and other albuminous matters. It combines with, but does not coagulate, the albuminous matter, and penetrates deeply. Formalin is a true deodorant. It does not mask one smell with another, but unites with the albuminous matter to form new compounds that are both odorless and sterile. On account of the non-toxic properties of formaUn it may be used to disinfect certain kinds of food products. At quarantine stations large quantities of bulbs, roots, nuts, fruit, and similar articles coming from plague- or cholera- infected regions are disinfected by immersion in a 5 per cent, solution of formalin. This treatment does not injure their food value. Bulbs, roots, and fruit treated by this method will keep from rotting a much longer time than those not treated. There is a great difference between the antiseptic and the germicidal value of formalin. That is to say, a very minute amount — i in 25,000 or 50,000 — is sufficient to inhibit the Digitized by Microsoft® CHEMICAL SOLU'l'IONS. 1 63 growth and development of bacteria, whereas it requires a I to 4 per cent, solution to kill bacteria in a short time. A very minute trace added to milk or wine or other fluids will preserve them a long time from spoiling. Potassium permanganate is a germicide Potassium of undoubted power, but of very limited Per- application in general practice, on account MANGANATB. of the readiness with which it is reduced and rendered inert by organic matter. Even in weak solutions it destroys micro-organisms of high resistance, and despite its limitations it ranks high on the list of dis- infectants for certain definite purposes, more particularly in surgical practice and for the purification of water. Potassium permanganate (K^MnjOg) is a dark purple, crystalline substance, with a sweet astringent taste. A few crystals impart to a large quantity of water a rich purple tint, which is destroyed by organic matter and deoxidizing agents. It is soluble in i6 parts of cold and 2 parts of boil- ing water. The stains produced by potassium perman- ganate may be removed by a solution of oxalic acid, muriatic acid, or simple lemon juice. Potassium permanganate readily gives up its available - oxygen in contact with organic matter or oxidizable mineral substances, and it is the free nascent oxygen that is the true disinfecting agent. Unfortunately, as pointed out by Harrington, for its use as a general disinfectant a small amount of organic matter requires a very large amount of the salt for its complete oxidation. Thus, i ounce of liquid feces or of urine can reduce such an amount that it is esti- mated that the sterilization of the total twenty-four hours' excreta of one person would cost five dollars. Sternberg found a solution of 1 : 833 sufficient to kill pus Digitized by Microsoft® 164 DISINFECTION AND DISINFECTANTS. cocci in two hours. Koch found that a 5 per cent, solution killed spores in one day. Loeffler found the bacillus of glanders destroyed in two minutes by a i per cent, solution. Kronig and Paul * found that a i per cent, solution of potassium permanganate, with the addition of i per cent, hydrochloric acid, becomes an extraordinarily strong disin- fecting solution. Resistant anthrax spores are killed in two minutes. According to these authors this solution is not equaled by a 5 per cent, sublimate solution. Water contaminated by organic matter may be purified and rendered palatable by adding drop by drop a solution of permanganate until the pink color of the water ceases to be destroyed after the lapse of twenty-four hours. The clear liquid may then be decanted and used. On shipboard, in wells, and other places where there is a limited amount of water suspected of being infected with cholera, typhoid, or dysentery, enough of the permanganate is sometimes added to give the water a slight tinge of color. This method of purifying the water, which is in rather com- mon use in certain parts of the world, cannot be compared in efficiency with boiling. The strong solution may be used to disinfect the water-tanks and casks themselves. The toxicology of potassium permanganate is important on accountcf its use in drinking water. Internally 8 to 10 grains have been taken, without injury, in a very dilute solution. Two grains have produced S5'mptoms of an irritant poison. Lime, or quicklime, is a very caustic sub- LiMB. stance, useful for the destruction of organic matter as well as germ life. On account of its efficiency and cheapness it is a valuable addition to the list of practical disinfectants. * " Zeitschr. f. Hygiene,'' Bd. XXV, 1897, p. 89. Digitized by Microsoft® CHEMICAL SOLUTIONS. 1 65 Lime, or calcium oxid (CaO), also known as quicklime, is one of the alkaline earths. It is not so caustic as the alka- lies, having a less afi&nity for water. It is obtained by cal- cining native calcium carbonate (CaCOj), such as chalk, limestone, or marble, by which the carbon dioxid is given off and the calcium oxid (lime) remains behind. Slaked lime, or calcium hydrate (Ca(0H)2), is prepared by adding one pint of water to two pounds of lime. The lime absorbs about half its weight of water. The mass becomes heated and the air escapes from the pores of the lime with a hissing noise. The result is calcium hydrate or slaked lime. Exposed to the air, the slaked lime will absorb still more water and also carbon dioxid, converting it into cal- cium carbonate, which is inert so far as its disinfecting power is concerned. Freshly slaked lime should therefore always be used. Whitewash is slaked lime mixed with water. It is com- monly used for the disinfection, sweetening, and brightening of the walls of cellars, rooms, barracks, barns, stables, poul- try houses, and out-buildings generally. Whitewashing is a satisfactory method of destroying disease germs that may have lodged upon such surfaces. Milk of lime is slaked lime mixed with about four times its volume of water, to the consistency of a thick cream. It is useful in the disinfection of excreta and privy vaults. Air-slaked lime must not be used in the preparation of white- wash or the milk of lime, freshly slaked lime being necessary to accomplish disinfection. Calcium hydrate is insoluble and settles to the bottom; the milk of lime must therefore be agitated to restore its homogeneous character before it is used. MUk of lime is most powerful when freshly pre- pared. In contact with the air it changes to the inert carbonate, and should therefore not be used if more than Digitized by Microsoft® 1 66 DISINFECTION AND DISINFECTANTS. a few days old, unless carefully protected from contact with the air. The researches of numerous scientists, though differing somewhat in certain unimportant particulars, have con- firmed the conclusions of the earlier investigators as to the great practical value of lime as a germicide. Liborius * demonstrated the value of lime in the destruction of the bacteria of typhoid fever and cholera. He found that lime- water containing 0.0074 per cent, destroyed the former in a few hours, and lime-water containing 0.0246 per cent, de- stroyed the latter in the same time. Cholera bouillon cul- tures, containing numerous coagula of albumin, such as would be present in cholera discharges, were completely disinfected within the course of a few hours by 0.40 per cent, of pure lime or 2 per cent, of ordinary crude lime. He recommended the employment of the pure dry powder or of mUk of lime containing 20 per cent, of crude lime. Similar favorable results have been obtained by many other workers. Lime is particularly valuable in the disinfection of excreta. The lime in one form or another must be well incorporated with the mass, and enough must always be added in order to make the reaction of the mixture distinctly alkaline. Sternberg recommends the freshly prepared milk of hme containing about i part by weight of hydrate of lime to 8 parts of water. This should be used freshly prepared and added in quantity equal in amount to the material to be disinfected. The mixture should be allowed to stand at least two hours before final disposal. Fortunately, this valuable disinfecting agent is very cheap, so that it can be used with a liberal hand in excess of the amount which scientific tests find necessary. * " Zeitschr. f. Hygiene," 11, p. 25, quoted by Harrington, p. 504. Digitized by Microsoft® CHEMICAL SOLUTIONS. 167 I/ime has been used in very early times in connection with the disposal of the dead. The method is an admirable one for the burial and disinfection of bodies dead from a contagious or infectious disease. The body should be surrounded, in a tight coffin, with twice its weight of fresh unslaked lime, without the addition of water or moisture in any form. Chlorinated lime was used as a disin- Chlorinated fectant and deodorant long before bacteri- I/IME — ology was a science. The work of Sternberg Ghloride; of ably proved that the confidence placed in I/iME. this substance from an empiric standpoint is justified by scientific tests. Chlorinated lime ranks about with unslaked lime in power and value as a germicide, and has about the same uses in practical dis- infection. Chlorinated lime, popularly miscalled "chloride of lime," is a soft, white, friable substance, and is known also as bleaching powder. It has a peculiar chemical composition and is somewhat unstable. Owing to its affinity for mois- ture, which it slowly absorbs from the air, it becomes pasty and loses some of its chlorin. Freshly prepared chlorinated lime should have a very slight odor of free chlorin. A strong odor of this gas indicates that decomposition of the sub- stance is taking place, and the loss of chlorin sensibly di- minishes its disinfecting power. It should therefore only be used when freshly prepared, or when kept in air-tight recep- tacles. Chlorinated lime is made by passing nascent chlorin gas over moist calcium hydrate (unslaked lime). Concerning its exact chemical composition there is some disagreement. It is represented by the formula CaOClj, or ClCaOCl, or Ca(C10)Cl. According to the United States Pharmacopeia Digitized by Microsoft® 1 68 DISINFECTION AND DISINFECTANTS. it should contain not less than 35 per cent, of available chlorin. The British standard is 33 per cent., and the Ger- man 25 per cent. It is very insoluble in water ; only about a i per cent, solu- tion can be made. The solution has an indefinite composition, but is gener ally admitted to contain calcium hypochlorite (CaClCaClOj), which is its principal disinfecting constituent ; calcium chlo- rid (CaClj), which has a great affinity for water, and calcium hydrate, Ca(0H)2, which is largely insoluble. The calcium hypochlorite, upon which the efficiency of the solution largely depends, is readily broken up, even by the carbon dioxid found in the air and water, into hyperchlorous acid, and this acid is so unstable that even in the presence of light it is decomposed into hydrochloric acid and free chlorin, both of which are active germicides. The solution is highly alka- line and has feeble bleaching powers. Its action as a deodorant depends not only upon its de- structive influence upon organic matter and its germicidal properties, but also upon its great affinity for water, thus acting as a desiccant ; as well as upon its power of combining with hydrogen sulphid and the volatile ammoniacal com- pounds of decomposition and decay. Chlorinated lime not only bleaches, but is destructive to fabrics. If the solution is employed for the disinfection of infected bed linen and washable clothing these articles must, after a not too long immersion, be most thoroughly washed in plenty of fresh water. A solution known as the "American Standard," containing ,6 ounces of the powder to the gallon, is largely used for the disinfection of discharges and for the scrubbing of floors and other woodwork. The chlorinated lime may be used either as a dry powder or in solution. As a dry powder it is very generally used by Digitized by Microsoft® CHEMICAL SOLUTIONS. 1 69 strewing it in damp corners of cellars, privies, and similar places, where it acts as a deodorant and desiccant. The dry substance may also be used to disinfect excreta. For this pur- pose enough of the chlorinated lime must be added and well incorporated with the mass to make a 4 per cent, solution. In the United States Army a 4 per cent, strength of chlor- inated lime in solution is officially prescribed for use in the disinfection of the excreta of the sick, it being specially stated that the chlorinated lime so used should be of good quality and not have undergone decomposition. Chamberland and Pernbach * advise that the solution of chlorinated lime be made by covering one part of the bleach- ing powder with an equal amount of water. After standing an hour the mixture is filtered and a greenish-yellow liquid obtained. One part of this solution is added to ten times its volume of water, for application to the surfaces to be disinfected. As a result of their investigations it is claimed that for purposes of disinfection this weak solution is fully as efficacious as a stronger one. If possible, the solution should be applied hot, and the room which is being disin- fected should also have its temperature elevated. Calcium hypochlorite (CaClOj) is one of The Hypo- ^^'^ disinfecting substances found in the CHLORiTES — aqueous solution of chlorinated lime, and it Labarraque's has just the same uses as that solution. Solution. According to Reed, calcium hypochlorite must have a chlorin strength of 0.25 per cent., otherwise it cannot be relied upon as a disinfectant. I^abarraque's solution is an aqueous solution of several chlorin compounds of sodium, chiefly sodium hypochlorite * Munson, " Military Hygiene," p. 780. Digitized by Microsoft® 170 DISINFECTION AND DISINFECTANTS. (NaClO) and sodium chlorid (NaCl), and should contain at least 2.6 per cent, by weight of available chlorin. The solu- tion is clear and colorless when pure. If prepared with an excess of chlorin it is yellowish in color. It has a feeble odor of chlorin and bleaches indigo, litmus, and vegetable dyes like chlorin gas, but less energetically. Its germicidal properties depend upon the liberation of the chlorin set free by the decomposition of the sodium hypochlorite. In practice this solution diluted with water (i to 4) is mainly used for the disinfection of the person, but as it is more expensive and somewhat less efficient than the solu- tions of chlorinated lime, it has no advantages over that substance. Ferrous sulphate has long been valued Ferrous as a disinfectant on account of its power Sulphate, as a destroyer of bad odors, and has been extensively used, being a comparatively cheap substance. Its germicidal power has been shown by laboratory tests to be very feeble, even in strong solutions, so that it cannot be depended upon as a trustworthy dis- infectant. Ferrous sulphate, FeSO^, commonly called green vitriol, iron vitriol, or copperas, consists of large bluish-green crystals which slowly effloresce and oxidize in the air. It is soluble in about twice its weight of cold water. Miquel places its antiseptic power at i : 90. Sternberg found that in solutions of i : 200 it failed to prevent the development of micrococci, and of putrefactive bacteria in bouillon placed in the incubator over forty-eight hours. Ivcitz found that a 5 per cent, solution required three days' exposure for the destruction of the typhoid bacillus. Koch Digitized by Microsoft® CHEMICAL SOLUTIONS. 171 found that a 5 per cent, solution failed to destroy anthrax spores in six days. Ferrous sulphate, therefore, judging from the evidence before us, has no claims to be considered a germicide, and has such feeble disinfecting powers that it cannot be de- pended upon to destroy the contagium, even of non-spore- bearing infections. At best, then, ferrous sulphate is limited in use to the destruction of the odors arising from fecal matter, and even for this purpose it is not always successful, for Foote * has shown that it sometimes makes a bad odor worse, through chemical action on organic compounds produced in the pro- cess of putrefaction. Munson points out the fact that it does not impair the fertilizing value of matter to which it is ap- plied. In practice he recommends 5 parts of the iron salt for each 100 parts of the total contents of the latrine vault as essential to efficiency. The salt must always be applied in solution, and thoroughly incorporated with the mass. In the French army ferrous sulphate is much used for the dis- infection of latrines in a 10 per cent, solution. It is officially laid down that at least 250 c.c. of such a solution should be used per day for each person using the latrine. Zinc chlorid was at one time highly valued Zinc as a disinfectant and is still extensively used, ChIvOrid. despite the fact that it stands rather low in the list of germicidal agents. It has even weaker powers as a disinfectant than ferrous sulphate, and cannot be recommended as trustworthy. It has some value as a deodorant. Chlorid of zinc, ^nCl, is a white, translucent; friable sub- stance, very soluble in water and very deliquescent. It is *" Amer. Jour, of the Med. Sci.," xc, p. 329. Digitized by Microsoft® 172 DISINFECTION AND DISINFECTANTS. a strong dehydrating substance and removes oxygen and hydrogen from organic bodies in the form of water, which partly explains its action as a deodorant, as well as its effect upon germs. According to Miquel, it is antiseptic — that is, prevents the growth and multiplication of bacteria in the proportion of I : 526. Koch found that anthrax spores germinated after being immersed in a 5 per cent, solution for thirty days. Sternberg found that a solution of the strength of i : 200 destroyed Micrococci pasteuri in two hours. Ordinary soaps have a limited disinfecting Soaps. power. According to Behring,* this depends upon their alkalinity; but Serafitnif more correctly points out that the free alkali present, even in con- centrated soap solutions, is so small in amount that it can exert no disinfecting action whatever, and that neither the' alkali nor the fatty acid, but the combination of the two, is the effective agent. Unfortunately, the disinfecting power of soap solutions is not marked enough to make them trustworthy disinfect- ants, despite their great value as detergents. The common commercial soaps, especially the colored soaps, are frequently of very poor quality, containing rosin instead of the fatty acids, and are not to be depended upon. The soft soaps should also be avoided on account of the presence of all the impurities of the fat and alkali from which they are made. There are other conditions which render the use of soaps uncertain, the chief of which is the hardness of the water. The laboratory experiments of numerous investigators have shown that soap solutions have a decided power to * " Zeitschr. f. Hygiene," Bd. IX, 1890, p. 414. t " Archiv f. Hygiene," XLili, 1899, p. 369. Digitized by Microsoft® CHEMICAL SOLUTIONS. I 73 destroy some of the less resistant forms of bacteria. It has also been shown that soap, even in strong solution and with prolonged exposure, cannot' be trusted to destroy the in- fection of typhoid fever, cholera, or the micrococci of sup- puration. The action of soap solutions is much influenced by the temperature, which is easy to understand when we recall the powerful action of hot water alone upon bacterial life. Therefore soaps alone cannot be depended upon for the certain disinfection of objects and clothing, but in solution with hot water as usually applied, and especially in con- junction with certain compatible chemicals, and also with the mechanical cleansing which almost always accompanies their application, this substance has a wide and varied use- fulness. Soap solutions should always be made with a soft water. The addition of one of the caustic alkalies, as lye, increases its germicidal and detergent value. The solution should be strong, containing not less than lo per cent, of soap, and the water should be as hot as possible and applied with mops or brushes so as to aid the solvent action of the sub- stance upon the oleaginous and albuminous matter clinging to dirty surfaces or fabrics. Medicated soaps are for the most part a snare and a delu- sion so far as any increased germicidal action is concerned; in fact, the addition of carbolic acid, bichlorid of mercury, and other substances which have the property of combining with the soap, seems actually to diminish the disinfecting value of that substance. As a rule a very small quantity of the disinfecting substance is added to the soap, and when it is called to mind what an exceedingly small quantity of soap is necessary for the ordinary washing of the skin, and the further dilution of this small amount by the water used, Digitized by Microsoft® 174 DISINFECTION AND DISINFECTANTS. it is easy to understand that medicated soaps, as ordinarily applied, cannot have an energetic disinfecting action. An exception seems to be the soap devised by McClintock,* in which the mercury salt exists unchanged and active. He found that the double iodid of mercury answers these pur- poses in the proportion of 0.5 to 2.0 per cent. A solution containing i per cent, of the soap was found by him to be fatal for pus cocci, cholera, diphtheria, and typhoid fever bacilli in one minute. The soap does not attack nickel, silver, aluminium, steel instruments, or lead pipes, and does not coagulate albumin. *" Disinfection and Disinfectants," London, 1898, p. 347. Quoted by Harrington. Digitized by Microsoft® CHAPTER IV. INSECTICIDES APPLIED TO DISINFECTION AGAINST THE INSECT-BORNE DISEASES. Arsenic — Petroleum — Bisulphid of Carbon — Pyrethrum — Sul- phur — Formaldehyd Gas — Hydrocyanic Acid Gas — Danyz' Virus and Other Rat Poisons. Practically all the germicidal agents are also insecticides. There are some exceptions to this statement, notably for- maldehyd, which is one of our most potent germicides, but has little or no effect upon insect life. As the fly, mosquito, flea and other insects are known or suspected of conveying the infection of some of the communicable diseases, it is important that the disinfec- tor know how best to destroy this class of vermin. The general subject of protecting the individual against the bites, dangers and annoyances of mosquitos, flies, etc., and the subject of ridding a community of this dangerous class of vermin, although a very important one from an economic and hygienic standpoint, cannot be discussed in the limits of these pages. These questions belong more to the sanitarian than to the disinfector. Only those agents are considered which are useful to the disinfector in exterminating vermin in a room or building, in order to prevent the spread of disease. The mosquito is known to transmit the infection of several diseases. This insect is the intermediate host for the parasites of malaria, yellow fever and filariasis. The "75 Digitized by Microsoft® 176 DISINFECTION AND DISINFECTANTS. micro-organisms are taken into the stomach of the mosquito with the blood it sucks. From the stomach the parasites pass into the general body cavity or the glands of the mosquito, and are extruded again through the insect's proboscis under the skin of its victim. That is to say, the mosquito inoculates the infectious principles into the system just as we would experimentally inoculate an animal by means of a hypodermic syringe. On the contrary, the fly, ant, flea and other insects transmit the infection of disease in quite another way. For instance, flies spread the infection of typhoid fever, cholera, plague and anthrax smeared upon their legs and upon the external surfaces of their bodies. This is readily understood when we recall the habit of flies feeding upon and breeding in decomposed meat, dejecta and other matters apt to contain the infectious principles of the above-named diseases. The investigation of the Army Medical Commission during the Spanish-American war practically established the fact that the fly is an important factor in the dissemi- nation of typhoid fever. Victor Vaughan, a member of that commission, stated that flies undoubtedly served as carriers of typhoid in- fection, giving the following as reasons for his belief: " They swarmed over fecal matter in the latrines. They visited and fed on food prepared for the soldiers in the mess tents. In some instances, when lime had been recently sprinkled over the contents of latrines, flies with their feet whitened with lime were seen walking over the food. Officers, whose mess tents were protected by means of screens, suffered less proportionately from typhoid fever than those whose tents were not so protected. Typhoid fever gradually disappeared in the fall of 1898, with the Digitized by Microsoft® INSECTICIDES. 177 approach of cold weather and the consequent disabHng of the fly." It is perfectly easy to understand how a fly, alighting upon the skin of a smallpox patient, and contaminating its legs, proboscis and body with the fluid exudate from the vesicles and pustules, may carry this highly infectious material to other persons in the same house or to neighbor- ing houses. Flies, fleas, ants and other insects spread the infectious principles of many communicable diseases in another way than simply this mechanical conveyance of the bacteria upon their external parts. These insects feed upon organic matter containing the infective principles, which live a variable length of time in their intestinal canals, and the live and virulent micro-organisms are deposited with the dejecta. In this way infection is transmitted from infected materials to man, from animals to man, and from man to man. It is believed that the biting insects, such as flies, fleas, ants, etc., do not inoculate the parasites under the skin when they bite. When this does occur, it is probably due to an accidental contamination of the mouth or biting parts of the insect with the infective germs. In other words, the transference seems to be mechanical. The insect does not act as an intermediate host, and the bac- teria do not pass through various phases of development in the insect, as is the case with the malarial parasite and the mosquito. The flies, fleas, ants, etc., deposit the infectious material on the skin with their excrement, and in other ways. The virulent infection is rubbed into the little wounds or scratched into the skin as a result of the irritation caused by the bites, thereby setting up the disease. Digitized by Microsoft® 178 DISINFECl'ION AND DISINFECTANTS. For the reason that plague is transmitted through the agency of rats, a paragraph is introduced upon the means commonly employed to destroy these rodents. The arsenical compounds, according to Arsenic. Marlatt,* have supplanted practically all other substances as a food poison for biting insects. The two arsenicals in most common use and obtainable everywhere are Paris green and London pur- ple. Scheele's green and arsenite of copper are less known and less easily obtainable, but in some respects are better than the first-mentioned poisons, as will be shown later. The use of powdered white arsenic is not recom- mended on account of its corrosive action, as well as the fact that it is apt to be mistaken for harmless sub- stances. Paris green is a definite chemical compound of arsenic, copper, and acetic acid (known as the aceto-arsenite of copper), and should have a nearly uniform composition. It is a rather coarse powder, or, more properly speaking, crystal, and settles rapidly in water, which is its greatest fault so far as the making of suspensions of this substance is con- cerned. The cost of Paris green is about 20 cents per pound. Scheele's green is similar to Paris green in color and differs from it only in lacking acetic acid ; in other words, it is simply arsenite of copper. It is a finer powder than Paris green, and therefore is more easily kept in suspension, and has the additional advantage of costing only half as much per pound. London purple is a waste product in the manufacture of * Farmers' Bulletin No. 19, "Important Insecticides," by C. L. Marlatt, 1898, U. S. Dept. of Agriculture. Digitized by Microsoft® INSECTICIDES. 1 79 anilin dyes, and contains a number of substances, chief among which are arsenic and lime. It is quite variable in the amount of arsenic it contains and therefore is not so effective as the green poisons. It comes in a fine powder and is more easily kept in suspension than Paris green. It costs about 10 cents a pound. Arsenite of lead is prepared by combining, approximately, 3 parts of the arsenite of soda with 7 parts of the acetate of lead (white sugar of lead) in water. These substances, when pulverized, unite readily and form a white precipitate, which is more easily kept suspended in water than any of the other arsenical poisons. Bought wholesale the acetate of lead costs about 7^ cents a pound, and the arsenite of soda costs about 7 cents a pound. Its use is advised where excessive strengths are desirable and upon delicate plants where other- wise scalding is likely to result. The arsenical poisons may be applied in one of three ways : (i) in suspension, as poisoned waters, mainly in the form of sprays; (2) as a dry powder blown or dusted about the infested areas; or (3) as poisoned bait. It must be remembered that the arsenicals are very poi- sonous, and should be so labeled, and care taken to prevent accidents. An average of one pound of either Paris green, Scheele's green, or I^ondon purple to 150 gallons of water is a good strength for general purposes in using the wet method. The powder should first be made up into a thin paste in a small quantity of water, and if the suspension is to be used upon plants, vegetables, or about foliage, an equal amount of quicklime should be added to take up the free arsenic and remove or lessen the danger of scalding. For the distribution of dry poison the arsenicals are di- luted with 10 parts of flour, lime, or dry gypsum. 13 Digitized by Microsoft® l8o DISINFECTION AND DISINFECTANTS. Petroleum, kerosene or coal oil is a very Petroleum, valuable insecticide, but of limited appli- cation, as it must be used in liquid form, its vapor being too inflammable for consideration in this connection. As a remedy for mosquitos kerosene has proved very effective when applied as recommended by L. O. Howard. It is employed to destroy the larvge of the mosquitos in pools, still ponds, stagnant water, water buckets, and other small collections of water not of value for their fish. In large bodies of water it is not nearly so effective, as the oil is blown about by the wind, thereby uncovering the greater portion of the surface. An apparatus devised by Dr. Doty is of use in distributing the petroleum over the surface of ponds. It consists of a wooden framework carrying the oil pipes which deliver the petroleum through many small openings projecting 6 inches or so below the surface of the water. The float is drawn over the pool while the petroleum is allowed to escape, thus coating the entire surface, and emulsifying some of the oil with the water, which intensifies its insecticidal action. The petroleum is applied at the rate of i ounce to 15 square feet of water surface. It forms a uniform film over the surface and destroys all forms of aquatic insect life, includ- ing the larvae of the mosquito and the adult females coming to the water to lay their eggs. The oil must be renewed every few weeks, depending upon the temperature and other circumstances. A light grade of fuel oil is recommended by Howard for this purpose. Petroleum is also useful against roaches, bedbugs, and other forms of insect vermin when used by direct applica- tion or by spraying either in the form of the pure oil or as an emulsion with water, soap, or milk. Digitized by Microsoft® INSECTICIDES. l8l Bisulphid of carbon (CS2) is a very effi- B1SUI.PHID OF cient insecticide, but a dangerous one on Carbon. account of its inflammable and explosive nature. When pure it is a mobile, colorless liquid, with an agreeable ethereal odor; but often it has a more or less fetid odor from the presence of other volatile compounds. The liquid must be kept in well-stoppered bottles, in a cool place away from the light and fire. It evaporates very rapidly at the ordinary temperatures, so that in using this substance in a confined space it is suffi- cient to pour it into open pans and it will quickly pass into the air as a gas, in which state it is an efficient insecticide. It is very inflammable — more so than ether — and burns with a pale blue flame, yielding sulphur dioxid and carbon dioxid or monoxid. Upon the authority of Howard and Marlatt,* this sub- stance, distributed about a pantry or room in open vessels, will evaporate and if used in sufficient quantity will destroy roaches and other vermin. Unless the room can be very tightly sealed, however, the vapor dissipates so rapidly that its effects will be lost before the roaches are killed. In the use of this substance every precaution must be taken to see that there is no fire, lighted cigar, etc., in or about the premises during the treatment, on account of its inflammable and explosive nature. It is also deadly to the higher animals, so that apartments should be thoroughly aired after its use. According to Hinds, f shallow tin pans or plates make good evaporating dishes for carbon bisulphid. The larger * " The Principal Household Insects of the United States," Bulletin No. 4, new series, revised edition, U. S. Dept. of Agriculture, 1896. t Farmers' Bulletin No. 145, U. S. Dept. of Agriculture, "Carbon Bi- sulphid as an Insecticide," by W. E. Hinds, 1902. Digitized by Microsoft® 1 82 DISINFECTION AND DISINFECTANTS. the evaporating area, the better. There should be about one square foot of evaporating surface to every twenty- five square feet of floor area, and each square foot of evaporating surface should receive from one-half to one pound of liquid. These figures are, of course, only sug- gestive and approximate. Pans should be placed as high in the room as possible, since the vapor is so heavy that it settles most heavily to the lower parts. Care should be taken, when placing the pans, to see that they are nearly level, so as to hold the liquid, though ordinarily no par- ticular harm will be done if some of it is spilled. It should not be found necessary to lose time in adjusting such things after the application is begun. If there are special places which are difificult of access or treatment with the pans, cotton waste, bundles of rags, or the like may be saturated and thrown into these places. Everything should be done to avoid unnecessary delays and to facilitate the rapid exposure of the liquid. If the liquid is bought in large quantities, smaller receptacles may have to be provided for transferring it to the pans. Pyrethrum is a popular and much used PyrBThrum. insecticide because it is comparatively cheap and non-poisonous to the higher animals, but unfortunately it is not very powerful for the destruc- tion of roaches, ants, mosquitos, bedbugs, fleas, flies, etc. Pyrethrum, also sold under the names of Buhach and Persian insect powder, or simply insect powder, is the flowers of the Chrysanthemum roseum and the Chrysanthemum carneum, both hardy perennials and resembling chamomile in appearance. According to Kalbrunner,* 4 grains of the pure powder *U. S. Disp.,p. 1334. Digitized by Microsoft® INSECTICIDES. - 1 83 Sprinkled on a fly in a vial should stupefy it in one minute and kill it in two or three minutes. This is used as a test for the strength of pyrethrum. It acts on insects externally through their breathing pores, and according to Marlatt,* is fatal to many forms of biting and sucking insects, being chiefly valuable against house- hold pests, such as roaches, flies, and ants. It is used either as a dry powder or by its burning fumes. As a dry powder it may be used pure or mixed with flour, in which form it should be puffed about the room, especially into the cracks. Against mosquitos the powder should be burned in the room, and if used in sufficient strength and for a sufficient length of time, it will kill many of these in- sects, but it cannot be depended upon for the destruction of mosquitos infected with yellow fever, for some of the insects are only stupefied. They must be gathered up and destroyed after the fumigation. The regulations of the United States army require the burning of five pounds of the pyrethrum powder for each 1000 cubic feet of air space, for the destruction of mosquitos in confined spaces. Sulphur is one of the most valuable in- SuLPHUR. secticides we possess. It may be used in several forms. Sulphur dioxid gas produced and used according to the methods given for bacterial disinfection will kill roaches, bedbugs, mosquitos, flies, fleas, and all kinds of vermin, in- cluding rats and mice. This substance is therefore exceed- ingly useful in disinfecting for such diseases as plague, yellow fever, malaria, and insect-borne infections. * " Important Insecticides," Fanners' Bulletin No. 127, p. 15. Digitized by Microsoft® 184 DISINFECTION AND DISINFECTANTS. The methods of producing the gas by burning sulphur, or by Hberating the liquefied sulphur dioxid, the time of exposure, and all important directions concerning the appli- cation of this substance to jjractical disinfection will be found on page 118. The time of exposure necessary to kill insects and vermin is shorter than that given for sulphur dioxid as a germicide. One hour is ample for mosquitos, and two hours for rats. Very dilute atmospheres of the gas will quickly kill mos- quitos. It is quite as efficacious for this purpose when dry as when moist, whereas the dry gas has practically no power against bacteria. Contrary to formaldehyd, it has surpris- ing powers of penetrating through clothing and fabrics, killing the mosquitos, even when hidden under eight layers of toweling, in one hour's time and with very dilute proportions. This substance, which has so long been disparaged as a disinfectant because it fails to kill spores, must now be con- sidered as holding the first rank in disinfection against insect- borne diseases. The flowers of sulphur is very efficient in its powdered state as an insecticide. It may be applied in several forms, the simplest of which is to merely sprinkle the dry sulphur about the places where the insects are found. The flowers of sulphur may also be advantageously combined with other insecticides, such as kerosene emulsion, resin wash, or a soap wash, mixing it first into a paste and then adding it to the spray tank in the proportion of from i to 2 pounds to 50 gallons. The sulphur in its dry form must be directly applied to the places where the insects are found, and is used more for the destruction of the mites and rust of plants and fruit. It has but a limited use against bedbugs, ants, roaches, etc., and is practically useless against the winged insects. Digitized by Microsoft® INSECTICIDES. 185 Disulphid of lime is a good liquid insecticide where a liquid is applicable. It may be very cheaply prepared by boiling together for an hour or more, in a small quantity of water, equal parts of the flowers of sulphur and stone lime. A convenient quantity is prepared by taking 5 pounds of sul- phur and 5 pounds of lime, and boiling in 3 or 4 gallons of water until the ingredients combine, forming a brownish liquid. This may be diluted to make 100 gallons of spray. Formaldehyd gas, while holding the front FoRMALDEHYD rank as a germicide, is a feeble insecticide. Gas. It seems to have no effect whatever upon roaches, bedbugs, and insects of this class, even after prolonged exposure to very high percentages of the gas. While very irritating, this substance is not toxic for the higher forms of animal life. (See page 87.) Mosquitos * may live in a very weak atmosphere of the gas overnight. It will kill them, however, if it is brought in direct contact in the strength and time prescribed for bacterial disinfection. For this purpose any of the accepted methods for evolving the gas is applicable, but the methods which liberate a large volume in a short time are more cer- tain than the slower ones. Direct contact between the insects and the gas is much more difficult to obtain in ordinary room disinfection against mosquitos than against germs, because the sense of self -pro- tection helps the former to escape from the effects of the irritating gas. They hide in the folds of towels, bedding, clothing, hangings, fabrics, and out-of-the-way places where the formaldehyd gas does not penetrate in sufficient strength to kill them. The gas is polymerized and deposited as para- * " Disinfection against Mosquitos," Rosenau, Laboratory Bulletin No. 6, Marine Hospital Service. Digitized by Microsoft® 1 86 DISINFECTION AND DISINFECTANTS. form in the meshes of fabrics, which prevents its penetration, and large quantities are lost by being absorbed by the organic matter of fabrics, especially woolens. In our tests, when- ever the insects were given favorable hiding-places, such as in crumpled paper or in toweling, they quickly took ad- vantage of the best place for themselves and often escaped destruction. There is a striking analogy between the strength of the gas and the time of exposure necessary to penetrate the fabrics in order to kill mosquitos, and the strength and time neces- sary to penetrate in order to kill the spores of bacteria. Mosquitos have a lively instinct in finding cracks or chinks where fresh air may be entering the room, or where the gas is so diluted that they escape destruction. They are able to escape through incredibly small openings. Some of the smaller varieties, such as the Stegomyia fasciata, can get through a wire screen having twelve meshes to the inch. Therefore, formaldehyd gas cannot be trusted to kill all the mosquitos in a room which cannot be tightty sealed. It is concluded that to succeed in killing all the mosquitos in a closed space with formaldehyd gas, the following definite requirements are essential: A very large volume of the gas must be liberated quickly, so that it may diffuse to all por- tions of the space in sufficient concentration. The room must have all the cracks and chinks where the insects may breathe the fresh air carefully sealed by pasting strips of paper over them. The room must not contain heavy folds of drapery, clothing, bedding, or fabrics in heaps, or so disposed that the insects may hide away from the full effects of the gas. For the methods of evolving formaldehyd gas, the quan- tities to be used, and other details of the process, see Chapter II. Digitized by Microsoft® INSECTICIDES. 1 87 Hydrocyanic gas is extremely poisonous Hydrocyanic to all forms of life. It kills roaches, bed- AciD Gas. bugs, mosquitos, fleas, flies, rats, and mice with great certainty and very quickly. It is much less poisonous to the vegetable forms of life, as has been discussed under the use of this gas as a germicide (page 137). The gas is much used in greenhouses for the destruc- tion of insect pests, and for the scale insects and other para- sites of fruit trees. Hydrocyanic acid gas has a distinct place in the disinfec- tion of granaries, stables, ships, barns, outhouses, and other uninhabited structures infested with vermin. But it should not be used in the household, or any other inhabited build- ing, as the least carelessness with it would probably mean the loss of human life. For the methods of evolving the gas and other details see page 138. The ordinary methods of catching rats The ^^ such means as cats, dogs, ferrets, traps. Destruction poisoned bait, etc., are all useful in ridding OP Rats on a locality of this rodent. Account in Glasgow, Japan, and other places where OF i'l^AGUE. plague prevailed as an epidemic, thousands of rats, many of them infected with plague, were caught and disposed of, by the authorities offering a price upon their heads. Experience has shown that this reward must not be too large, else persons will breed the rodents as a paying investment. While the extermination of the rats in a city or a com- munity of considerable size may be a hopeless undertaking, their destruction on board an infected ship, in a stable, 14 Digitized by Microsoft® 1 88 DISINFECTION AND DISINFECTANTS. granary, or other limited area, is quite possible, although it takes time, care, and much patience. The handling and final disposition of rats suffering with or dead of plague is a matter requiring special care in order to guard against the infection. According to Simond, the fleas transmit the infection from the rats to man. He states that the flea will not leave the rat for man as long as the body of the rat is warm. Therefore, in the handling of rats, whether dead or alive, the hands should be protected with gloves and other precautions taken to guard against the fleas. The bodies of the dead rats should be cremated at once, and all surfaces exposed to the infection disinfected with a bichlorid solution or carbolic acid. The rats on board a ship or in a confined structure may best be destroyed by sulphur fumigation. Careful search must be made for the dead bodies. This same substance is useful in destroying or in driving the rats out of a sewer, in fighting the infection of plague in municipalities. For this purpose the sulphur is burned in the sulphur furnace and the fumes are driven into the sewer by a centrifugal fan. (See page 127.) Rats may also be killed in a confined space by the use of other poisonous gases, such as hydrocyanic acid gas, carbon bisulphid, or even carbon dioxid. Formaldehyd gas cannot be trusted to destroy these animals. The methods of using hydrocyanic acid and carbon bi- sulphid have been given in another portion of this chapter. The carbon dioxid is evolved by simply burning charcoal in open fires, and taking care to close the room or hold of the vessel very tightly. The substance known as Danyz' virus is sometimes useful in helping to rid a locality of these rodents. This virus Digitized by Microsoft® DESTRUCTION OF RATS. 1 89 consists of a culture of a bacillus belonging to the para colon group. It appears to be identical with Bacillus typhi mu- rium of lyoeffler. This organism is naturally pathogenic for mice, in which rodents it sometimes produces spontaneous epizootics. Its virulence has been raised and specialized by artificial means in the laboratory, so that it has become fatal for rats by ingestion. This artificial virulence is not very stable. It may be maintained under special conditions a few months, but the virulence is apt to fall off, especially on exposure to light and air. So far as rats are concerned, the effect depends somewhat on the amount ingested. Large amounts are frankly fatal. Small quantities are uncertain. Rats that survive the in- gestion of the virus are rendered immune. Such rats may eat large amounts of the virulent virus with no untoward effect. The infection caused in rats by eating the virus has feeble power of propagating itself from rat to rat. It, therefore, cannot produce a widespread epizootic among these rodents. In practical use it must be spread around so that as many of the rats as possible will eat it. In many respects it resembles a chemical poison, with this great advantage, viz., that it is harmless, so far as known, to man and domestic animals. It has the great disadvantage that chemical poisons do not possess, of render- ing the animals immune by the ingestion of amounts that are insufficient to kill, or by the ingestion of cultures that have lost a little of their virulence. In my experiments I succeeded in killing less than half the number (46 out of 115) of rats fed. The conditions in a cage are so much more favorable for the fatal action of the virus than could possibly be the case in nature that it is Digitized by Microsoft® 19° DISINFECTION AND DISINFECTANTS. safe to assert that a less number would succtimb in a wild state. The virus may, therefore, be used as one of the means in the fight against rats, but it is far from being a sure means of exterminating these rodents in a particular place. Digitized by Microsoft® CHAPTER V. DISINFECTION OF HOUSES, SHIPS, AND OBJECTS. The following objects, arranged alphabetically, are those commonly requiring treatment by the disinfector, and a brief outline of the special methods applicable to each. object is given. The principles involved and the details of the methods are given in full in other portions of the book and are not repeated in this chapter. It is quite impossible to disinfect the air Air. of a room during its occupancy by the pa- tient. Any of the known volatile substances in sufficient concentration to kill the micro-organisms would make life unbearable. It is therefore absurd to place such substances as carbolic acid, chlorinated lime, or formalin in an open pan in the sick-room or the water-closet, with the idea that they are serving a useful purpose in disinfecting the atmosphere or in preventing the spread of infection. The infection of few, if any, of the communicable diseases is given off in the exhaled breath. The exhaled breath is always sterile no matter how many microbes may be con- tained in the inhaled air. That is, the process of respi- ration acts as a bacterial filter for the atmosphere. When the air becomes infected, it is usually in an indirect way. From smallpox and the exanthemata the infection is given off into the air from the patient mainly in the fine particles of epidermis that float about the compartment with the 191 Digitized by Microsoft® 192 DISINFECTION AND DISINFECTANTS. dust. From tuberculosis and diphtheria the infection may float into the air from the dried sputum. The atmosphere surrounding the patient may also become contaminated with the germs of tuberculosis, diphtheria, the pneumonic form of plague, and other diseases in which the infection is discharged from the body in the expecto- ration, by coughing, sneezing, speaking, etc. In these ex- plosive expiratory movements, a fine spray is thrown several feet from the mouth, and may be carried with the currents of the air to all portions of the room. The infection of some diseases is carried in the air, in the bodies of mosquitos, or on the bodies of flies, instead, as was formerly supposed, as a miasm or poison directly vitiat- ing the atmosphere. Malaria, which means bad air, is the type of these so-called "miasmatic diseases." From this we may infer that fly screens and mosquito netting are more important in many sick-rooms than germicidal agents, as far as the dissemination of such infections through the air is concerned. In the cases where the infection is liable to contaminate the surrounding air, a thorough ventilation of the sick-room should be maintained. The infection disposed of in this way is generally lost by dilution, or killed by the sun. There is nothing equal to the open fireplace for the ventilation and purification of the air of the sick-room, for by this method the infection is not only carried away, but is destroyed by the heat of the fire in exit. Proper precautions must be taken at the bedside to pre- vent the infection leaving the body in a live and virulent form. These precautions differ for each class of infections and have been described under each disease in Chapter VI. The hanging of sheets wet with bichlorid of mercurj' or some disinfecting solution at the doorway serves a useful Digitized by Microsoft® DISINFECTION OF HOUSES, SHIPS, AND OBJECTS. 1 93 purpose in arresting some of the infection that may be float- ing in the air, and thus Hmiting its dispersion. It must, however, be remembered that sheets, while serving a useful purpose, are not an absolute guarantee, for they dry out very quickly and it is diflBcult to make the sheet close the opening so that there will be no air currents around the edges, especially if the doorway is used for persons passing in and out. When a room has been badly infected and the air of the room is suspected, it should always be given a preliminary fumigation with one of the gases, which will diminish the probability of the infection spreading through the air, and will protect the operators who have to take up the carpets, or prepare the bedding and the other contents of the room for steaming or other process. Ambulances. See Carriages. Bali,ast. See Vessels. Bandages, gauze, etc., may be sterilized Bandages, by boihng, steaming, or dry heat, in any Gauze, etc. of the apparatus described under these processes. Articles of this character should always Bed I/INEN, be disinfected after contact with any of Body I,.inen, the communicable diseases, for they are ETC. very apt to be infected. This may readily be done by boiling, by steaming, or by im- mersion in one of the ordinary germicidal solutions. Care must be taken in boiling or steaming woolen under- clothing, because of their liability to shrink. Digitized by Microsoft® 194 DISINFECTION AND DISINFECTANTS. Special care is necessary in washing and disinfecting towels, sheets, underwear, and the like that are soiled with discharges, such as pus, blood, or excreta. If such articles are heated or boiled without special precautions being first taken, they wiU become indelibly stained, by the coagulation of the albuminous matter which becomes fixed in the fiber. In Germany, wash that is soiled is treated by the follow- ing process : * It is wrapped in a sheet wet with subU- mate solution, and this placed in a sack likewise moistened with a germicidal Uquid. The sack is placed unopened in a solution containing 3 per cent, of soft soap and heated to 50° C. for three hours, and left in the same solution forty- eight hours after it cools. If not soiled with albuminous matter the wash is immersed in a solution of bichlorid of mercury i : 2000, with the addition of common salt. After this preliminary disinfection, the articles are boiled half an hour in a water containing : Petroleum, 10 gm. Soft soap, . . 250 gm. Water, 30 liters. A simpler method is to disinfect the fabrics containing the stains in a 5 per cent, solution of formalin for two hours and then remove and wash in the usual way. Wooden and iron beds may be effectively Bbds. disinfected by a mechanical cleansing with a hot disinfecting solution, such as bichlorid of mercury or carbolic acid. Care must be exercised not to overlook any of the joints or cracks, especially in wooden beds, which should be taken apart. *LeTy and Klemperer, " Klinische Bakter.," p. 434, Berlin, 1898. Digitized by Microsoft® DISINFECTION OF HOUSES, SHIPS, AND OBJECTS. 1 95 A careful search should be made for bedbugs, which niust be destroyed by use of the insecticide agents mentioned in Chapter IV. Mattresses and piUows are among the Bedding. most difficult objects to disinfect, on account of the deep penetration required. It is very important that they be thoroughly disinfected throughout their mass on account of the very intimate contact with the patient and the likelihood of their being deeply soiled with infected discharges. Therefore, nothing but steam should be trusted to render these objects safe. Bulbs. See Food. Good brushes can be boUed or steamed Brushes, without injury, and this is the best method of disinfecting them. If boiled in a solu- tion containing soap, soda, borax, or one of the alkalies, the brush may be more readily cleansed of the collection of oleaginous matter and epitheHal debris that collect about the bristles. Brushes made of poor bristles or with glued backs are injured by boiling. Such brushes must be mechanically cleansed in a soap or alkaline solution, and then soaked for an hour in corrosive sublimate i : looo, or carbolic acid 5 per cent. A 3 to 5 per cent, solution of formalin wUl also answer. Or the brush may be cleansed and disinfected at the same time by mechanical washing in a i per cent, solu- tion of tricresol or lysol. The ordinary exposure to for- maldehyd gas cannot be trusted to render a brush safe. It is well known how difficult it is to sterilize brushes for use in the operating room. It is the best surgical practice Digitized by Microsoft® 196 DISINFECTION AND DISINFECTANTS. to start with a new brush, which is thoroughly boiled each time and kept in one of the germicidal solutions. Brushes in hotels, public toilet rooms, railroad coaches, and other places, where they are used promiscuously by many persons, should be disinfected periodically to prevent them conveying ringworm and other skin infections. Brushes used by the barber should always be disinfected after using them on any customer having a diseased scalp, and they should be disinfected at the end of each day's work as a routine precaution. With the exception of their external sur- BooKS. faces, books cannot be disinfected in the bookcases or on the shelves of houses and libraries. However, if the books have not been handled or exposed to infection in any way except by their presence in the sick-room, there is no reason to consider any part of the book except the exposed surface infected. Such books may be rendered safe by exposing them to formaldehyd gas without first disturbing the books in any way. Books which have been handled by the patient, or which have been otherwise exposed to infection, require particular care in their disinfection, on account of the difficulty of pene- trating with any germicidal substance between the leaves. Books may be satisfactorily disinfected in a specially constructed chamber or in any small air-tight space, by means of formaldehyd gas. They must be arranged to stand as widely open as possible upon perforated wire trays. Under these conditions the exposure should be continued twelve hours in the special chamber, with high percentages of formaldehyd and a temperature of 80° C, a partial vacuum having first been produced. The binding, illustrations, and print of books are not injured by this process. See page 1 10. Digitized by Microsoft® DISINFECTION OF HOUSES, SHIPS, AND OBJECTS. 197 When only a few books are to be treated, in the absence of special apparatus they may be disinfected by dropping two or three drops of a 40 per cent, formalin solution on every second page, taking care to distribute the drops well. The book is then laid in a tight box or drawer in which more formalin has been sprinkled, and left in a warm place not less than twenty-four hours. Pamphlets and unbound volumes may be steamed with- out serious harm. Steam is not applicable to the disinfec- tion of bound books on account of the glue and leather. Dead bodies may be the source of spread- CadavBRS. ing many of the communicable diseases. The body, without previous washing, should be wrapped in a sheet wet with a strong germicidal solution, such as bichlorid of mercury i : 1000, carbolic acid 5 per cent., or tricresol i per cent., until it is disposed of. Should it be desirable to wash the body, it should be done with formalin or Labarraque's solution, or one of the solutions mentioned above. From a sanitary standpoint bodies dead of one of the communicable diseases are best disposed of by burning. When cremation is not practicable, the body should be sur- rounded by twice its weight of freshly burned lime in a tight coffin, and buried at least six feet underground. This treat- ment is effective in preventing the spread of cholera, typhoid fever, plague, smallpox, diphtheria, and most diseases to which man is liable. Embalming with the strong solutions of formalin and arsenic that are commonly used for this purpose is effective in destroying all but the surface infection of bodies dead of the communicable diseases. The disinfection of carcasses dead of anthrax is a very Digitized by Microsoft® 198 DISINFECTION AND DISINFECTANTS. important and difficult matter, and has been discussed in detail in the article on Anthrax in Chapter VI. Caps. See Hats. Cargo. See Vessels. Carriages, ambulances, wagons, cars, etc., Carriagks, ni^y be disinfected by having built a small Ambulances, tight structure in which they are inclosed Cars, etc. and then surrounded with formaldehyd gas. Such a building is used for the disinfection of ambulances in New York city. By using high percent- ages of formaldehyd such conveyances may be given a satis- factory surface disinfection in an hour. This method would be particularly applicable to street cars, and the railroad coach, cabs, and other public conveyances, where time is an important factor. Of course, if the vehicle has been used for the transporta- tion of a communicable disease, the cushions, lap robes, curtains, floor carpet, upholstery, and similar articles must be removed for steaming, immersion in one of the germicidal solutions, or for treatment according to the method given for its particular class, especially if the patient has soiled the interior of the coach with discharges. The treatment of vehicles does not differ in any way from the disinfection of rooms or other similar objects, and may be accomplished by a thorough drenching with a hose or a mechanical cleansing of the surface with any one of the ordinary germicidal solutions. See also Railroad Cars. Cisterns. See Wells. Digitized by Microsoft® DISINFECTION OF HOUSES, SHIPS, AND OBJECTS. 1 99 Clothing may be disinfected by a great Clothing. variety of methods. They may be boiled, steamed, soaked in disinfecting solutions, or exposed to dry heat or the action of gases. Of all the methods steam is the most reliable, but it has the disadvantage of shrinking some woolen goods, or creas- ing them and setting them out of shape. Good clothing and fine fabrics may be steamed without appreciable injury if they are exposed to steam under pressure, so managed that condensation and undue wetting are avoided, and pro- vided that the articles are hung or loosely laid in the steam chamber so that they do not come in contact with any metal parts, and finally, provided that, as soon as the steaming is completed, the articles are immediately removed and stretched and shaken in the air until they are cooled and dried. The combination of high percentages of formaldehyd gas with dry heat in a partial vacuum is a splendid method for the disinfection of clothing, fabrics, and baggage on a large scale. The method is rapid, has sufficient power to pene- trate heavy fabrics, and is not injurious. Clothing may be disinfected by formaldehyd gas in a room or inclosure by any of the methods given for the evolu- tion of that gas. Proper care must be taken to so arrange the clothing that the gas may have free access to all the surfaces, and the exposure should be not less than twenty- four hours to insure penetration. Formaldehyd gas by this method should not be trusted to disinfect quilted wraps or heavily lined overcoats and similar articles requiring deep penetration. Boiling and immersion, while very efficient, are limited to the disinfection of the simpler and cheaper articles of clothing. Digitized by Microsoft® 20O DISINFECTION AND DISINFECTANTS. Care must be taken not to injure colors Colors. in the process of disinfection. Many of the cheap prints run when wet, and such should not be disinfected by boiling, immersion in disinfecting solutions, or by steaming. In steam disinfection objects are sometimes soiled by being in contact with other articles dyed with soluble colors, and this possibility must always be guarded against in loading the chamber. (See page 74.) Sulphur dioxid is very ruinous in this respect. It bleaches practically all the vegetable and anilin dyes. It is very- apt to discolor white lead paint (oxid of lead), by the forma- tion of the black lead sulphid. It does not attack white zinc paint when dry. Formaldehyd gas has practically no effect upon colors. It can be used to disinfect an oil painting, water-color, or pastel. It does not affect the coloring matter of fabrics, excepting occasionally the delicate lavenders. Chlorin is a very active bleaching agent, and acts injuri- ously upon almost all the pigments commonly used in the arts. Chlorinated lime, the hypochlorites, and I^abarraque's solution likewise affect colors, on account of the chlorin liberated by their decomposition. Oxygen, ozone, and hydrogen peroxid are also very power- ful bleaching agents. Solutions of the mercury salts, of carbolic acid and the cresols, or formalin, have little special action upon pigments commonly used in the arts. Curtains. See Draperies. Carpets and rugs are very apt to become Carpets. infected with almost any of the communi- cable diseases, and they are troublesome to Digitized by Microsoft® DISINFECTION OF HOUSES, SHIPS, AND OBJECTS. 201 handle properly. In cases where they have become soiled with the infected discharges, or where gross carelessness has prevailed in the sick-room, they should be subjected to a preliminary exposure to one of the gaseous disinfectants, then carefully taken up, wrapped in a sheet wet with bi- chlorid of mercury, and removed for steaming. Stains due to organic matter, such as blood, sputum, and excreta, must be removed before the steaming, else they will become fixed. After the steaming they may be given a mechanical cleansing and hung up in the sunshine for several days. Carpets that have been exposed in the sick-room where proper precautions have been taken at the bedside to pre- vent the spreading of the contagium, may be safely treated without taking them up, although this is always preferable. The carpet may be disinfected in place by wetting it with a 5 per cent, solution of formalin, and keeping the room closed not less than twenty-four hours, or by exposing the carpet to the action of formaldehyd gas in full strength for twenty-four hours. Carpets that have become infected by the spilling of dis- charges, etc., should have the contaminated area immedi- ately saturated in a strong solution of formalin. Carpets in rooms that are being given a general disinfection with formaldehyd gas may be sprinkled or mopped with formalin just before the room is closed and the gas evolved. Cotton and cotton fabrics may be boiled. Cotton. steamed, subjected to dry heat at 150° C. for one hour, exposed to formaldehyd gas, or mmersed in any of the ordinary disinfecting solutions with- out appreciable injury. Sulphur dioxid not only bleaches the cotton, but rots the fiber, owing to the action of the sulphurous acid which is Digitized by Microsoft® 202 DISINFECTION AND DISINFECTANTS. formed by the gas in the presence of moisture and oxygen, and is therefore not applicable. Combs may readily be rendered safe by Combs. soaking in formalin, carbolic acid, or bi- chlorid solutions, after which they may be mechanically cleansed. The rubber and celluloid of which combs are now made will not, as a rule, stand boiling, steam- ing, or dry heat. As a rule these furnishings of a room do Drapijries ''lot come in contact with the patient or his Hangings, discharges, and therefore may be disinfected Curtains, by formaldehyd gas while the room itself is being treated. In case these articles are contaminated so that they need more than a surface disinfection, they should be steamed, in accordance with the plan laid down for the handling of carpets or immersed in one of the germicidal solutions. The sick-room should not contain draperies, hangings, or other unnecessary articles of this character, and it is always advisable to remove them, as well as the carpets before the possibility of contamination. Lime in one of its forms is best suited for Excreta. the disinfection of the excreta, in any quan- tity. For small amounts, formalin, carbolic acid, or one of its derivatives, as tricresol, lysol, saprol, is efficient. In hospitals the infected discharges are sometimes boiled in an appropriate vessel, with the addition of a deodorizing substance, as potassium permanganate. Whatever chemical substance is used, some of it should Digitized by Microsoft® DISINFECTION OF HOUSES, SHIPS, AND OBJECTS. 203 be placed in the vessel that is to receive the dejecta, and more is added afterward and the mass thoroughly mixed. Let the mixture stand a sufficient length of time,— not less than an hour, — depending upon the strength and nature of the disinfectant. In estimating the amount of disinfectant required for the disinfection of excreta in camps, quarantine stations, etc., count upon an average of 400 grams of solid excrement per person per day, and 1500 to 2000 c.c. of urine. Excreta must always be so protected that it will not be- come a breeding and feeding-place for flies and other insects, which are prolific ways of spreading cholera, t3'phoid fever, and perhaps other diseases. Milk of lime is a very cheap and efficient disinfectant for excreta. As officially prescribed for this purpose in the army of the United States, it is prepared by the addition of I per cent, by weight of the freshly slaked lime to 8 parts of water. In its application to fecal matter the milk of lime is em- ployed in the proportion of 5 per cent, by bulk, with a daily addition equal to 10 per cent, by bulk, of the estimated increment of feces. According to this method, to each 95 parts of feces there is added 0.62 part of water-slaked lime, or I part in 153. According to Munson, this seems a very small proportion for a substance of no very powerful germi- cidal properties, particularly in the absence of thorough mixing with the infectious material, or with the deteriora- tion of the lime through atmospheric influence, which is so liable to occur. In view of the cheapness of quicklime, and to avoid any possible failure in the attainment of disinfection, it will do no harm to err on the side of safety and considerably increase the strength or quantity of the milk of lime as prescribed above. IS Digitized by Microsoft® 204 DISINFECTION AND DISINFECTANTS. The perfunctory sprinkling of infectious matter with weak milk of lime, as is often done, is a procedure worse than useless. Lime has but slight effect upon odors and requires a long time to accomplish disinfection. lyime should not be thrown into the hoppers of water- closets, for the disinfection of the dejecta, without dilution, for otherwise the thick mass may accumulate and obstruct the pipes. In disinfecting the excreta with lime the reaction of the resulting mixture must be alkaline, else the object will not be attained (Phuhl). lyime, or the milk of lime, is ver\' useful for the disinfec- tion of privies, or trenches in camp, or in country practice. For its use under these circumstances the amount required may be arrived at as follows : The amount of fecal matter per person is reckoned at 400 grams a day. If the urine is also to be disinfected this may be counted as 1500 to 2000 c.c. per person daily. For the disinfection of the solid ex- crement alone, 5 grams of lime, or 40 c.c. of the milk of lime (i to 8), must be reckoned for each person per day. If the urine is included it will take four to five times as much. The mixture must have an alkaline reaction. Chlorinated lime is a powerful deodorant, vigorously at- tacking the gaseous effluvia of putrefaction, and is a useful disinfecting agent for excreta. A solution of good chlorin- ated lime in water in the strength of ^ to i per cent, by weight has been shown to disinfect typhoid and cholera stools in ten minutes, while a i per cent, solution will destroy anthrax bacilli in two hours. Thoroughly mixing the chlorinated lime with the fecal matter to be disinfected is essential. In the United States army a 4 per cent, strength of chlor- inated lime in solution is officially prescribed for use in the disinfection of the excreta of the sick, it being specifically Digitized by Microsoft® DISINFECTION OF HOUSES, SHIPS, AND OBJECTS. 205 stated that the chlorinated lime so used should be of good quality and not have undergone deterioration. Formalin ranks high among the list of germicidal agents useful for the disinfection of the dejecta! It penetrates deeply and is not hindered in its action by the albuminous matter present. Enough should be added so as to make 5 per cent, of the mass and be thoroughly incorporated. The vessel must be kept tightly closed at least an hour. As a deodorant it acts almost instantly. Carbolic acid in 5 per cent, solution added to a similar bulk of excreta cannot be depended upon to render the latter sterile in one hour. It can, however, be used for the disin- fection of infected stools, such as cholera, typhoid, etc., taking care to mix well and let stand at least one hour. Tricresol, lysol, and saprol are valuable agents for the disinfection of fecal matter in small amounts, on account of their energetic action, and because their efficiency is not impaired by the presence of albuminous matter. Sufficient quantities of these phenol derivatives must be added so as to be present in 2 per cent, of the entire mass, and thoroughly incorporated. Carbolic acid and its derivatives are more expensive than lime and without any special advantages. Ferrous sulphate is very extensively used for the disin- fection of excreta, but its germicidal powers are too weak to recommend it for this purpose. It is claimed also to have deodorant properties, which are denied by Foote. In using this salt of iron it is essential to add it to the fecal matter in solution in great excess on account of its feeble germicidal powers. If the contents of the latrine are semi-fluid it is best to add a concentrated solution. Munson recommends 5 parts of the iron salt to each hundred parts of the total contents of the latrine vault as essential to efficiency. In the French army ferrous sulphate is used in Digitized by Microsoft® 206 DISINFECTION AND DISINFECTANTS. lo per cent, solution, and it is officially laid down that at least 250 c.c. of such a solution should be used per day for each person using the latrine. Dry earth promotes the desiccation of excreta, thus pre- venting putrefactive changes while absorbing the odors. It has no inherent germicidal or antiseptic qualities, but is a useful means of disposing of dejecta in camps and country places when lime and chemicals are not at hand. A better method under these circumstances is to burn the dejecta upon an improvised fire. Corrosive sublimate is totally unfitted for the disinfection of excreta, because it coagulates the albuminous matter with which it combines, and therefore lacks penetration; nor does it destroy the bad odors. FbcES. See Excreta. The ordinary methods of cooking are, as Food. a rule, sufficient to render meats and vege- tables safe from the danger of conveying in- fection. The food must be well cooked throughout and must afterward be guarded against contamination by dust, by flies and other insects, by handling with infected hands, or by contact with infected dishes. The remnants of food or drink that have formed part of the patient's meal should be burned or boiled, — particularly if the case is one of diphtheria, tuberculosis, cholera, pneu- monia, plague pneumonia, or any of the exanthematous diseases in which the food is apt to become infected by hand- ling or by contact with the secretions of the mouth. In districts where cholera and typhoid fever or epidemic dysentery prevail, raw foods, such as salads, celery, toma- toes, and fruits, may be disinfected by half an hour's im- Digitized by Microsoft® DISINFECTION OF HOUSES, SHIPS, AND OBJECTS. 207 mersion in a 3 per cent, solution of tartaric acid and after- ward washed in boiled water. There is plenty of evidence now to prove that parasitic and infectious diseases may be spread through the con- sumption of uncooked vegetables, even where pestilential diseases do not prevail in epidemic form. G. Ceresole * found ameba, threadworms, eggs of tenia, oxyuris, anchy- lostomum, and a great variety of bacteria upon lettuce, endive, radishes, celery, and the like. Roots, bulbs, fruits, and other articles of food may be given an efficient surface disinfection by immersing them in a 5 per cent, solution of formalin. This is sometimes re- quired for food products of this nature coming from plague- or cholera-infected regions. This treatment does not harm the food value of these articles and is not poisonous. The floors should always be given careful Floors. attention because they are especially likely to be infected. The sputum of tuberculous cases, of pneumonia, diphtheria, etc., too frequently finds lodgment upon the floor. The plague bacillus has been found in the dust and dirt of the floor. The floor may best be disinfected by a soaking or by a mechanical cleansing with any one of the strong disinfecting solutions, such as bichlorid of mercury i : 1000, carbolic acid 5 per cent., tricresol i per cent., etc. Bichlorid of mercury should not be used for the disin- fection of the "dirt floors" frequently found in the Orient and also in the poorer hovels of our own country. Car- bolic acid, or one of its derivatives, is more trustworthy for this purpose, as its action is not hindered by the pres- ence of albuminous matter. *" II Policlinico," 1900-1901, p. 55. Digitized by Microsoft® 2o8 DISINFECTION AND DISINFECTANTS. Ordinary furniture, such as chairs, tables. Furniture, desks, bureaus, cabinets, sideboards, etc., made of wood, with hard pohshed surfaces, may be effectively disinfected with formaldehyd gas or sulphur dioxid, according to any of the methods given for evolving these gases. All the drawers and doors should be opened so as to expose all portions to the action of the gas. Furniture may also be disinfected by mechanical cleansing with any of the disinfecting solutions, taking care not to overlook any surface and to get the solution into all the cracks and crevices. Upholstered furniture is one of the bugbears of the dis- infector, on account of its bulk, its value, and the deep pene- tration sometimes required. If the upholstery is leather, oil-cloth, or other impervious material, it may be treated with one of the germicidal liquids, care being taken to get well into all the puckered tucks of the cushions. If the article is covered with a tapestry or other pervious fabric, the only efficient way of rendering it safe is by soaking the cushions through and through with a 5 per cent, solution of formalin and leaving the furniture in an inclosed space twenty-four hours. Fortunately, this treatment does no special injury to fine fabrics. Upholstered furniture which has simply stood in a house or room in which a case of infectious disease has occurred, and which has in no way come in contact with the patient or the infectious materials, may be considered as being in- fected merely upon the surface, and therefore may with per- fect safety be treated by gaseous disinfection. It is always well, in using formaldehyd, which is practically the only gas applicable for these objects, to sprinkle or wipe the surfaces of the upholstery with a 5 per cent, solution of formalin just before closing the room preparatory to liberating the gas.' Digitized by Microsoft® DISINFECTION OF HOUSES, SHIPS, AND OBJECTS. 209 Gauze. See Bandages. Glassware, porcelain, china dishes, and Glassware, the like may be disinfected by boiling, steaming, or immersion in any one of the disinfecting solutions. The hands should be thoroughly washed Hands. and disinfected after contact with infected material of any kind. It is very difficult to disinfect the skin, especially around the finger nails, so that a cursory immersion into a bichlorid solution will not suffice. After contact with the skin of a case of smallpox or one of the exanthematous diseases, or after contamina- tion with the discharges of cholera or typhoid fever, the hands should be immersed in a hot i : looo bichlorid solu- tion, then given a very thorough cleaning with soap and water, using a nail brush. After this the hands should be immersed in a i : looo bichlorid solution for three minutes. In surgical practice the following methods of disinfecting the hands are commonly employed: Filrbringer's method: The hands are actively scrubbed one minute with soap and water as hot as can be borne, then they are rubbed for a minute with 80 per cent, alcohol, and finally washed in a 0.5 per cent, sublimate solution. As modified and generally used this method consists of washing the hands in soap and hot water for five minutes, using the nail brush. They are then soaked in alcohol for one minute and scrubbed with a sterile brush. They are finally soaked in a I : 1000 bichlorid of mercury solution for three minutes. The method of Schatz, as modified by Kelley, is as follows : The hands are first vigorously washed with common brown kitchen soap or green soap and hot water for five minutes. Digitized by Microsoft® 210 DISINFECTION AND DISINFECTANTS. The hands thus mechanically cleaned and softened are next immersed in a hot saturated solution of potassium per- manganate until stained a deep mahogany color. They are then immersed at once in a hot saturated solution of oxalic acid, which decolorizes and completely sterilizes them. The oxalic acid is then removed by warm water or sterilized lime-water. Hangings. See Draperies. Hats and caps cannot be steamed because Hats and they usually contain sizing (glue) and Caps. leather. They may be carefully wiped with or immersed in one of the disinfecting solu- tions, preferably formalin, and then hung up to dry so that they will not lose their shape. Or they may be exposed for twenty-four hours to formaldehyd gas in sufficient concen- tration. Straw hats without trimmings may be exposed without injury to sulphur dioxid, as that gas is used in their manufacture to bleach them. Hides. See Leather. Holds op Vessels. See Vessels. The disinfection of houses resolves itself Houses. into the disinfection of its rooms {vide Rooms). As a rule it is better, in disinfect- ing an entire house with a gas, to treat each room or suite of rooms separately, and finally to fumigate the halls and stair wells. The disinfection of the entire house is rarely required. The infection of most diseases may be confined to the sick- Digitized by Microsoft® DISINFECTION OF HOUSES, SHIPS, AND OBJECTS. 211 chamber and the adjoining rooms; but if the patient has contaminated most of the rooms of the house before the nature of affection is recognized, or if, on account of careless- ness or other reasons, the infection is not confined, the entire house will need treatment. In this case it is best to begin with the upper stories and work downward, arranging so that all the rooms and halls of the house will be exposed to the disinfecting agent simultaneously ; where that is not possible, the upper stories of the house should be finished and locked so that they may not be used until the rest of the house is finished. Surgical instruments may be disinfected Instruments, by many methods, but they are best steril- SuROiCAi/. ized by the method of Schimmelbush ;* i. e., after careful cleaning they are boiled in a I per cent, solution of sodium bicarbonate for fifteen minutes or longer. This does not rust steel and does not dull the cutting edge. IvCather, hides, skins, and fur are ruined IvEATHER ^y boiling or steaming. They may be Hides, Skins, treated by immersion in one of the germi- FuR, ETC. cidal solutions. Leather which has not re- ceived a surface dressing is rendered hard and brittle by wetting, and should therefore be disinfected by one of the gases. Formalin "fixes" leather by combining with its albu- minous constituents, rendering it brittle, and should there- fore not be used for this substance. *"Arbeiten a. d. chir. Klinik d. k. Univ. Berlin," 5. Theil, 1891, S. 46 ei seq. 16 Digitized by Microsoft® 212 DISINFECTION AND DISINFECTANTS. IvETTBRS. See Mail. Flax or linen fabrics may be boiled, I/iNEN. steamed, or disinfected by immersion in any one of the ordinary chemical solutions used for this purpose. It may also be subjected to formaldehyd gas without appreciable harm. Sulphur dioxid rots linen fiber as it does cotton, and bleaches dyes, and should there- fore be avoided. Lithographs. See Pictures. First class letter mail has been accused Mail. of spreading smallpox, measles, scarlet fever, and diseases of the desquamating class. There is little danger of letters spreading the infec- tion of such diseases as plague, cholera, typhoid fever, tuber- culosis, and the great majority of the communicable dis- eases. However, the disinfector is often called upon to disinfect the mail as a matter of precaution. There are several methods by which the letter mail may be treated. One of the best ways for large quantities is to expose the letters to high percentages of formaldehyd gas, with dry heat in a partial vacuum (see page no). This method has the advantages of being quick and not requiring the puncturing or opening of the envelopes, it being sufficient to lay the letters loosely on end on the racks. The only special precaution necessary in this method is to eliminate the letters with wax seals, for this substance softens at the temperature of 80° C, which is the degree of heat necessary to obtain trustworthy results. The method presupposes the installation of expensive apparatus and the presence of a skilled attendant. Digitized by Microsoft® DISINFECTION OF HOUSES, SHIPS, AND OBJECTS. 213 A very simple method, which I practised with success in Havana upon large amounts ot letter mail, and which takes verjr little time, consists of the following procedure : One person clips the corner of the envelopes with a sharp scissors, and passes them on to the next person, who drops three or four drops of formalin into each letter, by means of an eye dropper. The envelopes are then placed in the sack, which has been liberally sprinkled with formalin, and more formalin is sprinkled between every few layers of letters as they are placed loosely in the sack. Use a fine spray, which will not wet the ink sufficiently to make it run. The sack is filled in successive layers and then tightly closed and laid in a warm place for no less than six hours — preferably overnight. Or it may proceed immediately on its journey, provided the sack is not opened until the proper time has elapsed. Very large quantities of mail matter may be disinfected in this manner in a surprisingly short time. This method is also particularly applicable to hospitals, lazarettos, quarantine stations, and similar places where only a few letters need treatment each day. In these cases the following procedure will be found useful and perfectly safe: The mail is collected every evening at a stated time, and each letter is treated inside and out with formalin as described above. The letters are placed in a tight box made especially for this purpose, and laid away overnight in a warm place. In the morning the box is carbolized upon the outside and taken to the picket line or quarantine limits, where the mail is taken out by the guard and, after a little preliminary airing, transferred to a clean receptacle and is ready for the post-office. Sacks of mail which have been treated by this method should not be opened in a closed room, for the smell of the formaldehyd is very unpleasant. This may be obviated by Digitized by Microsoft® 2 14 DISINFECTION AND DISINFECTANTS. opening the bags out of doors and letting them air half an hour, or by sprinkling some ammonia about. If the letters are exposed to formaldehyd gas evolved by one of the methods used for room disinfection they must be arranged so that all the surfaces of the envelopes are freely exposed to the action of the gas, and left twenty -four hours if the envelopes are not punctured, six to twelve hours if the envelopes are punctured. Sulphur dioxid cannot penetrate paper nearly so well as formaldehyd, and therefore it is necessary to puncture the envelopes if they are to be disinfected by this gas. In punc- turing envelopes for this purpose care must be exercised to use an instrument that will actually cut out a little circle of the paper, for if the letter is simply punctured with a sharp-pointed instrument the hole made seals itself from the interior of the envelope. In the absence of other means letters may be subjected to dry heat, either in special apparatus or in the kitchen Mattrbsses. See Bedding. Of all foods mUk is the most likely to be Milk. infected. It is a very good culture medium for almost all the pathogenic bacteria; for instance, fresh milk contaminated with a few typhoid, diph- theria, cholera, or plague bacilli will in a few hours at ordinary temperatures have every drop teeming with many of these organisms without appreciably altering the appearance of the milk. It is easy to understand how readily the infection of typhoid fever, cholera, diphtheria, or plague may get into the milk. The exanthematous diseases have frequently been traced to the milk-supply. The possibiUty of tuberculosis Digitized by Microsoft® DISINFECTION OF HOUSES, SHIPS, AND OBJECTS. 215 being conveyed in the milk is ever present. The milk-supply of a large city is always under suspicion, so frequently does it carry disease, and it is therefore fortunate that we have simple and sure methods of rendering it safe. Milk may best be disinfected by boiling or Pasteurization. Boiling coagulates the casein and renders the milk less palatable, and more difficult to digest for some persons, though it makes it absolutely safe so far as the destruction of infection is concerned. Pasteurization consists in heating the milk to a tempera- ture of from 70° to 75° C. (about i8o° F.) for half an hour and then chilling it quickly and keeping it cool until used. This degree of heat is sufficient to kill all the non-spore- bearing bacteria, such as tuberculosis, typhoid, cholera, dys- entery, diphtheria, and, in fact, practically all the infectious agents of the epidemic diseases to which man is liable. As the spores and some of the hardier saprophytes are not killed by this degree of heat, it is important to chill the milk quickly, for if allowed to cool slowly the continued warm tempera- ture favors the growth and multiplication of these forms of bacteria, which, although they do not cause disease directly, give rise to toxins or chemical poisons in the mUk which cause indigestion or very severe symptoms of poisoning. Money may convey the infection of the Money. communicable diseases, especially smallpox and the exanthemata. Metallic money may best be treated by immersion in a solution of carbolic acid 3 per cent., of formalin 3 to 5 per cent. Boiling water, steam, or dry heat is also applicable to the disinfection of specie. Paper money may be disinfected by sprinkling the notes with formalin, taking care to sprinkle the solution in small Digitized by Microsoft® 2l6 DISINFECTION AND DISINFECTANTS. drops and upon the face of each bill, then placing in a tight box in a warm place for six hours. The disinfection of currency does not differ from that of letter mail. (See page 212.) The stringed instruments may be dis- MusiCAi, infected by formaldehyd gas. The brass Instruments, wind instruments may be boiled, or, if they have keys, may preferably be disinfected by a careful washing with formalin or carbolic acid solution; or they may be subjected to formaldehyd gas. The wood- wind instruments and the mouth-pieces of the reed instru- ments may be treated with formaldehyd gas, or, better still, immersion in a strong formalin solution. The patient is, of course, the source of The Patient, almost all the infection with which we have to deal, and therefore the greatest care should be taken to prevent the contagion leaving the body in a live and virulent form. The methods of disinfecting the skin, the various dis- charges, the bedding, and other objects which come in con- tact with the patient have been enumerated under separate headings. In all cases of the communicable diseases scrupulous cleanliness of the patient, his bed and bedding must be exercised. The patient's skin may be bathed with one of the disinfecting agents in weak dilutions, and must always be kept clean with soap and water, or alcohol, depending upon circumstances. In the exanthemata the skin should be anointed with vaselin or a bland oil, to which a little carbolic acid may be added. This will largely prevent the contamination of the Digitized by Microsoft® DISINFECTION OF HOUSES, SHIPS, AND OBJECTS. 217 surroundings with the infection which leaves the body in the desquamating epiderm. In the case of cholera, typhoid fever, and the intestinal diseases, the buttocks must be kept clean and the napkins used for this purpose should be moistened with a solution of bichlorid of mercury or carbolic acid, and immediately after being used placed in a strong germicidal solution, boiled, or, better, burned. The sick-room should be kept freely ventilated, and the patient protected from the annoyance of flies and mosquitos. In the case of malaria, yellow fever, and other diseases con- veyed through the agency of insects, fly screens and mosquito bars must be used and the greatest care taken to destroy any insects that may gain entrance into the room. Special measures to prevent the spread of the infection from the patient are given under each one of the communi- cable diseases in Chapter VI, and need not be repeated here. Formaldehyd gas does not injuriously Pictures and affect photographs, lithographs, prints in Paintings, black and white or colors, oil paintings, water-colors, or pastels, and is practically the only method applicable to the disinfection of these articles. Pigments. See Colors. PiLivOws. See Bedding. Rags may be disinfected by any of the Rags. methods appUcable for fabrics; but as they are especially apt to be contaminated with the discharges and other infectious materials, they therefore Digitized by Microsoft® 2l8 DISINFECTION AND DISINFECTANTS. require treatment with methods which penetrate deeply— or better still, methods which sterilize, such as steam, boiling, or immersion in one of the stronger germicidal solutions. It is quite impossible to disinfect a bale of rags, prepared under great pressure for shipment. No disinfecting agent could penetrate such a firm mass. It is therefore necessary to unbale and expose all portions of the contents of the mass freely to the action of whatever disinfecting agent is used. At ports where large quantities of rags are shipped it is advisable to have a special car constructed, having racks upon which the rags are spread out for exposure to steam under pressure. The principles of disinfection as applied to Railroad railroad cars present nothing novel. The ap- Cars. plication of these principles varies somewhat with the kind of car we have to deal with. Flat cars, or open cars, seldom need disinfection, for even should they become infected the constant exposure to the sun and weather is usually sufficient to render them safe from the danger of conveying disease. They may readily be disinfected, whenever that may be necessary, by scrubbing or flushing them with carbolic acid, or bichlorid of mercury solutions. Freight cars, or box cars, seldom need disinfection. In the case of the insect-borne diseases, the destruction of the mosquitos and flies which such cars are very apt to harbor is necessary. Freight cars are best treated for this purpose by fumigation with sulphur dioxid, which at the same time destroys bacterial infection upon the surface. The outside of the car rarely needs any attention. If the freight car is infected with any of the exanthemata or diphtheria, cholera, or other bacterial infections it may Digitized by Microsoft® DISINFECTION OF HOUSES, SHIPS, AND OBJECTS. 219 be disinfected with formaldehyd gas, or, better still, by washing or flushing with one of the usual germicidal solu- tions, and then left open to air and dry, preferably in the sunshine. In actual practice it will sometimes be found useful to disinfect these cars by steam from the locomotive. Cattle cars and cars used to transport live stock need special attention, particularly if anthrax, tetanus, glanders, or tuberculosis is the disease with which they are contami- nated. The disinfection of cars of this type is so much like the disinfection of a stable that it is unnecessary to repeat the process here. (See page 229.) Day coaches and parlor cars: The disinfection of the ordinary passenger coach presents no special difficulty. The day coach is nothing more nor less than a room on wheels, and all the principles for the treatment of rooms apply with equal force to these cars. If the disinfection is done as a precautionary measure (which should be required at stated intervals), it is sufficient to follow a thorough mechanical cleansing, with formaldehyd gas. The carpets and rugs and all similar articles, including the upholstered seats and back rests, if removable, should be taken from the car and given a mechanical cleansing in the open and exposed to the sunshine. The spittoons and the floors of the car are especially liable to become infected; the floors may be mopped or scrubbed with one of the germicidal solutions, and the contents of the spittoons may be disposed of in one of the ways mentioned under the heading Sputum. The cuspidors themselves should be steamed or well rinsed in a carbolic acid bath. If the disinfection is done on account of the known con- tamination with one of the communicable diseases, it is treated exactly as a room would be under like conditions. The railroad coach is very likely to harbor mosquitos. Digitized by Microsoft® 220 DISINFECTION AND DISINFECTANTS. flies, and other insect pests that may carry disease. For this reason precautions will have to be taken, on cars leaving districts infected with yellow fever, malaria, plague, etc., to keep these insects off the cars ; or measures will have to be taken to destroy them after they get on board. As both of these requirements are difficult, if not impossible, to carry out with certainty, it will be found best to have relays, and to change cars upon leaving an infected for a non-infected but infectible area. Sleeping cars- present a greater danger than any other rolling stock. The berths are very apt to become infected with tuberculosis, diphtheria, and any one of the exanthe- mata, especially as they are kept closed — almost hermeti- cally sealed — against the fresh air and sunshine during the day. Much of the difficulty encountered in the disinfection of the sleeping car is due to peculiarities in construction, such as the compact manner in which the bedding is stowed away, the heavy and unnecessary carpets and hangings, the ex- cessive molding and ornamentation which catch the dust and hold the infection, the use of such materials as plush for the upholstery, the vile arrangement of the open-hopper water-closet, the absence of faucets arranged so as to wash in running water instead of a bowl used also for the teeth cleaning and other processes, the absence of any system of ventilation, and the like. A sleeping car is nothing more nor less than a bedroom on wheels, and all the methods de- scribed for the treatment of such rooms (see page 222) are applicable. Before attempting to disinfect the interior of a sleeping or other passenger coach with a gas, it is important to close the deck sashes and all the ventilator openings for the Pintsch gas flames. Much gas will be lost through the open hopper of the water-closet unless that is tamponed. Some Digitized by Microsoft® DISINFECTION OF HOUSES, SHIPS, AND OBJECTS. 22 1 cars have a system of ventilating ducts, the fresh air entering under the seat, or somewhere near the bottom of the car, which must all be carefully sealed against leakage. Formaldehyd gas is practically the only one of the gaseous disinfectants which may be used for the treatment of the sleeping car. As this gas lacks the power of penetration, all the berths must be opened and all the bedding and other fabrics should be removed for steaming or other treatment, as it is practically impossible to arrange all the bedding and fabrics in the small space of a car so that every surface will be freely exposed to the full effects of the gas. After the removal from the car of the bedding, hangings, carpets, and other fabrics, the toilet room should be given special attention The drinking glasses, the bowls and slabs of the wash-stands, the brushes and combs, the seat of the water-closet, and other objects should be washed or im- mersed in one of the germicidal solutions suitable to each class. A 3 to 5 per cent, solution of formalin, or a 5 per cent, solution of carbolic acid, or a i per cent, solution of tricresol or lysol is especially applicable to this disinfection. Bichlorid cannot be used on account of its corrosive action, especially upon the metal parts. After all this preliminary treatment the car may then be subjected to the formaldehyd gas, care having been exer- cised that all the openings are well sealed, as described above. It may well be understood that the method for the routine disinfection of the sleeping car, while presenting no particular difficulties, do not satisfy the requirements of modern activities. Railroad managers demand germicides which are instantaneous in their action, non-destructive in their effects, all-pervading in their power of penetration, so that no disarrangement of the contents of the car would be neces- sary, and so that the disinfection could be accomplished Digitized by Microsoft® 222 DISINFECTION AND DISINFECTANTS. without loss of time and with little cost. Further, the dis- infecting agent used must leave no unpleasant odor or other disagreeable effects to offend the sensitiveness of the pas- sengers. Such ideal methods are not known. It takes time and money to effectively eradicate the infection from so complicated a structure as a sleeping car, and when the traveling public are more thoroughly informed upon the dangers that menace them, they will require a very thorough purification of the sleeping coach periodically as a necessary precautionary measure. The disinfection of the living room calls Rooms. for all the resources of the disinfector's art. The fact that it is necessary to bring the apparatus and materials to the room in order to disinfect it with most of its contents is one of the main difficulties and will call forth the ingenuity as well as the vigilance of the operator. A room cannot be effectively disinfected while it is occu- pied. Any gaseous substance in sufficient concentration to destroy bacteria would make life unbearable. Under these circumstances the best that can be done is to wash all exposed surfaces with one of the germicidal solutions, and to observe the strictest cleanliness about the patient, the bed and bed- ding, and to promptly disinfect and dispose of the discharges, etc. It is absurd to keep a pan of carbolic acid, formalin, chlorinated lime, or any other substance under the sick-bed or in the water-closet with the hope that it will in any way purify the air and prevent the spread of the disease. Occa- sionally a deodorant about the room may be used with advantage, but where proper cleanliness and ventilation are observed, such substances are rarely called for. It is, of course, of prime importance to prevent the infec- Digitized by Microsoft® DISINFECTION OF HOUSES, SHIPS, AND OBJECTS. 223 tion of the room, by taking the precautions required for the particular disease in question, but we are now dealing with the destruction of infection and not its prevention. The method to be employed for the disinfection of a room will vary somewhat with the disease for which the disinfec- tion is done. As a rule one of the gases is to be preferred for the group of exanthemata, because the infected particles are apt to fly about and lodge in places inaccessible to the other methods. In the case of malaria, yellow fever, and filariasis the destruction of the mosquitos must be given our first consideration. In disinfecting rooms for plague our efforts must be directed against the rats, mice, and fleas, as well as to the destruction of the plague bacillus. For cholera and typhoid fever we must pay particular attention to the water and food. In routine work in the treatment of rooms liable to be infected with a variety of diseases, and disinfected as a precautionary matter, formaldehyd gas is the most generally useful agent we possess. Certain articles commonly found in living rooms., such as bedding, carpets, rugs, cuspidors, upholstered furniture, and other articles deeply infected or difficult of disinfection, must be treated separately as described for each article. In case the room is so constructed that it is impracticable to disinfect it with a gas, it must be treated in accordance with the methods given seriatim for its walls, floors, and all its contents. Preparation of a Room for Gaseous Disinfection. — After closing the doors and windows, paste strips of paper over the cracks and crevices, or calk them with towels, waste, and the like. (See illustration, page 85.) Be particular to close the hot-air register, and to properly close all venti- lators, fireplaces, and other openings. Open closets and small doors, and expose all the drawers, lockers, and similar Digitized by Microsoft® 224 DISINFECTION AND DISINFECTANTS. places, so that the gas may have free access to remote corners. Furniture should be moved away from the walls, so that there may be a free exposure of surfaces. Curtains and hangings should hang loosely, so that nothing may keep the gas from gaining free access to every portion of the fabrics. Clothing, bedding, and articles of this character should be suspended on lines in a clear portion of the room, and not too far from the place where the gas is evolved, in order that they may have the full benefit of the undiluted effects of the disinfecting agent at a point where the gas is more concentrated and where the more energetic currents favor penetration. In thus arranging a room it is very important to expose to the gas the same surfaces that were exposed to the infec- tion. It may therefore be mistaken zeal to disturb the contents of the room too much ; besides, the too vigorous shaking up of the dust or infectious matter may be the means of spreading the disease. Ordinarily, carpets and rugs should be left in place, and after the fumigation they may be taken up and hung in the sun for a day or two, and pounded or otherwise mechanically cleaned. If the carpets and rugs have been infected with the discharges or badly contaminated in other ways, the particular spots should be thoroughly saturated with a strong solution of formalin or other strong disinfectant. Then, after the preliminary fumigation, the rugs and carpets should be removed for steaming and sunning. Bedding, towels, and other articles of like nature may be left to the action of the gas, afterward removed for boiling or steaming, or immersion in one of the disinfecting solutions. Whenever articles are removed from the room for disinfection they must be wrapped in a sheet wet with one of the germicidal solutions. Bichlorid of mercury is particularly appropriate Digitized by Microsoft® DISINFECTION OF HOUSES, SHIPS, AND OBJECTS. 225 for this purpose. The gases cannot be depended upon to exert their disinfecting influence very deeply; therefore any article which there is reason to believe is deeply or badly infected should be removed for other treatment, depending upon its character. Rubbish that may be gathered up in the room should be burned. The cuspidors and their con- tents require special treatment, and any other article which the gases cannot be depended upon to disinfect thoroughly must be removed and disinfected according to its nature. After the room has been properly prepared, all is made tight and the room filled with the gas according to the methods given, and it should then be sealed in such a way that it cannot be opened without the knowledge of the dis- infector. After the proper time has elapsed the room should be opened by the disinfector himself, and the operation should not be considered successful unless there is a distinct smell of the gas present. The windows and doors are then opened so that the gas may be allowed to blow away, or neutralized according to the methods given. A room which has been carefully treated as above outlined may be considered disinfected and will need no other treat- ment to render it safe. However, it is always advisable to follow the disinfecting processes with a very thorough mechanical cleansing and a good sunning and airing. When a room is to be disinfected by another method than one of the gaseous disinfectants, a somewhat different pro- cedure is followed. Article after article is removed piece- meal and disinfected by appropriate methods. After the room is emptied, the walls and other surfaces are flushed with bichlorid of mercury i : looo or one of the other germi- cidal solutions in equivalent strength. Roots. See Food. Digitized by Microsoft® 2 26 DISINFECTION AND DISINFECTANTS. Rubber is injured by dry heat. Pure Rubber. rubber may be boiled or subjected to steam under pressure without injury. Articles made of impure rubber, such as mackintoshes, rubber shoes and boots, rubber sheeting, vulcanized rubber articles, and the like, are ruined by boiling or steaming, and must be dis- infected by immersion in one of the germicidal solutions. Rubber nipples of nursing bottles, after mechanical cleans- ing, should be boiled in an alkaline solution, containing a little borax or baking soda, and then washed in boiled water. Rugs. See Carpets. Ships. See Vessels. Silk seldom needs disinfection, and for- vSiLKS. tunately so, for it is difficult to treat without injuring the fabric or color. Formaldehyd gas does not injure the fiber and has no effect upon the great majority of colors ; but the delicate lavenders of anilin origin are sometimes slightly modified in tint, after ex- posure to this gas. While steam does not harm the silk fiber appreciably, it ruins the fabric, so that this method of disinfection is totally inapplicable. vSkin. See Hands. Skins. See I^eather. The sputum, not alone of the sick, but of Sputum. the well also, is often laden with the infec- tion of disease, especially pneumonia, pul- Digitized by Microsoft® DISINFECTION OF HOUSES, SHIPS, AND OBJECTS. 227 monary tuberculosis, diphtheria, plague, and other affections of the air passages. Infection is spread by means of the sputum, especially when it dries and is disseminated by the air currents. An- other fruitful method of spreading diseases, the infection of which is found in the sputum, is by the act of kissing; also by using spoons, forks, cups, etc., which have been in the mouth of the sick or those whose sputum is infected, and shortly afterward used without being disinfected. There is stUl another way in which the sputum contaminates the air and the surface of objects — viz., in coughing, sneezing, speaking, and other acts of an explosive expiratory character the sputum is sprayed into the air often to a considerable distance, even a couple of yards from the mouth, and the air currents will carry the minute droplets to all parts of a room. The sputum should be kept well covered until it is dis- posed of. Simply keeping water in the bedside cups or in the cuspidors wiU prevent the danger of the dissemination of infection through the agency of dried sputum, though an antiseptic solution is to be preferred for this purpose. The best way to disinfect sputum is by heat. A small quantity may be placed directly upon the fire and burned up; the same method is also most suitable for the handker- chiefs and other articles that have been used to hold the expectoration. Next to burning, boiling or steaming is the safest method of treating infected sputum. The boiling may be accom- plished in any appropriate vessel, and the steaming may be done in either streaming steam or in the autoclave under pressure. In hospitals and in private houses this method is recommended, care being taken not to heat the ordinary glass or glazed earthenware cuspidors too suddenly for fear of breaking them. 17 Digitized by Microsoft® 228 DISINFECTION AND DISINFECTANTS. The disinfection of sputum is difficult to accomplish with the chemical solutions, on account of its dense consistency and tenacious character, which hinder penetration. Bi- chlorid of mercurj' solutions are entirely inapplicable to the disinfection of this material. The bichlorid coagulates the albuminous matter of the sputum and thereby prevents penetration, and by uniting with the albuminous substances Fig. 53- ■ . JO- .... .- Autoclave for Disinfecting Sputum. it is used up and rendered inert so far as its disinfecting powers are concerned. Carbolic acid in 5 per cent, solution may be used for the disinfection of sputum, but it cannot be considered trust- worthy because it coagulates the albuminoid matter, though not so energetically as bichlorid of mercury. Tricresol or lysol in 2 per cent, solutions is well suited for this purpose, or formalin in 3 to 5 per cent, solution, these substances to Digitized by Microsoft® DISINFECTION OF HOUSES, SHIPS, AND OBJECTS. 229 be used in generous amounts and to be well incorporated and to remain in contact with the infected sputum no less than one hour. A very good apparatus for the disinfection and disposal of the sputum of hospitals, sanatoria, etc., consists of an auto- clave in which the material is steamed under pressure and at a temperature of 120° C. The steam is admitted through the pipe S, Fig. 53, and after the completion of the process the disinfected mass is washed through the drain D into the sewer by water entering the autoclave at W. The disinfection of a stable requires a very Stabiles. thorough application of all the resources at the hand of the disinfector. The conditions met with in a stable render its disinfection doubly hard, not only on account of the accumulation of organic filth, which has worked into the many crevices and saturated the woodwork, but on account of the high resistance of the an- thrax and tetanus spores, for which stables are sometimes disinfected. In addition to these diseases, stables require disinfection on account of tuberculosis, glanders, pleuro- pneumonia, and various diseases of man as well as those of the domestic animals. It is advisable to give the stable a preliminary fumigation, preferably with sulphur, in order to destroy surface infec- tion and the vermin which always infest these places. The preliminary disinfection is especially important in the case of plague, glanders, tuberculosis, or any of the exanthem- atous diseases, not only to prevent the spread of the infec- tion, but as a safeguard for the disinfectors. Then remove all small articles that need disinfection. The blankets should be wrapped in moist bichlorid sheets and boiled, steamed, or burned. Buckets, curry-combs, brushes, stall tools, and Digitized by Microsoft® 2 3° DISINFECTION AND DISINFECTANTS. other equipment that has been in contact with the sick animals or with infectious materials, should be mechanically cleaned with hot carbolic solution, in which they may be allowed to soak over night. Metallic and wooden objects or utensils should be given a thorough preliminary cleansing with a stiff brush and hot water and soap, and then boiled or immersed in a 5 per cent, solution of carbolic acid or 2 per cent, solution of tricresol for several hours. lyeather articles, as harness or equipment, should receive a similar preliminary cleansing and be scrubbed with either a strong solution of bichlorid of mercury or carbolic acid. All hay and grain should be removed from the racks and mangers, and all bedding from the floors. After its careful collection at some designated point this refuse should be saturated with petroleum and destroyed by fire. The stable must now be soaked with a strong antiseptic solution applied with a hose, or splashed on all surfaces by means of mops. The floors, corners, and stalls must be saturated with the solution. On account of the presence of so much albuminous matter, phenol or one of its derivatives is preferred for this purpose to sublimate solutions. Now scrape out the ddbris from all the cracks in the floors and walls; collect it for burning. Then clean the woodwork with hot lye or a strong alkaline soap solution, and follow with another general hosing with the antiseptic liquid. After several days' exposure to air and sunshine the interior of the stable should receive a fresh coat of whitewash, ap- plied thickly, and prepared from lime freshly burned shortly before the time of use. The watering troughs are very apt to be infected, espe- cially in dealing with glanders. In all instances, not only the troughs and watering buckets should be disinfected, but the water remaining in them, for often there is no drain Digitized by Microsoft® DISINFECTION OF HOUSES, SHIPS, AND OBJECTS. 23 1 or sewer, and this water poured on the ground may be a source of subsequent infection. The water may first be disinfected by the addition of a suitable amount of any of the ordinary soluble germicides. The troughs are then to be mechanically cleaned, thoroughly removing all organic matter, and then applying a strong germicidal solution to both the inside and the outside. For metal-lined troughs the use of bichlorid of mercury is, of course, inapplicable, and for such carbolic acid, tricresol, formalin, or potassium permanganate is recommended. Most antiseptics are poi- sonous and must, therefore, be finally washed out of the trough or buckets by flushing with fresh water and then airing in the sunlight before they are again used. Strong carbolic solution or formalin should be poured down all pipes and drains. Sometimes the ground in the immediate vicinity of the stable wUl need some attention ; lime will generally be found most useful for this purpose. Carcasses and excreta are to be disinfected and disposed of according to the methods given under these titles. Great care must be exercised in disinfect- Tabi^eware. ing knives, forks, spoons, and dishes used by patients suffering from communicable diseases. Cholera, typhoid, tuberculosis, pneumonia, diph- theria, plague, and the exanthemata may be conveyed by inattention to this precaution. Tableware is most readily- disinfected by scalding. It is seldom necessary to burn tents after TenTagE. exposure to any infectious disease, for they may be effectively disinfected by any of the following methods : Digitized by Microsoft® 232 DISINFECTION AND DISINFECTANTS. The tent is emptied of all its movable contents, each ob- ject being disinfected in accordance with methods appro- priate for it. The canvas is then thoroughly wetted from the inside with a 5 per cent, solution of formalin or carbolic acid or a I : 1000 solution of corrosive sublimate. The solu- tion may be applied with mops, brooms, or with a hand pump. The lower portion of the canvas walls, together with the sod-cloth, and the tent poles and flooring, should receive a particularly thorough wetting. Ordinarily the sunshine is a sufficient disinfectant for the outside of the tent. Another method, more difficult of application, but more thorough than the preceding, is to strike the tent; lay the canvas flat on the ground and scrub or saturate it with the hot disinfecting solutions mentioned above, preferably for- malin, which does not rot the canvas. Rinse well with clear water and allow to dry in the sunshine. Tents that can be tightly closed may be disinfected by a gas. In this case it is necessary to tise a large excess of the gas and a longer exposure on account of the inevitable waste. Sulphur dioxid will rot the fibers of the canvas ; formaldehyd is therefore pref- erable. The tent, its poles, and floor should be exposed to the sunlight for several days and thoroughly dried before again being used. It is generally preferable to pitch the tent on fresh, uninfected ground. If that is not practicable, the space should be given a good sunning and may be liber- ally sprinkled with lime before the tent floor is again laid, or if the ground has been contaminated with discharges, it may be saturated with a germicidal solution. The urine is generally disinfected with Urink. the dejecta (see Excreta). It should always be disinfected in the case of cholera, typhoid Digitized by Microsoft® DISINFECTION OF HOUSES, SHIPS, AND OBJECTS. 233 fever, and most of the communicable diseases, by adding suffi- cient carbolic acid to make a 5 per cent, solution, of bi- chlorid of mercury to make a i : 1000 solution, or formalin sufficient to be present in the proportion of 3 to 5 per cent. The disinfection of a vessel does not differ Vessels. materially from the disinfection of houses and rooms. It should not, however, be attempted by one not familiar with the intricacies of ma- rine architecture, for many special conditions are met with on board ship that are very different from those found on shore. While the principles of disinfection as applied to vessels present nothing unusual, the application of these principles calls for much ingenuity and the keenest vigilance upon the part of the disinfector. It is important to enlist the sympathies of those on board with the necessity for the disinfection, for the successful accomplishment of the purification of the vessel may be ma- terially helped by the cheerful cooperation of the passengers and crew, otherwise the difficulties of the problem are greatly magnified. Formerly a distinction was made between the methods of disinfecting a wooden and an iron vessel. This arose from the fact that almost all wooden vessels have some rotten and spongy wood, especially about the fore-foot and bilge; there are also many more cracks and open joints about a wooden ship than a metal one, which afford lodg- ment for organic matter and infection. In addition to all this, a wooden hull is always damper than an iron hull, for almost all wooden vessels leak more or less. The micro-organisms are apt to be deeply lodged in the moist dirt and organic matter of the many crevices. A wooden vessel, therefore. Digitized by Microsoft® 234 DISINFECTION AND DISINFECTANTS. as a rule, requires a very thorough mechanical cleansing and a longer exposure to the germicidal agents to insure penetration and disinfection. While the general method of treating vessels is the same for most of the bacterial infections, special measures are called for with each disease. For example, with cholera particular attention must be paid to the water; for plague the destruction of the rats and other vermin is of prime importance; for yellow fever and malaria efforts must be directed against the mosquito; for smallpox and the ex- anthematous diseases the usual surface disinfection of the living apartments, the clothing, bedding, and the like, is required. A vessel is rarely so badly infected that it needs a disin- fection throughout. Just what portions of the vessel and its contents require treatment is often a very difficult prob- lem to solve. There is no more reason to fumigate the hold of a vessel because a case of smallpox appeared in the cabin or steerage, than there would be to disinfect the basement and sub-basement of a tenement house because a case had appeared in one of the upper stories of the building. WTien an infectious disease breaks out on board a vessel, the in- fection may be confined to one or two compartments or a limited area quite as successfully as may be done in build- ings on shore. "In case of doubt, disinfect" is not a bad rule for the quarantine officer to follow in his practical deal- ings with ships, for, after all, the measures which we take must from the nature of the case be greatly in excess of the absolute requirements. A great deal may be learned by a very thorough inspec- tion of the vessel. To be sure, we cannot see the germs with our unaided vision, but we can see the dirt and moisture and other conditions which favor their life and virulence. Digitized by Microsoft® DISINFECTION OF HOUSES, SHIPS, AND OBJECTS. 235 It is, therefore, the duty of the quarantine officer, or whoever has charge of the disinfection of the vessel, to re- quire a very thorough mechanical cleansing of all its parts which in his judgment require it. This matter is dwelt upon with emphasis in the purification of vessels, because filth is a condition too frequently met with on the sea, and one of great importance to communities and nations. The in- troduction of an exotic pestilence is a very serious matter to a community, and it is just such infections that are spread from land to land by vessels. The disinfection of a large vessel cannot effectively be done without all the modern contrivances of a well-equipped quarantine station. A rowboat, a launch, or small sailing craft may be disinfected with a tub of bichlorid solution, but good work cannot be accomplished on larger vessels by the use of makeshifts. Before the disinfection of a vessel is commenced it should be, brought alongside the pier or barge containing the neces- sary appliances. All the passengers are then to be taken off, and aU the crew, only excepting the few who are neces- sary for the safety of the vessel and those who are to help in the disinfection. The quartermasters, the boatswains, and the carpenter are very useful hands to aid in the process, on account of their practical knowledge of the individual pecu- liarities in the construction of the vessel and their intelligence in carrying out directions with faithfulness. When the personnel have left the vessel, all their effects are removed and disinfected in accordance with the methods outlined for objects of that class. The baggage, bedding, and other objects, no matter what their character, after disinfection should not be returned on board until the vessel itself is finished. This injunction applies, of course, equally well to persons. No one should 18 Digitized by Microsoft® 236 DISINFECTION AND DISINFECTANTS. be allowed on the vessel except those actually engaged in the work, who as far as practicable should be immune, and should wear suitable garments. All the bedding, bed clothing, hangings, floor runners, and other fabrics must now be removed to the steam cham- bers for disinfection. Especial care must be taken to obtain all the used and soiled linen, which is usually kept in special compartments called the "dirty linen lockers," and are under the care of one of the stewards. For some reason the stewards who have this material, which is so apt to be infected, in their care, dislike to disclose its presence to the quarantine officer. After all the objects needing disinfection by a special pro- cess have been removed, attention is then directed to the vessel itself. The various compartments of the vessel may be disinfected by any of the methods described under room disinfection. A favorite way of disinfecting the forecastle, the steerage compartments, quarters for petty officers and similar apart- ments, is by flushing them with a bichlorid solution. This may be applied with a force pump, by mops and buckets, or by tricing up a tub of solution sufficiently high to give a good pressure. In applying the disinfecting solution with a hose, begin at one end of the deck ceiling and systemati- cally flood every inch of surface, coming down the walls and finally the floor. Apartments that are very dirty will need a mechanical cleansing either with a lye solution and stiff brush, or with a carbolic or sublimate solution, depending on circumstances. The cabins, saloons, and similar apartments usually con- tain metal and bright work, which are ruined by bichlorid or sulphur. They must, therefore, either be given a for- Digitized by Microsoft® DISINFECTION OF HOUSES, SHIPS, AND OBJECTS. 237 raaldehyd fumigation or a washing down with a 5 per cent. carboHc acid solution. In disinfecting large vessels it is well to start forward with the forecastle and work aft systematically, first on the starboard and then the port side, taking care to require every door to be unlocked, and trusting only to a personal inspection concerning its contents and uses. There are cer- tain places, Hke the lamp room, the paint locker, the sail locker, the chain locker, the carpenter shop, the chart room, and pilot house, the engine and boiler rooms, all the machinery, and the like, that are rarely infected and, as a rule, need no treatment. Special care must usually be directed to the sick bay and any apartment in which a patient was cared for, and all the living apartments, espe- cially the steerage. The water-closets on board ship should be thoroughly cleansed and flushed with water and disinfected with milk of lime or any of the disinfecting solutions. They may be hosed with the bichlorid solution while that is being applied. In sailing vessels of the older type the forepeak needs similar treatment. The Hold. — About the best way to disinfect the holds of vessels is by sulphur fumigation or by a solution of corrosive sublimate applied with a hose. It is often desirable to use both methods, in which case the sulphur should always pre- cede the hosing in wooden vessels, because the water may seal many of the cracks and thus prevent the gas penetrating. In the hold, attention must be given to the bilges. They may be flushed with carbolic or formalin solutions and then pumped out. Care must be taken in using bichlorid solution for fear of injuring the pump. Before applying sulphur dioxid to the hold of a wooden vessel open all the limbers and air streaks, so that the gas Digitized by Microsoft® 238 DISINFECTION AND DISINFECTANTS. may penetrate between the skin and the hull. If the sulphur is burned in iron pots, set them in a pan of water, which will guard against lire and by evaporation give the requisite amount of moisture necessary for the germicidal action of the gas. Place the pots in an elevated position, either on piles of ballast or on the 'tween decks, because the sulphur fumes first rise, afterward fall, and if the pots are near the bottom, the fire may go out for want of oxygen. In leading sulphur fumes into the hold from a sulphur furnace by means of a system of conduits and pipes, it is considered best to lead the pipes down the hatch well toward the bottom of the hold, so that the apartment may fill up with the fumes from the bottom, displacing the air above. For this reason open- ings above for the escape of the air must be provided. This is best managed by leaving open one or two of the ventilators, or part of the hatch, and after the gas has begun to escape in some quantity to close up tight. In disinfecting a ship it is verj'^ easy to calculate the amount of sulphur to be burned from her tonnage. A register ton is 100 cubic feet. Count half a pound for each ton, which will make the necessary 5 pounds per 1000 cubic feet. The gross tonnage of a vessel indicates her actual cubic capacity. The net tonnage gives the capacity of her cargo- carrying space. The difference between the two wUl give the capacity of the spaces devoted to the engines and ma- chinery, living apartments, and storerooms, etc. In sailing vessels and in freighters the net tonnage may be taken as the cubic capacity of the hold. In freight vessels 40 cubic feet of merchandise is considered a ton, provided the bulk does not weigh more than 2000 pounds. This ton used as a commercial unit for freight charges must not be confused with the registered tonnage based upon the measurement of the vessel. Digitized by Microsoft® DISINFECTION OF HOUSES, SHIPS, AND OBJECT'S. 239 The holds of vessels infected with yellow fever should always be given a preliminary fumigation with sulphur before they are inspected, in order to kill the mosquitos and thereby protect the quarantine officer and his employees from infection. The empty hold of an iron steamer may be disinfected by steam, provided the hold is above the water line. The compartments of such vessels often have steam pipes for use in case of fire. The same system may be utilized for the disinfection of the compartment or for the disinfection of clothing and other fabrics by streaming steam. The water tanks and casks of vessels are very apt to carry infection. The water itself may be infected with cholera, typhoid, dysentery, or other water-borne infections; or the water may contain mosquito larvae, which may play serious havoc in case of yellow fever or malaria. It is, therefore, necessary in the first case to disinfect the water by adding formalin (i per cent.) or carbolic acid (3 per cent.) and let it stand several hours before disposing of it. Sometimes the water may be boiled in situ by leading a steam hose into the tank. In the case of mosquito larvae it will be necessary to use petroleum or one of the other insecticides. If the harbor is on salt water the water containing the larvae may be spilled with safety into the water, as neither the anopheles nor the stegomyia wUl develop in salt water. Cargo. — As a rule the cargo of a vessel infected with a pestilential disease need not be disinfected. There is no reason to consider the cargo of a vessel that has had a case of cholera, or smallpox, or typhus fever, or the like, on board, as having been contaminated, because, as a rule, the cargo hatches are kept well battened down during the voyage and there is little or no communication with the infection. Individual articles of the cargo, such as rags, household Digitized by Microsoft® 24° DISINFECTION AND DISINFECTANTS. goods, second-hand articles, or food products, from infected localities may need treatment. New articles of merchan- dise or new manufactured goods seldom carry infection. There is one exception to this, in the case of a vessel in- fected with plague. In such a ship the rats carry the infec- tion deep down among the cargo and in and about the bilges. It is very important not only to destroy the rats, but also to dispose of their dead bodies without allowing the infec- tion to spread. This can best be done by a process of frac- tional disinfection, wliich is done as follows : After a preliminary sulphuring overnight, some of the cargo is placed upon a Hghter, carefully examining every piece, as it is strapped preparatory to hoisting out of the hold, for dead or live rats. Bales of cotton, feathers, and rags, and similar articles must be inspected for nests. The unloading should only be done during daylight. At night- fall the hatches are again battened down and the fumigation is repeated. The process is continued by alternately un- loading by day and fumigating by night until the hold is empty. The cargo upon the lighter should be freely ex- posed to the sun for one or two days before it is taken to the dock. It needs no other disinfection. This is a rather expensive and tedious process, but there is no other way known by which the cargo may be removed from a plague-ridden vessel without allowing the infection to escape. The dead rats found upon a plague ship should not be handled while the bodies are still warm for fear of the fleas which may carry the infection. In any event it is well to first saturate the bodies of the rats and a consid- erable surrounding area with a strong disinfecting solu- tion or insecticidal gas, when they may be taken up with tongs or with the hands protected by gloves or towels wrung out in a disinfecting solution. Digitized by Microsoft® DISINFECTION OF HOUSES, SHIPS, AND OBJECTS. 24I Ballast. — Vessels bring two kinds of ballast: 1. Water. 2. Solids. Water ballast is particularly dangerous when it has been obtained from a river, fresh- water lake, or other body where cholera, typhoid fever, or dysentery prevails. It is a rule in quarantine practice to require vessels in fresh-water ballast from cholera-infected districts to return to the open sea, where the ballast tanks are pumped out and refilled with salt water. Some one should be sent along to see that the pro- cess is properly carried out. It is not always expedient to send a vessel to sea, but whether the water ballast is pumped into the river or harbor or at sea, there should first be introduced into each tank, if practicable, a sufficient quantity of formalin or carbolic acid to make a strong germicidal solution, and this should be left several hours before it is pumped out. Ballast Consisting of Solids. — Vessels bring the greatest variety of substances as ballast. The kind which is most apt to carry infection is called sand by the captain, but an inspection of this "sand" will discover the fact that it con- sists largely of the street sweepings and rubbish from the port from which the vessel hails. Such ballast should under no circumstances be unloaded on the city front, especially if it comes from an infected district. Ballast which con- sists of clean, hard rock, or sand from the beach is not apt to carry infection of any kind and usually needs no atten- tion from the quarantine officer. It is difficult to dispose of ballast, because most vessels, particularly sailing craft, depend upon this weight for their upright position. Almost all harbors have rules forbidding the dumping of ballast and other materials in the harbor; it is, therefore, necessary to have what is known as a ballast Digitized by Microsoft® ^42 DISINFECTION AND DISINFECTANTS. wharf to successfully handle this perplexing problem. The ballast is removed from a portion of the hull, which is then disinfected and refilled with a sufficient quantity of new ballast from an unquestionable source. This is repeated until all the old ballast has been removed. In case a vessel arrives with such ballast at a port where there is no ballast wharf, the ballast may be placed upon lighters, which are dumped at sea, or the vessel may be given enough additional ballast to enable her to go to sea in order to jettison her in- fected ballast. In the latter case care must, of course, be taken to trim the two kinds of ballast so that they will not come in contact. Wagons. See Carriages; also Railroad Cars. The walls and ceiling of a room are as a Walls. rule infected only superficially, and may be effectively disinfected by one of the gase- ous processes. Such surfaces may also be disinfected by washing down with bichlorid or carbolic solutions, prefer- ably hot and applied by means of a hose or any other method that will thoroughly wet the surface. The solution is al- lowed to remain until it dries and is followed by a mechanical cleaning. When practicable, it is better to scrub or mop the wall with the hot disinfecting solution, by means of brushes, cloths, etc. The spraying of walls and other surfaces with a very fine spray of corrosive sublimate solution or any other material that is not volatile at the ordinary temperatures is a very faulty method, for the entire surface is not wetted and portions thus escape disinfection. In applying a solu- tion with a hose it is always advisable to begin with one corner of the ceiling, and systematically wet every portion of the ceiling, walls, and floor from above downward. This Digitized by Microsoft® DISINFECTION OF HOUSES, SHIPS, AND OBJECTS. 243 method is particularly applicable to the holds and com- partments of vessels, to freight cars, outhouses, cellars, water-closets, wooden buildings, and other rough structures. A very effective method of disinfecting^ the walls and other surfaces of a room is to spray them liberally with a strong formalin solution with a Behm's sprinkler (see page iis), or to wet the entire surface with a weaker solution (5 per cent.). The operation must be done quickly and the room immediately tightly closed and kept so at least twelve hours. Outhouses, water-closets, cellars, and similar rough sur- faces, after a preliminary disinfection or cleansing, may with advantage be coated with whitewash ma-da from freshly slaked lime, which in itself is a good disinfectant. In Germany the method of rubbing the walls with fresh bread has been proposed, but it is tedious, expensive, and not reliable. Water is one of the principal means of Water. spreading the intestinal diseases, such as cholera, typhoid, dysentery, and the like. Small amounts intended for drinking and culinary purposes may be rendered safe by filtration or by boiling. The addi- tion of chemicals is not generally advisable. Water may be filtered through kaolin (Pasteur-Chamberland), or similar filter of fine diatomaceous earth (Berkfeld), so that it is sterile and entirely harmless so far as its power of convejdng disease is concerned. Filters, however, should not be de- pended upon in a household, for the reason that they are untrustworthy, and thereby give a sense of false security. The best filter will only work bacteriologically pure a week or two, when the microbes grow through the pores of the filter. Further, while filters are theoretically perfect, they often have imperfections in construction, such as imperfect Digitized by Microsoft® 244 DISINFECTION AND DISINFECTANTS. joints, or pinholes, or cracks. Such filters deliver a clear, sparkling-looking water, in which, however, lurk the same germs found in the raw water. For household use the best method of treating an infected or suspected water is first to filter it with any process that will clarif)' the water and then to boil it. It should be thor- oughly boiled for ten or fifteen minutes. Many people ob- ject to boiled water because is tastes flat. This is owing to the dissolved air being driven out by the boiling, which may be obviated by shaking or by agitation with an egg beater, or by other mechanical means so that the air may again become dissolved, which gives the water life and makes it palatable. It is a mistake to boil water first and then filter it. The opposite should always be done. The filtering is too un- certain and should not be depended upon for more than taking out the coarser particles in suspension. Water that is infected or suspected of being infected with cholera, typhoid fever, or other pathogenic micro-organisms on board a ship, or in casks or cisterns must be disinfected before it is disposed of. This may be done by adding forma- lin 3 to 5 per cent., allowing it to remain several hours. On board ship the water can sometimes be boiled in situ by leading a steam hose right into the tank. The water used for bathing the patient Water, is often contaminated, especially by cases Bathing. of typhoid fever, cholera, the exanthemata, etc. Such water should be disinfected be- fore being allowed to flow away. This may be done cheaply by adding milk of lime in the proportion of i : 50 ; or carbolic acid suflicient to make a 3 per cent, solution and allowing it to stand an hour. Formalin is useful for this purpose and Digitized by Microsoft® DISINFECTION OF HOUSES, SHIPS, AND OBJECTS. 245 should be added so that the 40 per cent, formalin solution is present in the water in the proportion of 3 to 5 per cent. Bichlorid of mercury should not be used in metal tubs or where the water flows through lead pipes or soldered joints. Water Tanks. See Vessels. The water pipes become infected either Water Pipes, from the water that flows through them or from breaks, leaky joints, etc. The entire system of a city may be involved, or the short lead of a local supply. After the source of the trouble has been corrected, the pipes must be disinfected before the water coming from them can be considered safe. For this purpose it is desir- able to use something that is not poisonous. Formalin or milk of lime is best suited, though carbolic acid has been used. Bichlorid of mercury is too poisonous to be considered in this coimection and, besides, it must not be used where there is lead piping. In Nietleben, Koch disinfected the entire system of the town by introducing a 3 per cent, solution of carbolic acid into the pumps, and allowing it to flow into all portions of the pipes, where it remained twenty-four hours. The car- bolic acid was then washed out with water. This has the disadvantage that the water will taste of the carbolic acid for a long time. Milk of lime is effective, but has the disadvantage of tend- ing to obstruct the pipes. Formalin is expensive, but is preferable for this purpose on account of its high efficiency, its quickness, and its non-poisonous character. Formalin is particularly applicable to the disinfection of the water pipes of wells, cisterns, and small supplies of this char- acter. Digitized by Microsoft® 246 DISINFECTION AND DISINFECTANTS. The ojdy trastworthy way of rendering the Wells and water from an infected well or cistern safe Cisterns, is to boil the water before using it, and to correct the evil at its source. It is not necessary to emphasize the fact that, where possible, all sus- picious water-supplies should be avoided ; but circumstances may arise by which a well or cistern, the only readily avail- able source of water-supply for an isolated camp, quaran- tine station, farm-house or ship, may be infected and seri- ously inconvenience the users of the water, unless some safe remedy is at hand. It is practicable to disinfect wells and cisterns provided the contamination is not continuous or repeated. The method to be used varies, depending upon whether the scarcity of water necessitates the use of the infected water itself or whether a new supply may be at hand. If the infected water must be used it should be boiled. No other method of purifying it, such as filtering or adding potassium permanganate, etc., should be tnisted. If the well or cistern may be disinfected with its contents and the water then discharged, one of the following procedures will be safe: The best disinfectant for this purpose is formalin, on account of its high efficiency and its non-poisonous nature. Enough of the strong (40 per cent.) formalin should be added so that it wiU be present in the proportion of at least i per cent. After standing several hours the well or cistern should be thoroughly washed with the solution, not overlooking the walls of the well, which must be given a very thorough mechanical scrubbing with a stiff broom and plenty of the disinfecting solution. All parts of the pump, if there is one, and the piping must be purified with the solution. The disinfection of wells may also be accomplished by Digitized by Microsoft® DISINFECTION OF HOUSES, SHIPS, AND OBJECTS. 247 the use of freshly burned Hme. About half a barrel of lime is thrown into the well, stirred up with the water, and the walls are scrubbed down with the resulting milk of lime. The well is then pumped out, cleaned, allowed to refill, and a second supply of lime added ; after which the well is allowed to stand for twenty -four hours. After a thorough stirring the solution is then pumped out and the well is allowed to refill and is re-emptied until the water is practically free from lime. Wells and cisterns may also be disinfected with carbolic acid, or any of the cresols, or potassium permanganate, but no chemical is as quick and safe for this purpose as formalin. The raw wool may be steamed, boiled. Wool. or immersed in one of the disinfecting solu- tions. The objection to using boiling water or steam upon woolen fabrics is due to their tendency to shrink. The better grades of woolen cloth are "sponged" — that is, steamed — before being made into garments, and such articles may be disinfected by steam, provided that care is taken to prevent them being pressed or pulled out of shape in the process, and provided that care is exercised to place them in the steam chamber so that they will not be in contact with any of the metal parts, and also provided that as soon as the process is over the articles are stretched and shaken in the air while still steaming hot. Woolen articles that are injured by steam or hot water may be disinfected without injury by formalin or formal- dehyd gas, according to the methods already given for the application of these substances . In the disinfection of woolen goods with formaldehyd gas it is important to use an excess of the gas and a long exposure, — preferably twenty-four hours, — for the reason that the organic matter of the woolen Digitized by Microsoft® 248 DISINFECTION AND DISINFECTANTS. fiber absorbs large volumes of formaldehyd, which not only consumes appreciable quantities, but hinders penetration. The combination of formaldehyd with dry heat, as described on page no, is particularly suitable for the disinfection of woolens, without injuring them in any way. Digitized by Microsoft® CHAPTER VI. DISINFECTION FOR THE COMMUNICABLE DISEASES. TYPHOID FEVER. Typhoid, or enteric fever, is a widespread communicable disease, frequently occurring in severe epidemics. The symptoms of the disease are very inconstant. A typical case is marked by a continued fever lasting about four weeks, a rose-colored ^eruption, diarrhea, abdominal tenderness, tympanites, and enlargement of the spleen. The period of incuba.tion is variously stated from eight to fourteen days, sometimes twenty-three. The cause of typhoid fever is a short, actively motile rod, called the Bacillus typhosis, sometimes the Eberth bacillus, in honor of its discoverer, who described the organism in 1880. The bacillus of typhoid fever does not have spores. The organism is taken into the mouth, passes into the intestinal canal, where under favorable conditions it grows and multiplies, invading the system, giving rise to the lesions and the symptoms of the disease. A catarrhal condition exists throughout the small and large intestines, and the lymph follicles become swollen, hyperplastic, and may ulcerate. The bacillus is readily found in the inflamed lymphoid tissue, also in the rose-colored eruption, the en- larged spleen, and mesenteric glands. The bacillus fre- 249 Digitized by Microsoft® 2 5° DISINFECTION AND DISINB'ECTANTS. quently invades the blood, and may be found widely dis- seminated throughout the organs and tissues of the body. The typhoid bacillus produces a soluble poison in the course of its growth, called typho -toxin. It is this poison which is largely responsible for the fever, the inflammation of the lymphoid elements of the body, the effect upon the heart and nerves, and the more serious features of the disease. The bacillus of typhoid fever is eliminated from the body in the stools, the urine, and sometimes in the sputum, so that practically all the discharges from the body may con- tain the infective agent and must be disinfected in order to prevent the spread of the disease. The discharges from the patient contaminate the water, the milk, and the food-supply. It is largely in this way that the disease is spread from the sick to the sound. Ty- phoid fever may be communicated through the medium of articles of diet other than the water and the milk. For instance, green vegetables, such as salads, radishes, celery, and the like, that are eaten without previous cooking, may be contaminated with infected water or soil that has been fertilized with the human manure. Raw oysters have also been known to set up several small epidemics of the disease. There is little evidence to show that typhoid fever is air- borne, or that the infection is, as a rule, taken into the system in any other way than by the mouth. This is a very im- portant fact in applying our disinfecting agents for the sup- pression of the infection. It is true that pulmonary forms of the disease without intestinal lesions have been reported, but such instances seem to be exceptional. Flies are responsible for much of the spread of typhoid fever. They breed in and feed upon the dejecta and the infected discharges, thereby conveying the infection di- Digitized by Microsoft® Fig. 54. Tvi'HcjILl P.ACII.I.I, I'UKE Cui/JUli F,G. 55. 'I'yPHOID CuLONY OX Gelaiin. Digitized by Microsoft® Digitized by Microsoft® DISINFECTION FOR THE COMMUNICABLE DISEASES. 253 rectly to the food-supply. It is easy to understand how flies, and other insects with similar habits, carry the typhoid bacUli smeared upon their feet and bodies, as well as in their intestinal contents, thereby contaminating the meat, the butter, and other foods, especially the milk, in which this organism grows so well. A can of milk contaminated with a few typhoid bacilH may, in a few hours, at ordinary tem- perature, be teeming with the infection, without producing Fig. s6. Typhoid Bacillus with Flagella. any apparent change in the milk. Flies, by alighting upon our lips or other portions of our body, may be the means of introducing the infection more directly into our mouths. The importance which flies play in spreading the infection of typhoid fever is not realized. This factor must always be taken into account in applying our disinfectants and other means to hmit the spread of the infection. The typhoid bacillus is a hardy organism. It is found in the water, the soil, the air, the dust, sewage and in the 19 Digitized by Microsoft® 254 DISINFECTION AND DISINFECTANTS. milk, as well as upon soiled clothing, etc., contaminated directly or indirectly by the discharges of the sick. It finds abundant conditions in nature for its growth and develop- ment and enjoys the power of accommodating itself more readily to environment than the majority of the pathogenic bacteria. For instance, the addition of from o.i to 0.2 per cent, of carbolic acid to the culture media does not retard its growth and development. It may retain its vitality for Fig. 57. Typhoid Bacilli Invading the Submucous (TJ.) and the Muscular (M.) Coats of the Intestines. — [Baumgarten.) three months in distilled water, which indicates what a minute amount of organic matter is necessary for the life of the typhoid bacillus. A moist temperature of 60° C. will kill the bacillus of typhoid fever in ten minutes, and boiling water or steam at a temperature of 100° C. will destroy the vitality of the bacillus at once. It usually dies quickly when dried, al- though it has been kept alive several months on fabrics. Digitized by Microsoft® DISINFECTION FOR THE COMMUNICABLE DISEASES. 255 It is apparently not affected by freezing. It soon dies when exposed to the bright, direct rays of the sun. Formaldehyd and sulphur dioxid kill this bacillus in the strengths and times stated for the employment of these gases. All the ordinary germicidal solutions in the strengths given for the destruction of non-spore-bearing bacteria are efficient disinfectants for the typhoid bacillus ; for example, bichlorid of mercury i : looo, carbolic acid 3 to 5 per cent., formalin 3 to 5 per cent., tricresol i per cent., etc. The disinfection for typhoid fever begins with the destruc- tion of the infection in the discharges as they leave the body, before they have a chance to contaminate the surroundings, the water or food-supply. The evacuations from the bowels should be received in a vessel containing a 5 per cent, solution of carbolic acid, 2 per cent; tricresol, or 5 per cent, formalin. More of the solution must be added afterward so that it is present in equal volume and thoroughly incorporated throughout the mass. The mixture should stand one hour before it is dis- posed of. Bichlorid of mercury is not suitable for the de- struction of the infection in the dejecta on account of its property of coagulating and combining with the albuminous matter, which prevents its penetration. Time and its various compounds are cheap and efficient disinfectants for this purpose and the methods for their use are given on page 202. The urine frequently contains the infective agent of the disease and is usually disinfected with the evacuations from the bowel. If passed separately it may be disinfected by adding sufficient bichlorid of mercury to make a i : 1000 solution, or carbolic acid 3 to 5 per cent., tricresol i per cent., or formalin 3 to 5 per cent., and allowed to stand one hour before it is discarded. Digitized by Microsoft® 256 DISINFKCTION AND DISINFECTANTS. The sputum will also need treatment as it frequently con- tains the typhoid bacillus. The proper methods of disinfect- ing the sputum have been given upon page 226, and need not be repeated here. All materials that have become contaminated with the discharges from a case of typhoid fever must be disinfected by appropriate methods. This applies especially to the towels, bedding, and other fabrics used about the case. As boiling water or steam destroys the vitality of the typhoid bacillus instantly, either of these methods is particularly applicable to the disinfection of objects of this class. If the bedding is not soiled it may be immediately boiled, otherwise it must be treated so as to take out the albuminous materials in order to prevent indelible staining, resulting from the coagulation and fixing of these materials in the fabric. The bedding and fabrics contaminated with the infection of typhoid fever may also be disinfected by immersion in one of the germicidal solutions mentioned above. The bedding should be changed frequently and every- thing about the sick-room kept clean and fresh. The room should be well ventilated and the floor and surfaces kept clean and free from infection by frequent mopping with a I : 1000 bichlorid solution. The patient himself will need scrupulous attention and careful nursing in order to keep his skin clean. The mouth and lips need frequent washing with listerine, boracic acid, or other mild antiseptic solu- tions. The buttocks must be cleansed and washed with a I : 1000 bichlorid solution, and the rags used for this pur- pose had best be burned. The food may be disinfected by thorough cooking and the milk by boiling or Pasteurization, which consists in heating the milk to a temperature of 70° C. for half an hour and then chilling it suddenly. After the food and milk have been Digitized by Microsoft® DISINFECTION FOR THE COMMUNICABLE DISEASES. 257 disinfected it is important to guard against their recon- tatnination, by contact with infected water or by flies. The spoons, cups, and other tableware should be scalded before being used again, and the remnants of food remaining Fig. 58. • A Stick Culture of the Typhoid Bacillus in Gelatin. from the patient's meal should be burned or boUed before being thrown out. The hands of the nurse and others who come in contact with the patient or his discharges must be very carefully disinfected by immersing them in one of the germicidal solutions (see page 209). This procedure is important from Digitized by Microsoft® 258 DISINFECTION AND DISINFECTANTS. a general standpoint of preventing the spread of the disease, but is doubly important on the farm or dairy, where the same hands that nurse the sick or handle the dejecta after- ward milk the cows. The sick-room should be carefully screened to prevent the annoyance as well as the danger of flies. Any insects found in the room should be caught and burned. In cases where the above precautions have been intel- ligently carried out there is no reason to fear the spread of the infection, and it is not necessary to practise a general disinfection with one of the gases. In fact, both formal- dehyd gas and sulphur dioxid are of little practical use in combating an infection that is taken into the body through the alimentary canal and not the respiratory system. In other words, it is more important to boil the drinking water, and to thoroughly cook the food, and to Pasteurize the milk, and to protect against the infection carried by flies, than to attempt to destroy with one of the gases the typhoid bacilli that may contaminate the surfaces of exposed ob- jects. CHOLERA. Cholera is a communicable disease native to India, where it is always present, sometimes existing in widespread and very fatal epidemics. From time to time it is transported along the lines of travel and commerce to all parts of the world. Many severe epidemics have been caused in seaport towns by the introduction of a few cases on a vessel. Cholera is often called Asiatic cholera on account of its home in India, and to distinguish it from cholera nostras, cholera morbus, and other forms of non-communicable affections with choleraic symptoms. Digitized by Microsoft® Fig. 59. ' i Si'iRii.LU.M OF Cholera. Fig, 60. Involution Forms of thk Slirillum of Ciioi.eka. — (Van Eniiengeiii.') Digitized by Microsoft® Digitized by Microsoft® DISINFECTION FOR THE COMMUNICABLE DISEASES. 261 A typical case of cholera is characterized by violent purg- ing, cramps, rice-water discharges, and rapid collapse. The period of incubation varies from a few hours to five days. The disease is due to the "comma bacillus" discovered by Koch in 1 883-1 884. This micro-organism is curved or spiral-shaped and is therefore now called the Spirillum cholera asiaticcs. It is actively motile, and grows very well on alkaline media containing the slightest trace of albu- minous matter, at ordinary temperatures as well as at the temperature of the body. The spirillum of cholera does not have spores. In the body the infection is confined to the alimentary tract. The cholera spirillum is practically always intro- duced into the system in the drinking water or with the food. It may also be introduced into the mouth by means of the hands or other objects that have become soiled with the infection. Of aU the diseases of man that occur in epi- demic form cholera is the type of the water-borne infections. There can no longer be any doubt but that the great out- breaks of this disease in large communities are always due to the contamination of the drinking water. The spirUlum of cholera grows well in milk, and will keep alive and viru- lent a long time in moist albuminous food-stuffs, so that articles of food may spread the infection as well as the water. Vegetables and fruits are apt to become infected with the polluted water or from other sources, and if eaten raw may cause the disease. The flies play a similar rdle in spreading the infection of cholera that they do in typhoid fever. After the cholera spirillum passes the acid juices of the stomach, it grows and multiplies in such enormous numbers in the intestines that every drop of the mucous discharges Digitized by Microsoft® 262 DISINFECTION AND DISINFECTANTS. from the intestines may contain myriads of the organisms. During the course of its growth and multiphcation it pro- duces a poison or toxin which gives rise to the diarrhea, vomiting, cramps, and prostration which characterize the disease. The spirillum of cholera remains confined to the intestinal canal. It does not invade the blood, and is there- fore only eliminated from the body in the matters passed from the bowels, and sometimes in the vomit. The cholera spirillum is somewhat less resistant to ex- ternal influences than the typhoid bacillus, and the same agents used for the destruction of the typhoid bacillus may be used for the destruction of the infection of cholera. Fig. 61. Colonies of the Spirillum of Cholera after Twenty-four, For- ty-eight AND Seventy-two Hours' Growth on Gelatin Plates . — ( Curtis.) A moist heat of 65° C. will kill the spirillum of cholera in five minutes. Boiling water or steam at 100° C. kills the infection almost instantly. Most authorities agree that it dies quickly when dried, usually in from three to four hours. In a moist condition it retains its vitaUty for months, especially in the presence of organic matter, but it soon loses its virulence. The sunlight is also quickly fatal. The organism may live a long time in water, as may well be imagined from the fact that the disease is water-borne. In fact, it has been shown that if planted in sterilized water Digitized by Microsoft® DISINFECTION FOR THE COMMUNICABLE DISEASES. 263 this organism grows with great rapidity and can be found aUve after months have passed. Formaldehyd and sulphur dioxid kill the spirillum in the strengths and times stated for the employment of these gases. All the ordinary germicidal solutions used in the strengths given for the destruction of non-spore-bearing bacteria are Fig. 62. Spirillum of Cholera Growing in Gelatin, Showing Liquefaction. efficient disinfectants for the cholera spirillum. For ex- ample, bichlorid of mercury i : 1000, carbolic acid 3 to 5 per cent., tricresol i per cent., formalin 3 to 5 per cent., etc. The disinfection of cholera begins at the bedside. In general the measures and methods described to prevent the 20 Digitized by Microsoft® 264 DISINFECTION AND DISINFECTANTS. dissemination of the infection of typhoid fever are appH- cable for cholera, and need not be repeated in detail. Most important is the destruction of the infection in the stools and in the vomited matter. For this purpose use formalin 5 per cent., carbolic acid 5 per cent., tricresol 2 per cent., or lime, and thoroughly incorporate the disin- fectant throughout the mass and allow it to remain covered one hour. The above substances are considered the most trustworthy for the disinfection of these materials in small amounts, but in their absence other germicides mentioned in the article on excreta (page 202) may be used. Bichlorid of mercury is not applicable for this purpose on account of its lack of penetration in the presence of albuminous matter. All the bedding, body linen, towels, and other fabrics that have in any way come in contact with the patient, or his discharges should be immediately boiled, steamed, or im- mersed in one of the disinfecting solutions. The hands of the nurse and the body of the patient must also be kept clean and free from infection by frequent use of one of the disinfectants applicable to this particular purpose. The excreta and aU objects that have become contami- nated must be disinfected at once, or, if this is not possible, they must be carefully protected from the flies and other insects. When cholera prevails or is present in epidemic form, it is essential to boil all the drinking water and thoroughly cook all the food. More than this, it is important not to eat or drink out of cups or plates that have been washed with the infected water. All the tableware must be scalded, the milk boiled or Pasteurized, and no green vegetables, such as salad, radishes, celery, and the like, partaken of, unless first treated with tartaric acid and washed as de- scribed on page 207. Digitized by Microsoft® DISINFECTION FOR THE COMMUNICABLE DISEASES. 265 There is no need to practise disinfection with one of the gases after a case of cholera where the above precautions have been carried out. If through ignorance or neglect the infection has contaminated the room and its contents, a general disinfection may be done with formaldehyd gas or sulphur dioxid according to the methods described for apply- ing these agents for non-spore-bearing infections. So well do we know the habitat of the cholera spirillum in nature, as well as its channels of introduction into and dis- charge from the body, that we can apply our germicidal agents with great accuracy and with every assurance of destrojdng the infection and limiting the spread of the dis- ease; in fact, our methods have reached such a satisfactory state that it is possible to live in the midst of a raging cholera epidemic without contracting the disease. DYSENTERY. Dysentery is a communicable disease, occurring in wide- spread epidemics with great fatality, especially in the tropics and warm climates. The disease is characterized by an in- flammation of the lower bowel, accompanied with frequent and painful stools, often bloody. The symptoms of dysentery may result from one of many different irritating poisons, but the communicable dysentery with which this article deals is a specific disease, due to a definite living entity, the Bacillus dysentericE, described by Shiga in 1 899. It is a short, actively motile rod, closely resembling the bacillus of typhoid fever. The bacillus of dysentery does not have spores. It is believed that dysentery is transmitted in very much the same way that typhoid fever is. The cause of the disease is taken into the intestinal tract usually with the drinking water. The milk and food may also convey the infection. As the poison is excreted from the body in the evacuations Digitized by Microsoft® 266 DISINFECTION AND DISINFECTANTS. from the bowels it is reasonable to suppose that the flies and other insects may play a part in disseminating the infection. The vitality of the bacillus of dysentery is precisely similar to that of typhoid fever, and the principles of disinfection are the same as for that disease, so that it is not necessary to repeat them here. Another form of communicable dysentery prevalent in Fig. 63. Amceba dysenterIjE. — (After Roos.) Ameba without any foreign contents, b. Ameba containing blood-cor- puscles, c. Ameba with large vacuoles, d. Young forms, c En- cysted forms. tropical and warm climates is believed to be due to a pro- tozoon — the Amceba dysenterice. This form of the disease is usually chronic, and, so far as known, the same methods of prevention and disinfection are applicable to it as to the above. DIPHTHERIA. Diphtheria is a communicable disease, sometimes occur- ring in severe epidemics among the children. Diphtheria is characterized by an inflammation of the mucous membranes, especially of the throat. The character of this inflammation varies very much in degree. It may resemble the simple catarrhal inflammation resulting from Digitized by Microsoft® DISINFECTION FOR THE COMMUNICABLE DISEASES. 267 "catching cold," or when more severe may cause a fibrinous deposit or false membrane, by which the disease has long been recognized clinically. Every degree of severity is met with, from the mildest type to the malignant variety that results fatally in few hours. Diphtheria is not confined to the throat, but may attack any of the mucous membranes of the body, including the conjunctiva. The disease may also complicate wounds, and open sores may be the seat of a typical attack of diph- theria, accompanied with a false membrane and all the constitutional manifestations of the disease. The period of incubation is "from two to seven days, oftenest two." The cause of diphtheria is a bacillus bearing the same name — Bacillus diphtheria, first seen by Klebs under the microscope in 1883 and isolated in pure culture the next year by Loeffler, who proved this organism to be the cause of the disease. It is therefore often spoken of as the Klebs- I/Oeffler bacillus. The bacillus of diphtheria is a non-motile rod of variable length and very irregular in shape. It is often swollen on one end, presenting a club-shaped appearance, or it may be pointed or wedge-shaped. It stains in an irregular manner with the basic anilin dyes that is quite characteristic. The bacUlus of diphtheria grows well upon blood-serum and artificial culture media, at the temperature of the body. It does not have spores. The infection may enter the body in a great variety of ways. It may pass directly from mouth to mouth, or in- directly from objects that have become contaminated with the germs of the disease. The bacilli may be taken into the system with the food, especially milk. The infection may also be taken into the body through the respiratory Digitized by Microsoft® 268 DISINFECTION AND DISINFECTANTS. system, although this is rare. The diphtheria bacillus is not found in the expired breath and the disease is not air- FlG. 64. Bacillus diphtheria. Long Beaded Variety with Pointed Ends AND THE Short Forms. Fig. 65. Bacillus diphtheria. Two Specimens of the Medium and Long Varieties with Clubbed Extremities.— (C«;-/!.r.) borne in the sense that smallpox or typhus fever is. The air may become infected from dried sputum, or from minute Digitized by Microsoft® DISINFECTION FOR THE COMMUNICABLE DISEASES. 269 particles that are sprayed from the mouth in the acts of coughing, speaking, gagging, and other acts of expiration accompanied mth explosive movements. The infection may also be inoculated into wounds of the skin. When the diph- theria bacillus enters the mouth or lodges upon the mucous membranes, it grows and multiplies, setting up the local inflammation which characterizes the disease. The organ- ism usually remains localized at the seat of the lesion, and rarely invades the deeper tissues or the blood. During the course of its growth and multiplication the diphtheria bacillus produces a chemical poison — the diph- theria toxin. It is really this toxin, and not the bacillus itself, that causes the local inflammation and the fibrinous exudate with the death of the cells resulting in the produc- tion of the false membrane. This toxin is a soluble poison and is readily absorbed into the system, giving rise to the fever, prostration, and the nervous symptoms that fre- quently are associated with diphtheria. The bacillus of diphtheria is eliminated from the body with the secretions from the mucous membranes, or with the pus and exudates from wounds, depending upon the seat of the local lesion. The membranes of the throat and larynx being the usual seat of the disease, the infection is most commonly thrown off from the body in the expectora- tion. Therefore, the sputum and all objects which come in contact with the secretions of the mouth must be carefully disinfected in order to prevent the spread of the infection. The evacuations from the bowels and the urine do not need disinfection in this disease. It has been found that many persons in good health have live and virulent diphtheria bacilli in the secretion from their mouths; that is, this organism may grow upon the mucous membranes of the throat and be contained in the Digitized by Microsoft® 270 DISINFECTION AND DISINFECTANTS. expectoration without causing the least inconvenience. Such persons are a constant menace to others who are more susceptible to the disease. The infection may be spread from mouth to mouth by kissing, or, indirectly, by any object that becomes con- taminated with the infected secretions. Handkerchiefs, towels, and other fabrics are especially apt to become in- fected and unless disinfected become sources of danger. Knives, forks, spoons, and other tableware that come in contact with the mouth may carry the infection to other persons who use such articles without previous scalding or disinfection. Play toys are often responsible for the spread of the disease, on account of the habit children have of mouthing such articles. The bacillus of diphtheria grows well in milk, and epi- demics of the disease have been traced to this source. The milk is usually infected at the dairy, but may be rendered safe by boiling or Pasteurization. (See page 214.) The bacillus of diphtheria is readily killed by heat or chemicals. It is destroyed by a moist temperature of 58° C. in a few minutes. Boiling water or steam at 100° C. will destroy the vitality of this infection instantly. It is to be noted that while the bacillus usually dies quickly when dried, under certain circumstances it may retain its vitality a very long time, especially if dried in albuminous matter, such as little bits of the false membrane. This accounts for the long time the infection may persist upon objects that have been contaminated with the secretions from the mouth. The direct sunlight will kill cultures in from thirty to -forty minutes. Any of the ordinary germicidal solutions, employed in the strengths stated for use against non-spore-bearing bacteria, are efficient for the bacillus of diphtheria; for example. Digitized by Microsoft® Fig. 66. % DirilTHERIA Col.'iNlES i.iN At.AR Fll'.. 67. - -V-^'- ■« \ DirnTi-iKKi.-\ IJacili.i in Pukk L'hi.'iuke I'Rom Bluod-skkum — [Fraiike ,.. DlI'LOCOCCUS INTRACEI-LUI.AKIS .MENINGITIDIS IN PuS-CELLS. — [Coiincil- nian. ) Digitized by Microsoft® Digitized by Microsoft® DISINFECTION FOR THE COMMUNICABLE DISEASES. 3II EPIDEMIC CEREBRO-SPINAL MENINGITIS. Cerebro-spinal meningitis is a communicable disease, some- times occurring in very fatal epidemics. The disease is char- acterized by an inflammation of the membranes of the brain and the spinal cord which gives rise to a great variety of symptoms. The cause of the infection is a micrococcus, called the Diplococcus intracellularis meningitidis. This organism is a diplococcus and is found for the most part in the cells of the inflammatory exudate. It resembles the diplococcus of pneumonia very closely in many particulars. It has no spores. The disease is evidently not directly contagious from the sick to the well, nor is the infection transmitted upon the clothing. As the diplococcus causing the disease is only found associated with the inflammation locked up in the cranial cavity and the spinal canal, it is difficult to under- stand how the infection leaves the body of the sick and enters the system of the sound. The infection is not found in the excretions from the body, so long as the membranes of the brain and spinal cord remain intact. It has been suggested that the micro-organism gains entrance into the body through the mucous membrane of the nose. Flexner and Barker suggest that the infection may gain entrance into the system through the intestines, but these views do not seem com- patible with the rapid extension of some epidemics of the disease. So far as we know, the diplococcus of cerebro-spinal men- ingitis is a very frail organism outside of the human body; in fact, it is very difficult to keep it alive and growing upon artificial culture media. It is killed very readily when dried or in contact with heat or weak disinfecting solutions. Digitized by Microsoft® 312 DISINFECTION AND DISINFECTANTS. So little is known of the existence of this infection in nature outside of the body and the channels through which it gains entrance into the system that we cannot apply our disinfectants with any assurance of Umiting the spread of the disease. Our hope in a case like this is to practise a general disinfection of all the discharges, and all the objects that come in contact with the patient, and to give the room a general purification with formaldehyd after the termina- tion of the case. The windows should be screened against insects. In this way we apply all the known principles with the expectation that by a shotgun method we will strike the mark. SMALLPOX. Smallpox, variola or varioloid, is a highly communicable disease known since times immemorial in China and India. It was brought to this country by the Spaniards in the six- teenth century. Smallpox is an acute febrile disease characterized by an eruption which is first papular, then vesicular. The vesicles either drj' up and disappear (varioloid), or they turn to pus- tules and crusts (variola). The period of incubation is a very constant factor in smallpox. The disease makes its appearance between the tenth and the fourteenth day following exposure, usually the twelfth day. Cases have been reported in which the stage of incubation has been as short as five days and as long as twenty days. When the virus is inoculated into the skin (variolation), as was formerly done as a prophy- lactic measure, the local reaction resembling vaccinia ap- pears at the point of inoculation on the third or fourth day, but the general symptoms and fever do not appear until the Digitized by Microsoft® DISINFECTION FOR THE COMMUNICABLE DISEASES. 313 eighth day, and the general eruption on the eleventh day following the inoculation. The cause of smallpox is not known. It is the type of the acute specific infections, and there can be no doubt but that the disease is caused by a living entity or micro-organ- ism. Fortunately we know the disinfecting agents and their strengths necessary to kiU the infectious principle whatever it may be. So certain has our knowledge become that only wilful negligence or ignorance will permit smallpox to be- come epidemic in a community. In short, vaccination, isolation of the sick, and disinfection will certainly prevent the spread of the disease. Smallpox has long been considered a "contagious" dis- ease because it is more readily conveyed by contact between the sick and the well than any other of the communicable diseases of man. We know that the specific virus is thrown off from the patient into the surrounding air, perhaps with the exhaled breath, and certainly from the eruption, whether fluid or dried in the crusts. It is probable, though not proved, that the virus is contained in the blood, but not in the excreta. It is believed that the virus usually enters the system through the respiratory tract — that is to say, the infection is air-borne. The disease may also be caused by introducing some of the fluid secretions of the vesicles or pustules into the skin of a susceptible person. Variolation, which was formerly practised, has given us abundant proof that such material inoculated into injured parts of the skin will repro- duce the disease in all its essential characteristics. Smallpox spreads chiefly through the medium of the sick, more rarely of intermediate persons. It is definitely known that inanimate objects which have come in contact with the patient or the infectious discharges may retain the infec- Digitized by Microsoft® 314 DISINFECTION AND DISINFECTANTS. tion alive and virulent, and communicate the disease to others even after the lapse of a very long time. For ex- ample, blankets, bedding, and clothing which have been used by the patient and afterward packed away without any disinfection have caused the disease in another person who has unpacked or handled these objects months after- ward. Well-authenticated instances are on record where the infection has remained on fomites (inanimate objects) for two years and then given rise to the disease, showing the great vitality of the virus under certain conditions. As far as disinfection for smallpox is concerned, we must be guided largely by the results of practical experience and analogy to other communicable diseases, especially vac- cinia, which is considered a modified form of smallpox, and for our purposes may be regarded as the same disease. Re- searches have shown that the virus of vaccinia is destroyed by heat at a temperature of 54° C. in a short time, also that sulphur dioxid is efficacious in destroying the potency of the virus. We know how very susceptible this virus is to the ordinary germicidal solutions. Therefore it is reason- able to suppose that the active principle of smallpox, what- ever it is, may be destroyed by the same disinfecting agents that are used for non-spore-bearing infections, such as diph- theria, tuberculosis, cholera, typhoid fever, etc. In fact the application of the principles of disinfection based upon this supposition meets with success in actual practice. The disinfection for smallpox must begin at the bedside. It is believed by some that the disease is communicable even before the eruption appears. It is important to keep the skin of the patient clean and anointed with a bland oil or salve to prevent the desquamating epiderm and the dried secretions of the eruption from floating into the air. A disinfectant may with advantage be added to the oil or Digitized by Microsoft® DISINFECTION FOR THE COMMUNICABLE DISEASES. 315 ointment. For this purpose a carbolized vaselin, or olive oil, or a borated or salicylated lard is very useful. The skin may be bathed from time to time with a weak solution of bichlorid or carbolic acid, or one of the hypochlorites. Such measures are grateful to the patient and are a decided help in destroying the superficial infection and of preventing it from leaving the body in a live and active form. As the eruption frequently appears upon the mucous mem- branes, especially of the mouth and throat, the sputum may be contaminated and should be disinfected. The urine and the excreta are not believed to contain the virus, but as they are very apt to become contaminated with the infection from the skin and other sources, they should be disinfected by the methods given for these substances in another por- tion of this volume. The vessels containing these excretions must be carefully disinfected. Smallpox is very apt to be complicated with abscesses and ulcers upon the skin. These sores often suppurate for a long time and the pus discharged from them contains the virus of the disease, and must therefore be disinfected. The hair will need particular attention to prevent the desic- cation and diffusion of the crusts and flakes of epiderm. If the hair is long and the eruption abundant upon the scalp the hair had better be cut to prevent the matting and de- composition of the crusts. In the cutting care should be taken to prevent particles flying about by keeping the hair moist, and gathering it all together in a cloth wet with bi- chlorid I : looo and the whole immediately burned. The infection of smallpox is so readily diffused that not only the objects coming in contact with the patient and his discharges will need treatment, but the entire room and its contents must be disinfected. The room in which the pa- tient is treated should contain only the necessary articles, 23 Digitized by Microsoft® 31 6 DISINFECTION AND DISINFECTANTS. and all carpets, hangings, upholstered furniture, and other objects not necessary for the care and comfort of the patient should be removed. The windows should be screened to prevent the ingress and egress of flies and other insects, for it is reasonable to suppose that flies which come in contact with the eruption may convey the infection on their feet and smeared upon their bodies, to persons in other rooms of the same house or to other houses. It is also well to keep a sheet wet with a solution of bichlorid hanging in the doorway leading from the sick-chamber, and to restrict the communication with the sick-room to a minimum. The room in which a case of smallpox is treated should have all its surfaces mopped at least once a day with an antiseptic solution such as bichlorid i : looo, and dry sweep- ing and dusting must be prohibited, as well as anything which has a tendency to raise the dust. The towels, bedding, body linen, clothing, and other fabrics which have in any way come in contact with the patient or the infection, should be gathered in a sheet wet with a bichlorid solution, and then immediately boiled, steamed, or immersed in one of the disinfecting solutions. The disinfection of the room and its contents after con- tamination with a case of smallpox may best be accomplished with one of the gases, either formaldehyd or sulphur dioxid being available for this purpose. These gases cannot be depended upon for more than a surface disinfection; therefore carpets, hangings, clothing, bedding, upholstered furniture, and other objects needing deeper penetration to purify them must be removed for other treatment appropriate to each object as described in another section. The preparation of the room for the gaseous disinfection is very important and has been described in another place, page 84. In removing objects from the Digitized by Microsoft® DISINFECTION FOR THE COMMUNICABLE DISEASES. 317 room for disinfection care must be taken to carefully wrap them in a sheet wet with bichlorid solution, or, if this is not practicable, to thoroughly disinfect the surface of the object by washing it down with one of the antiseptic solu- tions. CHICKEN-POX. Chicken-pox, or varicella, is an acute communicable dis- ease frequently occurring in epidemics among the children. The disease has no relation to smallpox. It is characterized by a febrile condition and an eruption of vesicles upon the skin. The cause of chicken-pox is not known. The period of incubation is ten to fifteen days. The disease is highly "contagious" in the same sense that smallpox is — that is, by contact between the sick and the well. As far as disinfection is concerned, precisely the same methods and agents recommended for smallpox are appli- cable to this disease. MUMPS. Mumps, or epidemic parotitis, is a communicable disease, sometimes occurring in epidemic form. It is characterized by an inflammation of the parotid gland. The cause of mumps is not known. The period of incubation is from two to three weeks. The disease is communicated from the sick to the well, but how has not been determined. It is supposed that the saliva contains the infective principle, and therefore hand- kerchiefs and other fabrics and objects which come in con- tact with the secretions from the mouth should be disin- fected. Digitized by Microsoft® 3l8 DISINFECTION AND DISINFECTANTS. MEASLES. Measles is a highly communicable disease occurring in epi- demics. It is characterized by a fever, catarrhal symptoms, especially of the mucous membranes of the respiratory tract, and by a rapidly spreading eruption with desquamation of the epidermal layer of the skin. The period of incubation is usually about ten days, but may be as long as twenty days. The cause of measles is not known. From observations made it is very probable that the specific agent is thrown off in the breath of the affected person ; in other words, this may be one of the few air-borne infections. The disease is communicated by the secretions, particularly that of the nose, and there is no doubt but that the desquamating epi- thelial flakes may transmit the infection. In these respects measles resembles smallpox very closely so far as the methods and channels of infection are concerned. As with smallpox, the infection may also be conveyed through a third person, or by fomites — that is, inanimate things. The disinfection for measles is precisely the same as that described in detail for smallpox and need not be repeated here. (See page 312.) SCARLET FEVER. Scarlet fever is a communicable disease occurring in most large communities and from time to time breaking out in epi- demic form, especially among the children. The disease is characterized by a sore throat, a diffuse eruption and desqua- mation of the epidermal layer of the skin, frequently in large flakes. Digitized by Microsoft® DISINFECTION FOR THE COMMUNICABLE DISEASES. 319 The cause of scarlet fever has not been determined. The period of incubation is very variable and not well determined. It may vary from three to twelve days. The disease is communicated directly from the sick to the well, probably through the agency of the fine scaly particles which are diffused with the dust throughout the room. The infectious principle is probably not given off until the erup- tion appears, and there is no doubt that the specific agent is found in and spread by the desquamating skin, and also the sputum. The infection clings with great persistence to clothing of all kinds and to articles of furniture and other objects in the room. In this respect the infection of scarlet fever resembles that of smallpox very closely. Bedding and clothing that have been put away for months and even for years may, unless thoroughly disinfected, convey the infection. Physicians, nurses, and others in contact with the patient may carry the infection to persons at a distance. Epidemics of scarlet fever have also been traced to the milk, and there is little doubt but that this fluid may be responsible for the spread of the disease. As far as the disinfection for scarlet fever is concerned, we must be guided wholly by analogy and by experience. As the disease is spread largely as diphtheria and smallpox are spread, we have applied the same agents and principles for the disinfection of scarlet fever as for these diseases. WHOOPING-COUGH. Whooping-cough is a communicable disease, characterized by paroxysmal spells of coughing that end with a peculiar inspiratory "whoop." The disease occurs in widespread epidemic form and is frequently fatal, especially in young children. Digitized by Microsoft® 320 DISINFECTION AND DISINFECTANTS. The cause of whooping-cough is not known. The period of incubation is variously stated as from two to ten days. The disease is communicated directly from the sick to the well through the secretions of the mouth and the respiratory tract as in the case of diphtheria. There is also reason to believe that the virus from this source may be harbored upon handkerchiefs and towels, in clothing and bedding, and upon furniture and objects in the room, and transmit the disease to other persons. So little is known as to the cause of whooping-cough and the precise method of its spread that we have no accurate scientific data upon which to base our disinfection. All handkerchiefs, towels, eating utensils, and other ob- jects which come in contact with the secretions of the mouth should be boiled or steamed. The room in which the patient is isolated should be frequently mopped with a solution of bichlorid i : looo or carbolic acid 3 per cent. After the symptoms have disappeared the room should be given a general disinfection with one of the gases, either formaldehyd or sulphur dioxid. These measures are based upon general principles and analogy to similar infections of a known nature. INFLUENZA. Influenza is a highly communicable disease, occurring in widespread epidemics. It spreads with greater rapidity than any known infection. In a few weeks a whole continent may be involved. The disease is characterized by fever, catarrhal inflam- mation of the mucous membranes, and prostration. The symptoms are very inconstant. Digitized by Microsoft® DISINFECTION FOR THE COMMUNICABLE DISEASES. 32 1 The period of incubation is stated as from one to four days, oftenest three to four days. The cause of influenza is believed to be the bacUlus de- scribed by Pfeiffer in 1892. It is a very slender, non-motile rod, growing with difficulty upon the culture media used in the laboratory. It does not have spores. The disease is "contagious" in the sense that it is com- municable by contact between the sick and the well. The Fig. 87. Influenza Bacillus. — {Curtis.) infection spreads along the lines of travel. It was believed that the disease has the power of spreading quicker than railroad trains or ships could convey the sick or the infec- tious material, and it was therefore assumed that the causa- tive agent was in the air and was conveyed from place to place as a result of certain ill-defined meteorologic condi- tions. This, however, is probably not the fact. The dis- ease has apparently been limited and kept from institutions by isolation and other precautions, including disinfection. Digitized by Microsoft® 322 DISINFECTION AND DISINFECTANTS. The infection is probably taken into the system through the respiratory tract, although there is little definite evidence to prove this assumption. The bacillus of influenza is found in great numbers in the secretions from the mouth and nose of those suffering with the disease, and the infection is chiefly eliminated through these channels. The bacillus is not found in the blood. The bacillus of influenza is a very frail organism outside of the body; in fact, it is very difficult to keep it alive upon culture media, even under the most favorable condi- FiG. 88. Influenza Bacillus in Sputum. * tions of moisture, temperature, etc. It dies quickly when dried, whether in pure culture or in sputum. A moist tem- perature of 60° C. wUl destroy the infection in ten minutes; boiling water or steam, at once. It is extremely susceptible to germicidal agents when exposed in pure culture. Formaldehyd and sulphur dioxid are trustworthy disinfectants in the strengths and times as stated for the employment of these gases. The chemical solutions in their ordinary strengths as em- ployed for non-spore-bearing infections will kill the bacillus Digitized by Microsoft® DISINFECTION FOR THE COMMUNICABLE DISEASES. 323 of influenza; for example, bichlorid of mercury i : looo, carbolic acid 3 to 5 per cent., tricresol i per cent., formalin 3 to 5 per cent. The disinfection for influenza resembles that recommended for diphtheria or tuberculosis, especially as the infection is largely thrown off from the body in the expectorated matter, and the principles and methods described for those diseases are applicable to this infection. For the treatment of the sputum see page 226. The handkerchiefs, towels, bedding, and other fabrics that come in contact with Ihe infection should be boiled, steamed, or immersed in one of the germi- cidal solutions mentioned above. As the infection of influenza is evidently readily diffused into the air, the sick-room should be given a general puri- fication with one of the gaseous disinfectants, preferably formaldehyd. ERYSIPELAS. Erysipelas is a communicable disease, sometimes occurring in epidemics. It is characterized by a special inflammation of the skin, with fever and all the characteristics of an acute specific infection. The period of incubation is variable, probably from three to seven days. The cause of the disease is the Streptococcus erysipelatis, or the Streptococcus pyogenes, sometimes called the micro- coccus of Fehleisen, who first obtained this organism from the skin of cases of erysipelas in 1883. It grows in chains of minute spherical cells, and can be cultivated at the body temperature only with difficulty upon culture media. The micrococcus of erysipelas does not have spores. It is always found in the inflamed region, especially in the spreading zone of inflammation, The organism usually re^ 24 Digitized by Microsoft® 324 DISINFECTION AND DISINFECTANTS. mains localized at the seat of the lesion, but it may invade the blood and with its toxin give rise to serious and often fatal complications. It is believed that the infection of er}-sipelas always enters the sj'stem through wounds in the skin or mucous mem- branes. These wounds may be such slight fissures or abra- FlG. 89. Various Ai'pearances of Streptococci from Bouillon Cultures. sions as not to be visible to the naked eye. Before the days of asepsis and antisepsis erv'sipelas was a frequent compHca- tion of wounds, and was often found in epidemic form in hospitals and camps. The infection of er>'sipelas is eliminated from the body in the pus and secretions from the seat of the inflammation. Digitized by Microsoft® DISINFECTION FOR THE COMMUNICABLE DISEASES. 325 and perhaps also in the desquamating skin from the inflamed area. Outside of the body the micrococcus of erysipelas is a very fraU organism. It dies and loses its virulence very quickly when dried, especially in the sunshine. It is very suscep- tible to heat and antiseptics. It is killed by a moist temperature between 52° and 54° C. in ten minutes. Boiling water or steam at a temperature of 100° C. destroys the infection at once. Formaldehyd and sulphur dioxid in the strengths and time as stated for the employment of these gases are efficient disinfectants for the micrococcus of erysipelas. It is also destroyed by the ordinary germicidal solutions in the strengths employed for the destruction of the non- spore-bearing bacteria; for example, bichlorid of mercury I : 1000, carbolic acid 3 to 5 per cent., tricresol i per cent., formalin 3 to 5 per cent. The bandages and other dressings from a case of erysipelas should be burned or thoroughly boiled. The bedding, towels, and other fabrics that have come in contact with the patient or the infection must be boiled, steamed, or im- mersed in one of the germicidal solutions. The hands of the nurse and alt objects that have in any way come in con- tact with the infected secretions must be disinfected by methods appropriate for each object. Rooms that have become contaminated with the infection of erysipelas should be given a disinfection with one of the gases, followed by a thorough cleansing. DENGUE. Dengue is a communicable disease occurring in epidemic form in tropical and subtropical regions. The disease is Digitized by Microsoft® 326 DISINFECTION AND DISINFECTANTS. characterized by fever, pain in the joints and muscles, and sometimes a rash. The cause of dengue is not known. The period of incubation is from three to five days. The disease spreads from place to place along the lines of travel — on ships as well as railroads. The infection seems apparently to be in the air (?), for the disease is remarkable in attacking all the members of a community whether they have apparently come in contact with the sick or not. It spreads over a great expanse of territory in a very short time. Practically nothing is known of the method by which the contagion is thrown off from the body, or the channels of infection. As far as known the disease never proves fatal, and few observations have been made upon its pathology. Disinfection is not practised to check the spread of dengue, and as long as we know so little of its nature and the con- veyance of the infection, we could not hope to accomplish much with the ordinary methods of disinfection. The recent work of Graham states that dengue is caused by an animal parasite, similar to the protozoon of malaria, and that the disease is spread by the mosquito. TYPHUS FEVER. Typhus fever is a highly communicable disease, formerly occurring in very severe epidemics. It is now rarely seen. Typhus fever is also called spotted fever, jail fever, camp fever, ship fever, hospital fever. It spreads, as its name indicates, in filthy, overcrowded, and unsanitary places. The disease in former years claimed many victims in Europe and this country, but since modern improvements in sanitation have been introduced into cities and institu- tions, and the misery of poverty has been diminished, there Digitized by Microsoft® DISINFECTION FOR THE COMMUNICABLE DISEASES. 327 seems to be no tendency for the disease to spread, although it is always present in some of the large cities. Typhus fever is an acute, specific, febrile disease, char- acterized by a sudden onset, severe depression, and a rash. The fever usually terminates by crisis about the end of the second week. The cause of typhus fever is not known. The period of incubation is given as twelve days, but it may be less. Typhus fever is believed to be "contagious" in the sense that it is communicated by contact between the sick and the well. When the disease exists in epidemic form, it is the most highly contagious of all the diseases of man. The nurses, physicians, and those who come in contact with the patient are the first to take the disease. Few escape. The specific virus, whatever it may be, seems to be given off into the atmosphere surrounding the patient, perhaps in the exhaled breath. Practically nothing of an exact nature is known as to how the poison is excreted from the body or how the infection is introduced into the system. It is evident that sanitation is much more needed to pre- vent the spread of this disease than disinfection; in fact, while disinfection is practised for typhus fever, there is nothing to indicate that it is efficacious in preventing the spread of the disease. RELAPSING FEVER. Relapsing fever, also called "famine fever" and "seven day fever," is a communicable disease sometimes occurring in epidemic outbreaks. The disease is common in India, and has from time to time extensively prevailed in Europe and Ireland. In 1869 it prevailed as an epidemic in New York Digitized by Microsoft® 328 DISINFECTION AND DISINFECTANTS. and Philadelphia ; since then it has not reappeared in epi- demic form in this country. Relapsing fever is characterized by a sudden onset with a chill, followed by fever lasting about a week. There is then an intermission of the same length of time, followed by a repetition of the febrile paroxysm. The relapses, from which the affection takes its name, may repeat themselves four or five times. The time of incubation appears to be very short, and in some instances the attack appears soon after the exposure. More frequently the time of incubation is five to seven days. Relapsing fever is caused by a spiral-shaped micro-organ- ism in the blood discovered by Obermeier in 1873, and called the Spirochmta obermeieri. It is an actively motile, narrow, spiral filament, found in the blood only during the fever. It has never been grown on artificial media, and nothing is known of its existence in nature outside of the body. The channels of entrance into and the modes of elimina- tion from the body are not known. Relapsing fever develops and spreads under the same conditions that favor typhus fever. Sanitation seems to be more important than disinfection. As the disease may be transmitted by inoculating the blood of the sick into the well, perhaps biting insects convey the infection. GLANDERS. Glanders, or farcy, is a widespread communicable disease of horses, mules, asses, and other animals. It is occasionally communicated to man. In both man and horses it is re- markable for its fatality. The disease is characterized by the formation of infiam- Digitized by Microsoft® Fig. 90. Spirillum of Relapsini; Fevei Fig, 91. Bacillus of Glanhfrs, Showing Irregular Staining. Digitized by Microsoft® Digitized by Microsoft® DISINFECTION FOR THE COMMUNICABLE DISEASES. 33I matory nodules, either in the mucous membrane of the nose (glanders) or in the skin (farcy). The period of incubation of the acute form of glanders in rarely more than three or four days. Glanders is caused by the Bacillus mallei. This organism is a slender, non-motile rod, and grows well upon the arti- ficial culture media used in the laboratory. It does not have spores. The infection may be introduced into the system either through the skin or mucous membrane of the respiratory tract. In the former case the disease is usually communi- cated from the horse to man by contact with the infected discharges, which gain entrance into the system through wounds in the skin, giving rise to the form of the affection known as farcy. The disease is sometimes communicated from man to man. Washerwomen have become infected from the clothes of a patient. When the infection is de- posited upon the mucous membrane of the nose, the form of the disease known as glanders results. The inflammatory nodules which characterize the disease have a tendency to break down, causing ulcers and abscesses, and the infection is eliminated from the body in the pus and secretions from the seat of the lesions. In general the bacillus of glanders is killed by the same agents used against the tubercle bacillus, which it resembles in many particulars. As far as disinfection to prevent the spread of the disease is concerned, the same measures that have been described in detail for diphtheria and tuberculosis are applicable to glanders. Digitized by Microsoft® 332 DISINFECTION AND DISINFECTANTS. ACTINOMYCOSIS. Actinomycosis is a disease of man and some of the domestic animals, more especially cattle, horses, and pigs. The affec- tion is commonly known as "big-jaw," "lumpy-jaw," or "wooden-tongue." The disease is rare in man. Actinomycosis is characterized by a tumefaction and in- flammation of the tongue and adjacent tissues of the jaw. Fig. 92. Ray-fungus of Actinomycosis. Fresh, Unstained Preparation FROM A Case of Lumpy-jaw in a Cow. Diagrammatic. — ( Williavis.) The lips, cheeks, bones, lungs, skin, and other tissues of the body may be affected. When the infection appears in the lungs of man, the disease resembles pulmonary tubercu- losis. There is also an intestinal form of the disease. The cause of actinomycosis is a ray -fungus, the Actino- myces. This organism is a streptothrix, having branching filaments. It may be grown in pure culture on the arti- ficial media used in the laboratory. In the pus and secretions of the lesions are found peculiar Digitized by Microsoft® DISINFECTION FOR THE COMMUNICABLE DISEASES. 333 white or yellowish bodies, visible to the naked eye, that have the appearance of fine grains of sulphur or sand. Under the microscope these little bodies are seen to consist of a rosette of mycelial threads with numerous oval, spore-like bodies in the center. How the organism enters the system is not known. It is doubtful whether the disease may be communicated from man to cattle, or from cattle to man. It seems more prob- able that both man and cattle receive the infection from the same external source. The infection is probably most frequently taken into the mouth with the food. In this way either the tongue or the adjacent tissues of the mouth and jaw become infected through minute wounds, abrasions, or through carious teeth. Barley and rye are looked upon with most suspicion. The fungus or its spores may also enter the system with the drinking water, to cause the abdom- inal form of the disease, or with the dust to cause the pul- monary form. The irritation caused by the presence of the parasite in the tissues sets up a specific inflammation resembling tuber- cles. The nodules have a tendency to break down and the infection is eliminated from the body in the pus and dis- charges from the local lesions. Little is known as to the resistance of the fungus of actino- mycosis, or of its existence in nature outside of the body. The sputum and the dejecta in the abdominal cases should be disinfected in accordance with methods already given. The bandages and other objects which have become soiled with the discharges should be burned or disinfected with steam or boiling water. On account of the presence of spores it will be necessary to use disinfecting agents which will destroy their vitality. See Anthrax and Tetanus. Digitized by Microsoft® 334 DISINFECTION AND DISINFECTANTS. MADURA FOOT. Madura foot is an infection occurring mostly in the prov- ince of Scinde, in India. Several cases have been recognized in this country. The disease is also called mycetoma, Madura disease, fungus foot of India, pied de Madura. The disease is characterized by a specific granulomatous inflammation caused by the fungus, Streptothrix madurcB, similar to the ray-fungus of actinomycosis. The fungus of Madura foot may be obtained in pure culture from the affected nodes. It grows well in acid vegetable infusions. Upon the surface of agar strikingly beautiful, rounded, glazed colonies are formed. They become rose-colored or bright red. Under the microscope this organism is plainly seen to be a true fungus, as it has branching forms. Spores can be distinguished in the long mycelial threads. The fungus gains entrance into the body through wounds in the skin, and by its irritating presence sets up a chronic inflammatory process. The disease is often traced to the prick of a thorn. The feet are usually affected, sometimes the hands, and in one case that has been reported, the shoulders and hip. The onset of the affection is very insidious. Small indu- rated nodules form at the site of the infected part, which is frequently situated upon the pad of soft tissues forming the ball of the foot, or the thumb. These nodes gradually grow larger, until, after the lapse of months, they attain a perceptible size, sometimes to enormous growths. Later, perhaps not until the lapse of a year or two, the inflamed and indiurated mass softens and breaks down, forming abscesses and sinuses. The bones, as well as the soft parts, may be invblved. Digitized by Microsoft® DISINFECTION FOR THE COMMUNICABLE DISEASES. 335 The discharge from the seat of the lesion contains small bodies resembling those found in actinomycosis. These bodies are described as resembling the grains of black gun- powder, coming from that form of the disease known as melanoid mycetoma, or resembling shad-roe, coming from the pale or ochroid variety of the disease. They consist of a dense radiate mycelium, similar to the bodies found in the lesions of actinomycosis. The infective agent is probably eliminated from the body only in the discharges from the seat of the lesion. The disease is probably not communicated directly from man to man. While the mode of entrance of the ray -fungus of mycetoma into the human body has not been deter- mined with certainty, there seems little doubt but that it gains entrance by inoculation into the soft tissues, in a manner similar to actinomycosis. The malady is often traced to wounds in the affected region. While the fungus of mycetoma has been obtained in pure culture from the seat of the lesions, and has been grown on the culture media used in the laboratory, practically nothing is known of its existence in nature outside of the body. The strengths of germicidal agents necessary to destroy its life must be surmised from analogy to other better known spore-bearing fungus growths, as little has been done to test its resistance. The dressings which have become soiled with the dis- charges should be burned. Articles which have become con- taminated with the infection should be boiled, steamed, or subjected to strong germicidal solutions sufficient to kill spores, such as anthrax or tetanus. Digitized by Microsoft® 336 DISINFECTION AND DISINFECTANTS. ANTHRAX. Anthrax is a communicable disease, occurring as a wide- spread infection of the lower animals, especially sheep and cattle. It is occasionally communicated to man. Anthrax is also called malignant pustule, splenic fever, charbon, and wool-sorter's disease. The disease is characterized by a variety of symptoms depending upon the seat of the lesion. If the infection is Fig. 93. Anthrax Bacilli. — (^Baumgarten. ) introduced into the skin, a local reaction results causing the "malignant pustule." The inflammation spreads through the lymphatics and may invade the blood. When the infec- tion is taken into the respiratory tract, it causes a violent inflammation resembling bronchitis or pneumonia, and is called wool-sorter's disease. Sometimes the infection is taken into the intestinal tract, producing symptoms of an intense poison. All forms of the disease frequently result fatally. Anthrax is caused by a typical, non-motile rod, the Bacil- Digitized by Microsoft® DISINFECTION FOR THE COMMUNICABLE DISEASES. 337 liis anthracis. This bacillus has been carefully studied by Koch, Pasteur, and many other scientists, so that it is prob- ably the best known of the pathogenic micro-organisms. The bacillus of anthrax multiplies by fission with great rapidity, and grows abundantly upon the ordinaiy culture media used in the laboratory. Fig. 94. Anthrax Bacilli, Showing Spores. It has spores. After a few days' growth each bacillus develops within itself a highly refractive, oval body, the true endospore. The usual method by which the infection of anthrax enters the -system is through fissures, abrasions, or wounds of the skin. This is especially apt to take place upon the exposed Digitized by Microsoft® 33S DISINFECTION AND DISINFECTANTS. surfaces— Ihe hands, arms, and face— of those who work with hides and other infected objects. The infection may also be taken into the intestinal canal as a result of eating meat or drinking milk of diseased animals. vSmall epidemics have been described as a result of a numlscr of persons eating the flesh of an animal that had had anthrax. The third channel through which the infection may enter the system is through the respiratory tract. This form of the disease Fig. 95. J c 1 ''^' >^ Anthrax Colony. — [Baumgar/en. ) occurs in large establishments in which wool and hair are sorted and cleaned, and is therefore called wool-sorter's disease. The infection of anthrax is eliminated from the body in the pus and discharges froin the vesicles, carbuncles, and broken-down tissue which are frequently found associated with the disease. In the pulmonary form the infection is eliminated from the body in the expectoration. In the Digitized by Microsoft® DISINFECTION FOR THE COMMUNICABLE DISEASES. 339 intestinal variety the discharges from the bowels contain the infective principle. The infection has been conveyed by flies, probably in the same way that these insects spread the infection of typhoid fever. The bacillus of anthrax itself is readily destroyed, but the spores have a high degree of resistance to heat and chemical agents, so that much more powerful disinfectants are re- quired to kill this infection than are required for the non-spore- bearing bacteria, such as diphtheria, cholera, tuberculosis, typhoid fever, plague, pneumonia, etc. The disinfection for anthrax is one of the most difficult problems with which we have to deal. Drying has little effect upon the spores of anthrax. They have been preserved in a dry state for years withoxit losing their vitality and virulence. A dry heat of 150° C. con- tinued for one hour is necessary to kill them. A tempera- ture of 140° C. cannot be trusted to kill the dry spores even after four hours' exposure. As far as moist heat is concerned, nothing less than boil- ing water or steam at 100° C. can be considered trustworthy. It is true that the spores suspended in a liquid are usually killed by the boihng temperature in a few minutes, but occasionally anthrax spores are met with which show a high degree of resistance to these conditions, and it is therefore necessary to prolong the exposure to two hours in order to insure penetration. Anthrax spores may be killed with superheated steam with certainty, and this is the most trustworthy method of dealing with the infection. An exposure of fifteen minutes to steam at 120° C. or twenty minutes to steam at 115° C. is quite sufficient. Formaldthyd gas and sulphur dioxid are incapable of Digitized by Microsoft® 340 DISINFECTION AND DISINFECTANTS. destroying the infection with certainty and are therefore totally inapplicable. It requires one hour for a i : looo solution of bichlorid to kill anthrax spores. A i : 500 solution acts more quickly and should be used in dealing with this infection. Carbolic acid cannot be depended upon to destroy the spores of anthrax, and therefore is not applicable for dis- infection against this disease. Tricresol in 2 per cent, solu- tion or lysol in 2 per cent, solution may be used. It requires a 33 per cent, solution of formalin (containing 40 per cent, formaldehyd) to destroy anthrax spores in fifteen minutes. A 15 per cent, solution takes one hour and a half to accomplish the same result. The strengths of the disintfecting solutions as here given are all based upon their germicidal action at ordinary tem- peratures. Their power is very much increased by using them hot, and it is recommended always to use these solu- tions at or near the boiling-point in attacking such a resistant infection as anthrax spores. It will be found safest to burn the bandages, dressings, and other objects of little value that have become soiled with the discharges from a case of anthrax. The bedding, clothing, and other fabrics that have become contaminated must be disinfected by steam or by immersion in one of the strong hot germicidal agents, using these agents under the condi- tions which are known to destroy the spores. The disinfection of cadavers or carcasses dead of anthrax is a very important and difficult matter. The infection may live for years in the soil, which becomes contaminated from the bodies of animals even when buried deeply. The worms have been known to bring the spores in their intestinal canal to the surface, thereby giving rise to fresh infection after the lapse of a long time after the infected carcass was buried. Digitized by Microsoft® DISINFECTION FOR THE COMMUNICABLE DISEASES. 341 Burning is the best method of disposing of bodies dead of anthrax. This is not always practicable in the case of large animals, such as sheep and cattle. In districts where the disease prevails isolated cemeteries have been provided in order to limit the infection to a definite area. In regions where many animals die of the disease they are sometimes treated in a bath of strong sulphuric acid, and the resulting products used commercially. In isolated cases it is some- times possible to boil the carcass piecemeal. If the bodies are buried it is important not to bleed, open or mutilate the carcass in any way, for the reason that the spores of anthrax do not form in the body unless the bacilli have access to the oxygen of the air. TETANUS. Tetanus is a communicable disease prevalent in certain locahties and sometimes occurring in epidemic form in in- stitutions, camps, or among the newly born children. The disease is characterized by cramps of the voluntary muscles, beginning with the muscles of the jaw, which gives the name of lockjaw or trismus to the affection. The period of incubation is usually within ten days. Tetanus is caused by the bacillus of tetanus, first isolated by Kitasato in 1 889. This organism is a slender rod, actively motile, and sometimes grows out into long filaments. It has spores. They are small, round, glistening bodies, appearing upon one end of the bacillus, and giving it the shape of a pin. The spores become detached from the bacilli and have an independent existence, and a very high degree of resistance to heat, germicidal agents, and external influences. Under favorable conditions, such as the presence of moisture and albuminous matter and the absence of oxy- gen, the spores are capable of germinating into bacilli. 25 Digitized by Microsoft® 342 DISINFECTION AND DISINFECTANTS. A peculiarity of the bacillus of tetanus is that it cannot grow and multiply in the presence of oxygen. This gas, which is so necessary to the life of almost all animals and plants, acts as a violent poison or strong germicide to the bacillus of tetanus. Even minute traces of oxygen will prevent the growth of tetanus, and in higher percentages, such as the amount of the gas as found in the atmosphere. Fig. 96. Tetanus Bacilli, Showing Spores. will kill the bacillus at once. On the other hand, oxygen has no effect upon the spores of this infection. The disease is always contracted through wounds, which may be of a trifling character. Deep or punctured wounds are more apt to develop tetanus because the oxygen of the air prevents the development and acti\'ity of the organism should it lodge upon the surface. There is very little reaction or inflammation set up at the seat of the inocula- tion. The organism germinates and multiplies locally in the wound without invading the blood or the deeper tissues. Digitized by Microsoft® DISINFECTION FOR THE COMMUNICABLE DISEASES. 343 The symptoms of the disease result from the formation of a poison called the tetanus toxin, which is soluble and is absorbed into the system and produces its baneful action upon the nervous matter. The toxin of tetanus, which is produced by the growth and multiplication of the bacillus within and without the body, is one of the most violent poisons known. An infinitesimally small amount is sufficient to kill a susceptible animal. The infection is eliminated from the body in the pus and discharges from the wound. The infection is kept alive and spread largely owing to the fact that many of the lower animals, particularly horses, are susceptible to the disease. The spores are taken with the hay, grass, and other food of these animals into their intestinal canals, where they germinate and multiply in great numbers, and are passed out in the manure. In this way the soil of almost all inhabited localities becomes contami- nated with the infection of tetanus. The manure from horses or rich garden earth inoculated under the skin of a mouse or susceptible animal will in the great majority of cases cause the disease. The disinfection of tetanus resolves itself into the de- struction of the spores. In general the degree of resistance of these spores resembles those of anthrax very closely, and the methods of disinfection are the same. Tetanus spores retain their vitality for months in the soil, in manure, and in putrefying materials. Drying has little effect upon them. A dry heat of 150° C. continued one hour is necessary to kill them with certainty. They withstand a moist temperature of 80° C. for one hour, but are killed by boiling water or by steam at 100° C. in a few minutes. In actual practice it is necessary to expose objects to boiling water or to steam no less than two Digitized by Microsoft® 344 DISINFECTION AND DISINFECTANTS. hours in order to insure penetration and the destruction of the spores. Steam under pressure is the most reUable disinfecting agent we possess for this resistant infection. An exposure of fifteen minutes to steam at a temperature of 120° C, or twenty minutes to steam at a temperature of 115° C, will surely kill the spores. A 5 per cent, solution of carbolic acid requires fifteen hours to kill tetanus spores and is therefore inapplicable as a disinfectant for this disease. Tricresol or lysol in 2 per cent, solution may be used, with an exposure of two hours. The spores show a high degree of resistance to a i : 1000 solution of bichlorid of mercury. In actual practice a I : 500 solution should be used. Germicidal solutions are so much more powerful when used hot that it is strongly recommended to use them at or near the boiling-point. Formaldehyd gas and sulphur dioxid cannot be depended upon to destroy tetanus spores and are therefore totally inapplicable as disinfectants for this disease. Digitized by Microsoft® APPENDIX. « *hO •w « t.Sj Ij !^ t>, ^ i^ BOILING POINTIOO FREEZING POINT O- — aiD — = 200 = s s ^ I90 = = = _ ^ ISO = ~ E = 170 = — ^= E ^ 160 = ■ — E E = 150 = ^= ^ ^ l*-0 = ■ — = ^ p 130 = E ^ = — ^ no ^ — = = E ^ 100 = ^ ^ — = 90 ^ — E ^ no = = — n = 70 = — = 60 = E = = = 50 ^ — = = — — /(,^> — E ^ ^ = ^ E = = = =^ in = = = — ~ =^bKO=t= :=^ = E = = 10 = = = lO ^ eo BOILING POINT 70 60 ^ ^ 30 O FREEZING POINT 10 ^=^ 1 20 Comparative Scale OF Swedish German 8. French PROPORTION a (ill ) : 5 ; tf Digitized by Microsoft® INDEX. Aceto-arsenite of copper, 178 Acetozone, 36 Acid, carbolic, 156 Actinomyces, 332 Actinomycosis, 332 Aerobic bacteria, 143 Air, disinfection of the, 191 expulsion from Kinyoun- Francis chamber, 60 expulsion from steam dis- infectors, 45 Ambulances, 198 Ammonia for neutralizing formal- dehyd, 81 retort for steam chamber, 62 Amoeba dysenteriae, 266 Anaerobic bacteria, 143 Animal parasites, 25 Anopheles mosquito, 293 Anthrax, 336 Antiseptics, 146 Antiseptic substances, 19 Arnold steam steriUzer, 47 Arsenic, 178 Arsenite of copper, 178 of lead, 179 Asepsis, definition, 19 Asiatic cholera, 258 Autoclave for disinfecting spu- tum, 228 for evolving formaldehyd, 93 for steam under pressure, 55 Bacilli, 24 Bacillus anthracis, 336 diphtheriae, 267 dysenteriae, 265 icteroides, 300 Bacillus leprae, 291 mallei, 331 of glanders, 331 of influenza, 321 of tetanus, 341 pestis, 275 tuberculosis, 280 typhosus, 249 Bacteria, 24 Ballast, 241 Bandages, 193 Bathing water, 244 Baumgarten, 336 Bedding, 195 Bed linen, 193 Beds, 194 Behring, 147, 172 Benzozone. See Acetozone Bert, 143 Bichlorid of mercury, 152 Big-jaw, 332 Bisulphid of carbon, 181 of Ume, 185 Black death, 274 Blunt, 36 Body linen, 193 BoiUng, 41 water, 42 Books, 196 Brushes, 195 Bubonic plague, 274 Buchner, 34 Buhach, 182 Bulbs, 207 Burning, 37 C. Cadavers, 197 Calcium hydrate, 165 hypochlorite, 169 oxid, 165 347 Digitized by Microsoft® 348 INDEX. Camp fever, 326 Caps, 210 Carbolic acid, 156 for excreta, 205 Carbon bisulphid, 181 dioxid against rats, 188 Cargo, 239 Carpets, 200 Carriages, 198 Cars, 198 cattle, 219 flat, 218 freight, 218 parlor, 219 railroad, 218 sleeping, 220 Casks, water, 239 Cattle cars, 219 Centigrade scale, 345 Cerebro-spinal meningitis, 311 Ceresole, 207 Chamberland, 169 Charbon, 336 Charcoal as a deodorant, 20 Chemical solutions, general con- siderations, 145 methods of using, 149 Chicken-pox, 317 Chlorid of Hme, 167 of zinc, 171 Chlorin, 141 Chlorinated lime, 167 for excreta, 204 Cholera, 258 mild cases spread the infec- tion, 27 Christen, 46 Cisterns, 246 Cleanliness, 20 Clothing, 199 Coaches, day, 219 Coal oil, 180 Cocci, 24 Colors, 200 Combs, 202 Comma bacillus, 261 Communicable disease, definition, 25, 26 Consumption, 280 Contagious disease, definition, 25, 26 Copperas, 170 Cotton, 201 Cremation, 38 Creolin, 159 Cresols, 158 Croupous pneumonia, 304 Culex mosquito, 295 Currency, 215 Curry, 277 Curtains, 202 Cyclops, 304 D. Danyz' virus, 188 Day coaches, 219 Dead bodies, 197 Dengue, 325 Deodorant, definition, 19 Dieudonne, 36 Digester, 55 Dilution, 17-20 Diphtheria, 266 mild cases spreading the dis- ease, 26, 27 Diplococcus intracellularis menin- gitidis, 311 pneumonise, 304 Disease spread through third per- son, 27 Disinfectants, gaseous, 83 Disinfecting chamber, steam, 57 Kinyoun-Francis, 57 Disinfection, definition, 17, 18 excess of actual requirements necessary, 32 Doty, 180 Downes, 36 Draperies, 202 Dry dusting, 20 earth, 206 heat, 38 and formaldehyd in par- tial vacuum, 79, 110 Dryness, 20 Dry- wall sterilizer, 38 Dysentery, 265 Earth, dry, 206 Eberth bacillus, 249 Ejector for vacuum steam cham- ber, 62 Electricity, 36 Electric light, 34 thermometer, 70 Digitized by Microsoft® INDEX. 349 Electrolysis, 37 Elephantiasis, 302 Enteric fever, 249 Epidemic cerebro-spinal menin- gitis, 311 parotitis, 317 Erysipelas, 323 Esmarch, von, 36 Excreta, 202 F. Fahrenheit scale, 345 Famine fever, 327 Farcy, 328 Feces (excreta), 202 Fembach, 169 Ferrous sulphate, 170 for excreta, 205 Filaria bancroftii, 303 diuma, 303 dracunculus, 304 medinensis, 304 perstans, 303 sanguinis hominis, 302 Filariasis, 302 Filters for water, 243 Finlay, 297 Fire, 37 Fisher, 142 Flat cars, 218 Flax, 212 Flies spreading typhoid fever, 250 Floors, 207 Flowers of sulphur as an insecti- cide, 184 Fomites and yellow fever, 300 Food, 206 Foote, 171 Formaldehyd attachment to steam chamber, 62 disinfection by heating para- form, 117 by spraying, 112 with autoclave under pressure, 93 with generator, 105 with kimp, 105 with retort without pres- sure, 98 dry heat in partial vacuum, 79, 110 gas, 87 as a deodorizer, 89 as an insecticide, 185 26 Formaldehyd gas a surface disin- fectant, 91 chemical composition, 88 effect of temperature, 90 effect on bacteria, 91 effect on silk, wool, cot- ton, etc., 89 effect on spores, 91 necessity of moisture, 90 not an insecticide, 92 specific gravity, 88 toxicity, 92 neutralizing with ammonia, 81, 92 sprinkler, 113 FormaUn, 88 composition of, 89 deterioration of, 89 disinfector, 117 for excreta, 205 lamp, 117 reaction of, 90 solutions, 160 spraying method, 112 Formic aldehyd, 87 Formol, 88 Freight cars, 218 Fruits, 207 Fulton, 137 Fungus foot of India, 334 Fur, 211 Fiirbringer'smethodfor hands, 209 Furniture, 208 upholstered, 208 Garbage, 38 Gaseous disinfectants, 83 Gauze, 193 Geddings, 153 Generator, formaldehyd, 105 Geppert, 154 Germicide, definition, 19 Glanders, 328 Glassware, 209 Globig, 46 Graham, 326 Green vitriol, 170 Gueran, 162 Guinea worm, 304 H. Haematozoa malariae. Hands, 209 292 Digitized by Microsoft® 35° INDEX. Hangings, 202 Hankin, 277 Hansen, 291 Harrington, 159 Hats, 210 Hay bacillus in streaming steam, 46 Heat, dry, 38 moist, 41, 42 Heiden, 147 Hermite, 37 Hides {see Leather), 211 Hinds, 181 Holds of vessels. See Vessels Hold, the, 237 Hospital fever, 326 Hot-air sterilizer, 38 Household oven, disinfecting in, 41 Houses, 210 Howard, 180, 181 Hydrocyanic acid, 137 gas, as an insecticide, 187 Hydrogen peroxid and light, effect on germs, 36 Hyperoxids, 36 Hypochlorites, 169 I. Immunity and spread of disease, 26 Inanimate things spreading in- fection, 28 Infectious disease, definition, 25, 26 Influenza, 320 Insecticides, 175 Insect powder, 182 Inspection, 30 Installation of electric thermom- eters, 72 of steam chambers, 73 Instruments, musical, 216 surgical, 211 Intermediate host, 25 Ions, 148 Iron vitriol, 170 Jail fever, 326 Janowsky, 35 K. Kalbrunner, 182 Kelley, 209 Kerosene, 180 Kitasato, 341 Klebs, 267 Klebs-LoefBer bacillus, 267 Koch, 35, 164, 170, 172, 261, 280, 285, 337 steamer, 49 Kronig, 149, 154, 164 Kuhn formaldehyd lamp, 106 Labarraque's solution, 169 Lamp, formaldehyd, 105 La Place, 154 Latent cases spread disease, 26 Lavaran, 292 Lead arsenite, 179 Leather, 211 Ledoux-Lebard, 35 Leitz, 170 Lentz formaldehyd generator, 103 Leprosy, 288 Letters. See Mail Liborius, 166 Light, 20 electric, 34 rays, effect on germ life, 34 Lime, 164 bisulphid of, 185 chlorid of, 167 chlorinated, 167 for excreta, 202 milk of, 165 slaked, 165 Linen, 212 Lipol for excreta, 205 Liquid sulphur dioxid, 124 Lithographs. See Pictures Lobar pneumonia, 304 Lockjaw, 341 London purple, 178 Lucas-Champonniere, 143 Lumpy-jaw, 332 Lupus, 280 Lysol, 159 M. Mackintoshes, 226 Madura disease, 334 Digitized by Microsoft® INDEX. 351 Madura foot, 334 Mail, 212 Malaria, 291 Malignant pustule, 336 Manson, 303 Marlatt, 178, 181, 183 Mattresses. See Bedding McClintock, 174 Measles, 318 Meats, 206 Medicated soaps, 173 Meningitis, 311 Mercury, bichlorid of, 152 Merk steam disinfector, 54 Merk's thermometer, 7l Metacresol, 159 Methods of using chemical solu- tions, 149 Micrococcus lanceolatus, 304 of erysipelas, 323 pasteuri, 172 Migneco, 35 Mild cases spread infection, 26, 27 Milk, 214 of lime, 165 for excreta, 203 spreading typhoid, 253 Mink, 34 Miquel, 170, 172 Moist heat, 41, 42 Money, 215 Mosquitos and malaria, 292 and yellow fever, 297 Mumps, 317 Munson, 142, 171 Musical instruments, 216 Mycetoma, 334 N. Natural disinfecting agents, 20 Neutralizing formaldehyd, 81 Nipples, rubber, 226 Novy, 36 Nuttall, 276 O. Orthocresol, 159 Oven, cooking, disinfecting in, 41 Oxygen, 142 and light, effect on germs, 36 Ozone, 143 P. Paintings, 217 Paracresol, 159 Paraform, 87 Paraformaldehyd, 87 Paris green, 178 Park, 162 Parlor cars, 219 Pastels, 217 Pasteur, 143, 337 Pasteurization, 215 Patient, the, 216 Paul, 149, 154, 164 Pansini, 34 Persian insect powder, 182 Peste, 274 Petroleum, 180 Pfeiffer, 321 Pfuhl, 204 Photographs, 217 Phthisis, 280 Physical agents, 33 Pictures, 217 Pied de Madura, 334 Pigments (see Colors), 200 Pillows. See Bedding Pipes, water, 245 Place infection theory, 297 Plague, 274 Pneumobacillus of Friedlander, 308 Pneumococcus, 304 Pneumonia, 304 Portable sulphur furnace, 137 Potassium permanganate, 163 Pot method of burning sulphur, 122 Preparation of room for gaseous disinfection, 84 of rooms, 223 Pressure in steam chambers, 70 Proskauer, 142 Protozoa, 25 Pulverizer, 151 Pump for bichlorid solution, 150 Pyrethrum, 182 Pyrometer, 72 Q- Quicklime, 164 R. Rags, 217 Railroad cars, 218 Digitized by Microsoft® Digitized by Microsoft® Digitized by Microsoft® Digitized by Microsoft® MEDICAL BOOKS There have been sold more than 140,000 copies of Gould's Dictionaries See Page 12 P. Blakistgn's Son & Company PUBLISHERS OF MEDICAL AND SCIENTIFIC BOOKS 1012 WALNUT STREET, PHILADELPHIA Digitized by Microsoft® Montgomery's Gynecology A PRACTICAL TEXT-BOOK A modern comprehensive Text-Book. By Edward E. Montgomery, m.d., Professor of Gynecology in Jefferson Medical College, Philadelphia; Gynecologist to the Jefferson and St. Joseph's Hospitals, etc. 527 Illustrations, many of which are from original sources. 800 pages. Octavo. Cloth, ^5.00 ; Leather, ^6.00 *^.* This is a systematic modern treatise on Diseases of Women. The author's aim has been to produce a book that will be thorough and practical in every particular. The illustrations, nearly all of which are from original sources, have for the most part been drawn by special artists who, for a number of months, devoted their sole attention to this work. " The book if; one that can be recommended to the student, to the general practitioner — who must sometimes be a gynecologist to a certain extent whether he will or not — and to the specialist', as an ideal and in every way complete work on the gynecology of to-day — a practical work for practical workers." — The Jour- nal of the American Medical Association. Byford's Gynecology Third Revised Edition A MANVAL FOR. STVDENTS AND PHYSICIANS By Henry T. Byford, m.d.. Professor of Gynecology and Clinical Gynecology in the College of Physicians and Sur- geons of Chicago ; Professor of Clinical Gynecology, Women's Medical School of Northwestern University, and in Post-Graduate Medical School, etc. Third Edition, En- larged. 363 Illustrations, many of which are from original drawings and several of which are Colored. l2mo. Cloth, ;?3.oo " As a book to help the student to quickly review what ought to be gotten up, so as to be prepared for the early examination , it is of great service. Such a book would also make a most excellent text- book for the college class room."— F/r^jKra Medical Semi-Monthly Richmond. Digitized by Microsoft® By JAMES TYSON. M, D.. Professor of Medicine, University of Pennsylvania, Physician to tlie Philadelpliia Hospital, etc. The Practice of Medicine. Second Edition. A Text-Book for Physicians and Students, with Special Ref- erence to Diagnosis and Treatment. With Colored Plates and many other Illustrations. Second Edition, Revised and Enlarged. 127 Illustrations. 8vo. 1222 pages. Cloth, ^5. 50; Leather, $6. 50; Half Russia, ^7.50 *^f.* This edition has been entirely reset from new type. The author has revised it carefully and thoroughly, and added much new material and 37 new illustrations. "We are firmly convinced that at the present time Dr. Tyson's book on Practice can be most heartily commended to both the practi- tioner and student as a safe, reliable, and thoroughly up-to-date guide in the practice of medicine." — The Therapeutic Gazette. " The clinical descriptions are clear and full, and the methods of treatment described are those generally recognized as being the most modern and satisfactory." — The London Lancet. Guide to the Examination of Urine. Tenth Edition. For the Use of Physicians and Students. With Colored Plate and Numerous Illustrations Engraved on Wood. Tenth Edition, Revised, Enlarged, and in many parts entirely rewritten. 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'* The author approaches bis subject from a practical point of view and the little work will prove a good friend to the student." — The American Journal 0/ the Medical Sciencee. 3 Digitized by Microsoft® Morris^ Anatomy Rewritten — Revised — Improved WITH MANY NEW ILLUSTRATIONS Out of I02 of the leading medical schools 60 recommend " Morris." It contains many features of special advantage to students. It is modern, up-to-date in every respect. It has been carefully revised, the articles on Osteology and Nervous Syslem having been rewritten. Each copy con- tains the colored illustrations and a Thumb Index. Octavo. With 83S Illustrations, of which a large number are printed in colors CLOTH, $6.00 : LEATHER, $7.00 " The ever-growing popularity of the book with teachers and stu- dents is an index of its value, and it may safely be recommended to all interested." — From The Medical Record, New York. ** Of all the text-books of moderate size on human anatomy in the English language, Morris is undoubtedly the most up-to-date and accu- rate.*' — B'rom Ike Philadelphia Medical Journal. McMurrich — Embryology Nearly Ready. 276 Illustrations A Text-Book for Medical Students. By J. Playfair McMuKRiCH, Professor of Anatomy, Medical Department, University of Michigan. Ready Octoher ist. Digitized by Microsoft® NINTH EDITION POTTER'S MATERIA MEDICA, PHARMACY, AND THERAPEUTICS An Exhaustive Handbook Including the Action of Medicines, Special Therapeutics of Disease, Official and Practical Pharmacy, and Minute Direc- tions for Prescription Writing, etc. Including over 650 Prescriptions and Formulse. By Samuel O. L. Potter, M.A., M.D., M.R.C.P. (Lond.), formerly Professor of the Principles and Practice of Medicine, Cooper Medical Col- lege, San Francisco ; Major and Brigade Surgeon, U. S. Vol. Ninth Edition, Revised and Enlarged. 8vo. With. Thumb Index in each copy. Cloth, I5. 00; Leather, ;?6.oo *^*This is the most complete and trustworthy book for the use of students and physicians. Students who pur- chase it will find it to contain a vast deal of ijiforraation not in the usual text-books arranged in the most practical man- ner for facilitating study and reference. It cannot be sur- passed as a physician's working book. WHITE AND WILCOX. Materia Medica, Pharmacy, Pharmacology, and Thera- peutics. Fifth Edition. A Handbook for Students. By W. Hale White, m.d., F.R.C.P., etc.. Physician to, and Lecturer on Materia Medica and Therapeutics at, Guy's Hospital, etc. Fifth American Edition, Revised by Reynold W. Wilcox, M A , M. D. , LL.D. , Professor of Clinical Medicine and Thera- peutics at the New York Post-Graduate Medical School and Hospital ; Visiting Physician, St. Mark's Hospital ; Assist- ant Visiting Physician, Bellevue Hospital. l2mo. Cloth, JS3. 00; Leather, IS3. 50 5 Digitized by Microsoft® SUBJECT [INDEX. Gould's Medical Dictionaries, = - Page 12 Morris' Anatomy, New Edition, - Page 4 Compends for Students, = = - Page 26 SUBJECT PAGE Alimentary CanaI(seeSurgeiy) 23 Anatomy 7 Anesthetics iS Autopsies (see Pathology) 20 Bacteriology (see Pathology).. 20 Bandaging (see Surgery) 23 Blood, Examination of 20 Brain 8 Chemistry. Physics 8 Children, Diseases of 10 Climatology 18 Clinical Charts 24 Compends 26 Consumption (see Lungs) 15 Cyclopedia of Medicine 12 Dentistry n Diabetes (see Urin. Organs).. 24 Diagnosis 10 Diagrams (see Anatomy) 7 Dictionaries, Cyclopedias 12 Diet and Food 18 Disinfection 15 Dissectors 7 Ear 13 Electricity 13 Embryology 7 Emergencies 23 Eye 13 Fevers 14 Food 18 Formularies 21 Gynecology 25 Hay Fever 24 Heart 14 Histology 14 Hydrotherapy 18 Hygiene 15 Hypnotism 8 Insanity 8 Intestines 22 Latin, Medical (see Miscella- neous and Pharmacy) 18, 20 Life Insurance 18 Lungs 15 Massage 16 Materia Medica x6 S0BJECT. PAGE Mechanotherapy 16 Medical Jurisprudence 17 Mental Therapeutics 8 Microscopy 17 Milk Analysis (see Chemistry) 8 Miscellaneous 18 Nervous Diseases 18 Nose a4 Nursing 29 Obstetrics 20 Ophthalmology 13 Organotherapy 18 Osteology (see Anatomy) 7 Pathology 20 Pharmacy so Physical Diagnosis 11 Physical Training. 16 Physiology 21 Pneumotherapy 18 Poisons (see Toxicology) 17 Practice of Medicine 22 Prescription Books (Pharm'y), 21 Refraction (see Eye) „. 13 Rest 18 Sanitary Science 15 Skin , 23 Spectacles (see Eye) 13 Spine (see Nervous Diseases) 18 Stomach,. k 22 Students' Compends 26 Surgery and Surg'l Diseases, 23 Teuinological Books 8 Temperature Charts 24 Therapeutics 16 Throat 24 Toxicology 17 Tumors (see Surgery) 23 U. S. Pharmacopoeia 21 Urinary Organs 24 Urine 24 Venereal Diseases 25 Veterinary Medicine 25 Visiting Lists, Physicians*. {Send for Special Circular.) Water Analysis 15 Women, Diseases of. 25 Self-Examination for Medical Students. 3500 Questions on Medical Subjects, with References to Standard Works in which the correct replies will be found. Together with Questions from State Examining Boards. 3d Edition. Paper Cover, 10 cts. Digitized by Microsoft© SUBJECT CATALOGUE OF MEDICAL BOOKS. 7 SPMCIAIt NOTM' — The prices given in this catalogue are netf no discount can be allowed retail purchasers under any considera- tion. This rule has been established in order that everyone will be treated alike, a general reduction in former prices having been made to meet previous retail discounts. Upon receipt of the advertised price any book will be forwarded by mail or express, all charges prepaid. ANATOMY. EMBRYOLOGY. MORRIS. Text-Book of Anatomy. Revised and Enlarged Edi- tion. 838 Illustrations, 269 of which are printed in coiors. 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