' ■ • i'^;.i!.it:'3')A' CORNELL UNIVERSITY. THE THE GIFT OF ROSWELL P. FLOWER FOR THE USE OF THE N. Y. STATE VETERINARY COLLEGE. 1897 Cornell University Library RA 761.R54 Disinfection and disinfectants (an intro 3 1924 000 230 916 Cornell University Library The original of tiiis book is in the Cornell University Library. There are no known copyright restrictions in the United States on the use of the text. http://www.archive.org/details/cu31924000230916 Disinfection and Disinfectants AN INTRODUCTION TO THE STUDY OF. Disinfection and Disinfectants (AN INTRODUCTION TO THE STUDY OF). TOGETHER WITH AN ACCOUNT OF THE CHEMICAL SUBSTANCES USED AS ANTISEPTICS AND PRESERVATIVES. LIBRARY. SAMUEL RIDEAL, D.Sc.(Lond.), KBLLOW OP CNIVEKSITT COILESB, LONDON; FELLOW OP THE INSTITUTE OE CHEMISTEY AND OP THE OHEMIOAl SOOIETT; MEMBER OP THE SAHITAUT INSTITUTE OP OKEAT BRITAIN AND OP THE SOOIETT OP PUBLIO ANALYSTS ; EXAMINER IN CHEMISTRY TO THE ROYAL COLLEGE OP PHYSICIANS ; FORMERLY LECTURER ON CHEMISTRY IN ST. GEORGE'S HOSPITAL MEDICAL SCHOOL; PUBLIC ANALYST FOR THE LEWISHAM DISTRICT BOARD OP WORKS, ETC. LONDON: CHARLES GEIPHN AND COMPANY, LIMITED. PHILADELPHIA : J. B. LIPPINQOTT COMPANY. 1895. [All Rights Reserved.] PREFACE. No recent attempt has been made to summai'ise and review the very voluminous literature on the subject of Disinfection which is scattered through our own and foreign Scientific and Medical publications, and, notwithstanding the rapid develop- ment of Sanitary Science in this country, there does not exist at the present time^ in the English language, any book which deals exclusively with the composition of Disinfectants. The present volume may, therefore, supply a want which has been felt, not only by the chemist and bacteriologist, but also by all those who, like medical officers of health and borough surveyors, are concerned with the practical work of Disinfection. Owing to the attention which has been given to bacterio- logical science during the last ten years, the methods of Disinfection are now being reviewed under the more exact conditions which this knowledge has rendered possible. The time is not far distant when the importance of the thorough disinfection of all suspected areas will be fully realised by local authorities, and when all such work will be entrusted to specially qualified men, instead of being regarded as a subsidiary duty of the inspector of nuisances. The Sanitary Institute of Great Britain has for some years insisted that the duties of a Sanitary Inspector are such as to necessitate a considerable amount of practical experience and scientific knowledge. If, as at present, the proper carrying out of the work of Disinfection forms part of their duties, the responsi- bility of such men is considerably augmented. It has become customary in many districts for the public b PREFACE. analyst to advise the sanitary committee on the chemical composition of new disinfectants, and, although this practice should without doubt be generally adopted, it must not be forgotten that a continuous control over the strength and bactericidal activity must be maintained after any particular disinfectant has been finally selected. The laudable attempts of the medical officers of health in some districts to stamp out sporadic outbreaks of infectious disease so soon as they are notified to them, are to a con- siderable extent nullified by the slackness which obtains in neighbouring areas, where a lavish display of untested disin- fectant powders in the street gullies, or the use of a strongly smelling or high-coloured fluid of unknown composition, is relied upon to satisfy the public demand for hygienic condi- tions of life. The following pages may help in discriminating between useful disinfection and the futile attempts which give a false sense of security to many localities in the time of danger. I am indebted to Mr. H. B. Ransom, A.M.Inst.O.E., for the principal portion of the chapter on Disinfection by Heat, and his practical acquaintance with the engineering details of different forms of disinfecting plant has enabled me to give this section much greater value than it otherwise would have possessed. For several suggestions and the account of methods for the bacteriological examination of disinfectants, I have to thank my former colleague. Dr. C. Slater, of St. George's Hospital; and my thanks are also due to Dr. Louis Parkes, the Medical Officer of Health for Chelsea, for advice and for his kindness in reading the proof sheets. SAMUEL EIDEAL. Westmixstbb, June, 1895. TABLE OF CONTENTS. Definition of terms, Primitive modes of disinfecting, Disinfection in the Middle Ages, Bacteriology, Chapter I.— Introductory. FASE PAQS 1 Methods of dealing with bacteria, 5 2 1. By exclusion, ... 5 3 2. ,, removal, . . 6 3 3. ,, destruction, ... 7 Chapter II.— Meehanieal Disinfection. Insufficiency of deodorisation, Light, . . . Mechanical purification of gases and liquids, . Carbon, . Sawdust, Clay, Infusorial earth, 7 Ashes and cinders, 13 8 Gypsum 13 Sand filtration, . 14 10 Stone filters, . . . . 15 10 Clark's softening process. 15 13 Other ,, processes. 15 13 Desiccation, 1& 13 Chapter III.— Disinfection by Heat. Thursfield's appar- Heat as a disinfectant, . . 19 Conditions required in a disinfector, 23 Modes of dealing with disinfection, 27 Time and steam conditions re- quired for disinfection, . . 29 Experiments on the penetrating power of steam, ... 33 English apparatus — Washington- Lyon's patent, ... 34 Types of disinfectors used on the Continent, .... 42 1. Austria- atus, 2. France — The Equifex stove, 3. Denmark — Reek's apparatus, 4. Germany — Schimmei's and Budenberg's apparatus, United States, Public installations, . Plan of a disinfector house, United States, 42 44 47 4S 52 52 52 5ft Chapter IV.— Chemical Disinfectants— The Non-MetallieJ Elements and their Derivatives. Halogens and their compounds. 57 Periodates, .... 75 Chlorine, 57 Organic compounds containing Chloride of lime and hypo the halogens. 76 chlorites, . 63 Chloroform, .... 76 The "Hermite" process, 67 Bromoform, .... 76 Chlorates, 69 Iodoform, .... 76 Hydrochloric acid, . 69 Ethyl iodide, . . ._ . 77 Chlorides, 70 Organic compounds containing Bromine 70 iodine 78 Iodine, .... 73 Fluorine, .... 78 Iodine trichloride, . 74 Fluorides, 79 lodates 75 CONTENTS. Chapter V— The Non-Metallic Elements and their Derivatives (continued). Oxygen, Ozone, Peroxide of hydrogen, Nitric acid and oxides of nitrogen, Nitric acid. Nitrogen trioxide, Nitrites, Nitric peroxide, Nitrous ether, Sulphur and its compounds. Sulphuretted hydrogen, . Sulphur dioxide. Sulphites, Thiocamf, Sulphur fumigation, PAGE 79 SI 84 87 87 88 89 89 90 91 93 94 94 Sulphites in food, Sulphuric acid, Sulphates, Bisulphide of carbon. Boric acid and borates. Boric acid, Borates, . Borax, Ammonium borate, Boroglyceride, Potassic borotartrate, Benzoboracic acid, . Tests for borates, Influence of gases on putrefaction Carbon dioxide. PAQB 96 97 98 98 99 99 100 100 101 101 102 102 103 104 104 Chapter VI.— Metallic Salts. Salts of the alkalies and alkaline Zinc sulphocarbolate, 113 earths, . . 106 , , salicylate, 113 Sulphate of lime. 107 Copper, 113 Carbonate of lime, . 107 Cuprous chloride, 114 Quicklime, . 107 Cuprio , , 114 Slaked lime. . 107 ,, sulphate, 115 Sodium carbonate, . . 108 Verdigris, 115 Ammonia, 109 Iron, . 116 Ammonium carbonate, . 109 Metallic iron, . 116 Zinc, .... 109 Ferrous sulphate, 118 Oxide of zinc, . . 109 Ferric sulphate. 120 Chloride of zinc, . 109 ,, chloride. 121 Zinc nitrate, . . Ill Manganese, 122 ,, sulphate, . 111 Peroxide of manganese. 122 ,, acetate, . . 113 Manganates and permanganate s, 123 ,, sulphite, . 113 Potassium permanganate, 124 :Chapter VII-Meta llic Salts (continued). Aluminium salts. . 127 Basic acetate of lead, 134 Use in sewage precipitatit >n, . 128 Mercury compounds, . 135 Aluminium chloride. . 131 Mercuric and mercurous nitrate s, 135 acetate, . 132 ,, chloride, . 135 „ sulphites. . 132 , albuminate, 141 Chromium, . 1.32 , iodide, 141 Chromic acid, . 132 , cyanide, . 142 Potassium bichromate. . 132 , zinc cyanide. 142 Arsenic, . 133 , chloroamide. 143 Arsenious acid. 133 , organic comnounds. . 143 Potassium arsenite, . . 133 Conipounds of'Various rnetals, ' . 144 Sodium arsenite, . 133 Tin — stannous chloride, . 144 Acetoarsenite of copper, Arsenious sulphide. . 133 . 134 Bismuth subgallate (dermatol). Silver nitrate, . . . . 144 144 Arsenic acid, . . 134 Osmic acid 144 Lead, .... . 134 General remarks on disinfectants. 145 Nitrate of lead, . 134 CONTENTS. Chapter VIII.— Organic Substances. Tar and its products, . PAGE . 147 Pixol, .... PAGE . 163 I. Hydrocarbons, . . 148 Pixene, .... . 163 Naphthalene, . . 148 Tricresol, . 164 Anthracene, . 148 Jeye^' disinfectant, . . 165 Petroleum, . 148 Creolin, .... . 166 II. Phenols, . . 149 Essets' fluid, . . 166 III. Basic substances. 149 Saprol, .... . 167 Phenol or carbolic acid, . 149 Izal, .... . 169 Phenol, . . 149 Europhene, 171 Carbolic powders, . . 154 Resorcinol, 171 Carbolised solution, oil, ai id gauze, 155 Pyrocatechol, . 172 Carbolic wool, . . 155 Pyrogallol, 172 Danger of phenol in surg 3ry, . 156 Wood-tar derivatives. 173 Carbolic soaps. . 156 Pyroligneous acid, . 173 Various preparations. . 156 Stockholm tar, 173 Halogen derivatives of phei lol, . 157 Retinol, .... 174 Parachlorophenol, . 157 Resol, .... 174 Tribromophenol, . 157 Wood creosote, 174 lodophenols, . . 157 Guaiacol, .... 175 Sulphuric derivatives, . 157 ,, carboxylate. 176 Sulphocarbolates, . . 158 Creosol, .... 176 Sozo-iodol, . 158 Little's soluble phenyle, . 176 Aseptol, . . 158 Naphthalene derivatives, . 177 Sozal, . 158 Naphthalene, . 177 Benzene sulphonic acid. . 159 Naphthalene-sulphonic acid. 177 Phenyl-substituted fatty acids, 159 Naphthols, 177 Cresol and the higher phenc >ls, . 160 Betol, .... 179 Creosote oils, . . 160 Microcidine, 179 Creosote, . . 161 Alumnol, .... 179 Bacillite, . . 162 Hydronaphthol, 179 Lysol, . 162 Oxynaphthoio acid, . 180 Chapter K iC.— Organic Substances [continued). Nitro-compounds, . 180 Apyonin, 187 Nitro-benzene, . 181 Furfurane, 187 Nitro-phenols, . 181 Furfurol, 187 Trinitro-phenol, . 181 Thiophene, 187 Nitro-cresol, . . 182 Pyrrol, . 188 Nitro -glycerine. . 182 lodol, 188 Nitro-cellulose, . 182 Antipyrin, 188 Amido-compounds, . 182 Pyridine group, . 189 Ammonia, . 182 Conine, . 190 Hydroxylamine, . 183 Piperine, 190 Hydrazine, . 183 Pyridine, 190 Methylamine, . . 183 Nicotine, 192 Dimethylamine, . 183 Indole 192 Trimethylamine, . 183 Tyrosine, . . . . 192 Propylamine, . . 184 Quinoline derivatives, 192 Amylamine, . 184 Quinoline, . . . . 192 Aminol, . . 184 Diaphtherin, . . . . 193 Aniline, . . 184 Oxyquinoline, . . . . 193 Acetanilides, . 185 Loretin, 193 Aniline dyes as antiseptic s, . 185 ThaUine, . . . . 193 Methyl violets. . 186 Quinine, 194 Pyoctanin, . 186 Antiseptol, 194 i CONTENTS. Chapter X.— Organic Substances (continued). PASE PAQB Benzoic acid group, . 195 Styrone . 205 Benzoic acid, . . 195 Sodium dithiosalicylate, . . 205 Listerine, . 197 Thymol, camphors, and essential Benzoic aldehyde, . 197 oils . 206 Sulphobenzoic acid, . 197 Turpentines, . . 207 Benzosol, . 197 Thymol, .... . 208 Benzo-paracresol, . 198 Listerine, . 209 Benzo-naplithol, . 198 Aristol, . 209 Salicylic acid. . 198 Menthol, . 209 Oil of wintergreen, . 199 Oil of cloves, . . 209 Salol, . 199 Oils of caraway, cinnamon, &c ., 210 Salophen, . 199 Essence of hops. . 210 Phenosalyl, . 200 Terebene, . 210 Salicylic acid as an < mtiseptic, 200 Camphor, . 2U Lactacidine, . 202 Eucalyptol, 211 Salicylic acid as a p reservative, 202 Eucalypto-resorcin, . 212 Antiseptic tablets. . 204 Myrtol, .... . 212 Salicylated gauze. . 204 Terpin hydrate, . 212 Anisic acid, . 204 Terpineol, . 212 Cinnamio acid, 204 Borneo], . . 212 Styracol, . 205 Camphoid, . 213 Phenol-propionic aci d, . 205 Oxidising power of essential oils, 213 Gallic acid, 205 Sanitas preparations, . 215 Tannin, . . 205 Pinol . 218 Chapter XI.— Compounds Related to the Alcohols. Methyl alcohol, . . 219 Pyroligneous acid, . 226 ,, chloride, . 219 Glycerine, .... . 226 Formic aldehyde. . 219 Oleic acid, .... . 227 Other aldehydes, . 223 Petroleum and paraffins. . 227 Alcohol, . 223 Vegetable acids, . 227 Formic acid. . 225 Oxalic acid, . , . , 228 Acetic acid, . 225 C hapter XII.— Pr aetieal Methods. Sanitary administratio n, . . 228 Earth-closets, . 238 Sewers and drains, 229 Pail system, . 239 Ashpits and dust-holes . 231 Privies, .... . 239 Houses, . 231 Cesspools, .... . 240 Hygienic wall-papers. . 231 Streets, .... . 241 Furniture and woodwc )rk, . 232 Wood paving. 242 Sinks, . . 232 Urinals, .... . 242 Sick rooms. . 232 Stables, pig-styes, and cowsheds 243 Isolation, . 232 Slaughter-houses, . 243 Clothing, . 232 Bakehouses, 243 Excreta, . . 233 Pigeon and fowl houses, &c. , . 243 Light and air, . . 233 Cats, . . . . . 244 After-disinfection, . 234 Vehicles, .... 244 a. Phenol, . . 234 Skins, furs, wool, hair, 244 6. Sulphurous aci( J, . . 234 Eags, 244 c. Chlorine, . . 234 Disinfection of air, . 245 d. Non-volatile di sinfectants, 235 Apparatus for sewer gas. . 246 Clothes, bedding, &c ., . . 236 Vaporisers, 246 Hospitals, . . 236 Water, .... 247 Cisterns, . 237 Preservation of timber, 250 Water-closets, . 237 CONTENTS. Chapter XIII.- Personal disinfection, . Disinfection of cavities of the body, .... 254 a. Washing out, . . 254 6. Spraying, . . . 254 c. Gargles, . . . 255 d. Injections of gases or vapours, 255 c. Inhalations, , . 256 Antiseptic dressings, . . 256 Gauzes and wools, . . 256 Antiseptic hypodermic injections, 257 Antiseptic soaps, . . . 257 Mouth washes and tooth powders, 258 Ointments, . . . .259 Respirators, . . . 259 Internal disinfection, . . 259 „ antisepsis, . . . 260 Vaccination, .... 262 Preservation of food, . . . 262 Causes of change in food, . 262 1. By oxidation, . . 262 -Personal and Internal Disinfeetion- Food Preservation. 252 PAOB 2. By reduction, . 262 3. By metallic contamination, 263 4. By organisms, . 264 Drying, ..... 265 Smoking, 265 Cold, 266 Preservation by chemicals. 267 ,, heat, 268 1. The chloride of calcium process. 269 2. The Aberdeen process. 269 3. Jones's vacuum process, . 269 4. Salzer's Baltimore process. 269 5. Budenberg's flesh steriliser. 271 6. G. Hartmann's process, . 272 7. Formaldehyde „ 272 Milk, 272 Condensed milk, 273 Butter, ... 274 Cheese, 275 Wheat— Bread, 275 Chapter XIV.— Legal Statutes and Regulations. Duties of a medical officer of health, .... -Sanitary inspectors, . Public Health Act, 1875, . Hospitals for infectious diseases, Prevention of epidemic diseases, Mortuaries, .... Port sanitary authorities, Oeneral order L. G. Board on cholera, .... Regulations as to detention. Dairies, Cowsheds, and Milkshops Order, 1885 Regulation of bakehouses, . Housing of the Working Classes Act, 1890, .... Public Health (Water) Act, 1878, Vaccination Acts, 1867, 1871, 1874, Burial regulations, Merchant Shipping Acts, 1854 to 1876, Canal Boats Acts, 1877, 1884, . Infectious Diseases (Notification) Act, 1889, .... Infectious Diseases (Prevention) Act, 1890, .... Public Health Amendment Act, 1890, Public Health (London) Act, 1891, Memorandum on hospital accom- modation, .... Memorandum on ambulances. 277 277 277 279 279 280 280 280 280 281 282 282 282 282 282 282 283 283 283 2S4 284 285 286 Rules for hospitals for infectious diseases, ..... 286 Circular of the medical officer (L. G. Board), .... 286 Suggestions of the Society of Medical Officers of Health, 288 Model bye-laws as to cleansing. &o. , 290 Model bye-laws as to nuisances and animals, .... 290 Model bye-laws as to buildings, . 290 Metropolitan Asylums' Board, 291 Legislation as to vagrants, . 291 Systems in other countries. 291 Brussels, 291 Germany (Berlin), . 292 (Leipzig), . 292 Vienna, ..... 293 Denmark, .... 293 Disinfectants, 293 Special rules for disinfection, 294 1. Discharges, .... 294 2. Privies, .... 294 3. Clothing, .... 295 4. Furniture 295 5. Rooms, &o.. 296 6, Persons attending patients. 297 7. Drinks 297 American Public Health Associa- tion, 297 Quarantine, .... 298 Italy 299 CONTENTS. Chapter XV,— Methods of Analysis, PAHE PAOK A, Bacteriological methods, 300 Examination of gases and Determination of the antiseptic vapours, . . 306 value, .... 302 Fischer and Proakauer's I. Examination of soluble method, . 306 antiseptics in solution, 302 Precautions, 302 B. Chemical methods — II. Examination of the vapours Chloride of lime. 308 of volatile fluids, 303 Sulphites and sulphurous acid. 309 III. Examination of gaseous Peroxide of hydrogen. 309 antiseptics, 303 Boric acid. 309 Determination of the germicidal Permanganate, 310 value 303 Phenol, . _ . 310 Principle of the methods, 303 Tar preparations. 311 Relative value of tests, . 304 Carbolic powders, . 312 (a) Sternberg'.'? method, 305 Salicylic acid and other preser (6) Drop 305 vatives in foods, . 314 (c) Thread 305 Medicated wools. 316 Bibliography, .... 317 Index, . 323 DISINFECTION AND DISINFECTANTS. CHAPTER T. INTRODUCTORY. Definition of Terms — Primitive Methods of Disinfecting — Bacteriology — The Methods of dealing with Bacteria by Exclusion, Removal, and Destruction. Definition of Terms. — The words "disinfectant" and "disinfection" have in recent years been used in such a variety of ways, and with such wide application, that much confusion has arisen as to the exact meaning of these terms. Before the germ theory was universally accepted, the term "disin- fection" was used to include the destruction of infectious matter and the removal of any noxious odours to which such matter gives rise. It was applied to the action of any substance which served as a mask for noxious odours, and many substances which have a powerful odour have probably become popular, as disinfectants, solely from this cause. After the germ theory had offered a plausible explanation of the origin of disease, it became possible to define a disinfectant as a germicide. Disinfection then ceased to mean simply "purification," but acquired the special meaning of "sterilisation." A true disin- fectant, therefore, must not only mask the smell, but must destroy or kill the germs which give rise to it. Many poisons have the property of killing germs as well as acting upon the higher forms of life, and could, therefore, be used as universal destroyers of life ; but, in many cases when disinfection is resorted to, it is desirable to use some agent which will discriminate between useful life and in- fectious matter. Such an ideal disinfectant should, therefore, be a substance that will kill those germs which act injuriously on the higher forms of life, without having any marked action upon such higher forms. A disinfectant must likewise be efficient in destroying the spores of pathogenic organisms, which, as a rule, are more resistant than the germs which form them. From this definition it 1 2 DISINFECTION AND DISINFECTANTS. will be seen that a disinfectant does much more than prevent decom- position, and does more than remove the noxious smells which often emanate from putrefying matter. A disinfectant really goes to the source of the trouble, and, by killing the organism, prevents the spread of epidemic disease. An antiseptic, on the other hand, prevents animal or vegetable substances from undergoing decom- position, and a body is said to be aseptic when it is in a condition of sterility. A substance which has the property of absorbing the unpleasant odours which are emitted from matter undergoing decay is called a deodorant, and such substances must be carefully distin- guished from true disinfectants. Most disinfectants are deodorants > but a deodorant, unless of a permanent character, is not an antiseptic. It is true that in most cases a noxious smell accompanies decay, and, therefore, that any substance which permanently removes the smell must necessarily cause the cessation of the decay ; but in other cases in which there is no appreciable odour, a deodorant would not be required. Charcoal is an example of a body that will absorb any unpleasant smell which may arise from organic matter, but which does not kill the germ producing the decay. Although commonly called a disinfectant, it should be more properly classified among the deodorants. Primitive Methods of Disinfecting. — Man has an instinctive repugnance to all noxious odours, and from the earliest time has sought to mask their presence by the use of aromatic substances. The use of perfumes is probably a relic of the effort of primitive man to counteract this evil. Many religious ceremonies, such as the burning of incense, have also the same origin, and embalming, as practised by the Egyptians, is a good example of successful attempts to arrest putrefaction in very early ages. Sulphur has been employed from the earliest times, and Homer describes its use in religious ceremonies. In the time of Hippocrates, sulphur was regarded as an antidote against the plague. Ovid makes mention of the fact that sulphur was employed by the shepherds of his time for bleaching fleeces and for purifying their wool from contagious diseases. During the plague of Athens, Acron, according to Plutarch, stayed the spread of the epidemic by lighting fires in the middle of the public places and in the streets where deaths had occurred ; and the lighting of fires during times of plague has been customary until quite recent times. The Mosaic law, with all its minute instructions as to the purifica- tion of the people and their belongings, shows the same combination of religious ceremonial and sanitary precautions ; this law, undoubtedly, contributed to the permanency of the Jewish race during its early history. The Indian who, instead of embalnling or burying his dead INTKODUCTOEY. 3 friend, hangs the body under a tree exposed to the air, makes use of the property of desiccation, which, as is well known, is very efficient in arresting decay, and is the basis of a modern patent for keeping yeast. Earth is a very powerful deodorant and will also act as an antiseptic ; the gases given off by decaying bodies are absorbed, and thus the burying of a body under proper conditions may be regarded as an efficient means of disinfection. The use of fire for cremating bodies undergoing decay or likely to cause a nuisance is, of course, an illustra- tion of the employment of heat for the destruction of micro-organisms. Disinfection in the Middle Ages. — During the long period of the Middle Ages, the alchemists did little to advance our knowledge of this subject ; they collected a few facts, and described, with more or less accuracy, the properties of some of the more important chemical compounds ; but one may search in vain for a correct account of any example of preventive medicine. Notwithstanding the ravages of the cholera, the plague, and other epidemics, as well as the frequency of leprosy, the idea of contagion was only imperfectly understood, and the common people were far less cleanly in their habits than the Jews, for example, or heathen nations who, as we have already mentioned, mingled primitive sanitary precautions with their religious services. Perhaps one of the earliest papers of any importance which we have is a Memoire sur les substances septiques et antiseptiques, written by Pringle in the middle of the eighteenth century. In this Memoire some forty- eight experiments are described, in which the author took pieces of fresh meat and placed them in contact with various amounts of sub- stances which Be believed to have an antiseptic action. Amongst the substances tried we find common salt, sal ammoniac, acetates of ammonia and potash, nitre, borax, alum, camphor, aloes, and succinic acid. These experiments, which were conducted in a very systematic manner, are even now not without some value. By taking as a standard the antiseptic action of 60 grains of salt on 2 grains of meat in 2 ounces of water, he was able to show that the other bodies enumerated above had a greater antiseptic power than this standard, and thus succeeded in arriving at their relative antiseptic value. Bacteriology. — Even the pioneers of modern chemistry at the begin- ning of the present century, did little towards promoting our knowledge of disinfectants, and it was not until the biologist showed that decay was due to the action of living organisms which float in the air, that fresh attention was directed to the subject. Francesco Eedi, by pro- tecting meat from flies with wire gauze, showed that the maggots which infest decaying flesh were produced from the eggs of the flies. Subsequently the formation of moulds on the surface of jams, or other oro^anic substances, was similarly shown to be determined by micro- 4 DISINFECTION AND DISINFECTANTS. organisms floating in the air. It was further noticed that infectious diseases spread more rapidly in damp warm weather when there is very little wind, and that filtration of the air through cotton wool was efiectual, not only in removing the dust, but also in preventing the ingress of micro-organisms. The gradual accumulation of such facts as these by the biologists led the chemists to realise that the removal of the odour was not, after all, the only work required to be done, and the use of fumigations with nitrous acid, hydi-ochloric acid, and chlorine and other pungent bodies, which had been recommended, fell gradually into disfavour. Pasteur's work, together with the general development of the modern science of bacteriology, has given to chemists a means of ascertaining the relative value of the various chemical substances dis- covered from time to time. It was to Pasteur's careful investigations that the close analogy which exists between fermentation and putre- faction was established. Pasteur himself defined putrefaction as " fermentation without oxygen," and showed that all decay was due to the action of organisms, the Bacterium termo being the common organism which begins eremacausis. Owing to the slight knowledge which we possess as yet of the nature of the pabulum in which these bacteria of decay live, the investigation of the way in which they act is a matter of great difficulty. In recent years, however, the life-history of known organisms has been carefully studied, and the chemical changes which are produced when they live in media of known compositions have been followed. Thus organisms have been allowed to grow in solu- tions of calcium formate and calcium acetate, both of which substances have a definite chemical constitution. The bacteria decompose these salts, evolving carbonic acid gas, mixed with hydrogen in the former solution, and carbonic acid, mixed with marsh gas in the latter. Lactic acid and its salts, butyric acid and its compounds, as well as other chemical substances of known constitution, have also in recent years been examined bacteriologically. From studies such as these it seems to be clearly established that, just in the same way as the yeast when it converts sugar into alcohol is killed by the alcohol it produces, so these other micro-organisms secrete chemical compounds which are inimical to their own life. In the decomposition of animal matter containing nitrogen, compounds which are soluble in weak alkaline solutions, and known as alkali albumens, are first jiroduced and these subsequently change into albumoses and peptones, to be again broken down into tyrosine, indol, and other compounds. These latter have strong antiseptic properties, and illustrate the fact already alluded to — viz., that the products of decomposition are in the IXTRODUCTORY. majority of cases themselves inimical to the bacteria which give rise to them. The Methods of dealing with Bacteria. — The ideal of disinfection is to stamp out the pathogenic bacteria, just as weeds are extirpated from a garden. This can never be done until their hotbeds, the filthy slums of cities and the neglected country villages, are cleansed and supplied with plenty of good water, and, in the cities, with air and, above all, light. Every dirty court or alley is an admirable culture- medium in which disease organisms may multiply ; these issuing in a variety of ways, as by clothes, food, and even sometimes by the atmosphere, may unexpectedly decimate the so-called better neighbour- hoods. There is no reason why infectious disease of all kinds should not be entirely abolished ; but it can only be done when the entire population is supplied with knowledge, and placed under conditions in which health is possible. At present it is indispensable that measures of precaution should be taken continually and habitually to prevent any outbreak rather than, as too often is the case, only spasmodically when a plague like cholera threatens. The success of improved sanitation in rendering obsolete in modern Europe such plagues as carried off millions at intervals in the Middle Ages, shows that the abolition of infectious disease is possible, but we have still among us "that sad disgrace, our customary (and preventable) autumnal epidemic of scarlatina." This would certainly yield to a vigorous and systematic insistance upon isolation and application of disinfectants. With reference to the first precaution, more and better accommodation will have to be provided. As to the second, one great reason of the want of progress has been the fact, that many of the modes of disinfection, even those prescribed by high authorities, are absolutely inefficient and useless. We must get rid, to begin with, of the idea that the creation of a rival smell is any criterion of safety ; we must cease to be misled by laudatory advertisements, and anti- quated opinions founded on inaccurate experiments before bacteriology became a science, and we must not grudge the expense of a sufficient quantity and a proper application of the disinfectants that have been proved scientifically to really effect their purpose. The problem then resolves itself into a struggle for existence between man and inimical micro-organisms, which are known to have great vitality, powers of endurance, and facilities for penetration, accompanied by a stupendous fecundity. The means at present at our disposal for dealing with this problem can be classed u.nder three heads : — 1. Exclusion. — The rough methods of . quarantine and sanitary cordons have not proved a success, since the ways of ingress are so many and wide, and the intolerable oppressiveness of these regulations 6 DISINFECTION AND DISINFECTANTS. leads certainly to their frequent evasion. The English methods of inspection, and temporary closure of certain routes, have proved much more effectual. The last, or personal, line of defence lies in the care and precautions taken by the individual. Most of these are indicated in Chap. XIII., "On Personal and Internal Disinfection." Cleanliness, fresh air, light, and good water are the chief In recent years it has also been shown that many, if not all, zymotic diseases may be excluded from the jierson by the introduction of special toxines into the individual, a process which renders him immune from the attacks of the organisms that produce the disease. These toxines are produced by the pathogenic organisms themselves, and, as already mentioned, are usually inimical to the growth of the organism, and may be regarded as their natural disinfectants. In view of these facts, Pasteur and his successors have cultivated the jjathogenic organisms in broth and other media, and after sterilisation have injected the liquid products as prophylactics against various diseases. The virus can also be attenuated by passing it through different animals, or by special methods of taming, until, whilst still producing the toxines, it can be introduced into man without pro- ducing any dangerous symptoms, and thus can render him immune from fresh attacks, or place him in a position to develop the natural disinfectant sufficiently rapidly to kill off the pathogenic organisms, even after they have gained access to the blood. Dr. Roux, for example, at the Vienna Congress in 1894, reported a large number of cures of diphtheria by injecting a quantity of serum from the veins of a horse previously inoculated with LoefHer's diphtheria bacillus. Under the name of antitoxine, this diphtheria antidote is now a commercial article, and may be regarded as a special disinfectant for dealing with the organisms of this disease. 2. Removal. — Under this heading may be included the natural pro- cesses which obtain in a healthy individual, and artificial methods for improving his environment. It is now well established that the blood by its white corpuscles, as "phagocytes," or by its enzymes, has the power of assimilating and destroying bacteria and spores that find their way into it. If vigorous health be maintained, experience proves that a human being or animal may enjoy immunity for a time, even when in an infectious area. The limit to this protection may be reached when the micro-organisms overcome the phagocytes or other defensive substances in the blood. Many natural processes, external to the indi- vidual, such as the self-purification of rivers, aid the higher organisms in this combat. Man, by artificial methods of subsidence, mechanical precipitation by inert matters, filtration, and chemical precipitation, supplements these efforts of nature to purify the water supplies.. MECHANICAL DISINFECTION. 7 3. Destruction — This is the office of real disinfectants, of which the physical agent heat is the most important. Next come the multitude of chemical disinfectants, many of which have been highly vaunted, but few of which are of actual value. A knowledge of the chemical constitution and relative position of these compounds throws con- siderable light on their mode of action ; and recent progress in synthetical organic chemistry has been of great aid in furnishing compounds of known purity and constitution, which have, at the hands of the bacteriologist, been shown to possess antiseptic and disinfectant properties of ascertained value. The number of these compounds is constantly on the increase, but at present it is difficult to predict, except in some few special cases, in what direction the constitution of a compound influences its bactericidal behaviour. It seems probable, however, that the several pathogenic organisms will be best annihilated by specific chemical compounds, so that, for personal disinfection at any rate, some of the newer compounds may eventually be proved to be definite specifics. CHAPTER II. MECHANICAL DISINPECTIOlf. Insufficiency of Deodorisation — Physical Means — Light capable of killing Bacteria — Sunlight and ordinary Daylight — Conclusions — Inert Substances : Carbon — Animal Charcoal — Vegetable Charcoal — Disinfection Gratings — Use in Closets — Peat Charcoal — Coke — Soot— Coal - dust — Peat — Sawdust — Clay — Dried Earth — Spongy Iron — Infusorial Earth or Kieselguhr — Ashes and Cinders — Gypsum — Sand Filtration : Conditions of its Efficiency — Chamber- land and Berkefeld Filters — Stone Filters — Purification of Eiver Water : Clark's Method — Gaillet and Huet's Process — Natural Purification — Desicoa^ tion : Resistance of Microbes to Drying. Insufficiency of Deodorisation.— The simple removal of smell, or even the act of disguising it by a chemical of more powerful odour, is frequently looked upon as disinfection. Yet it is obvious that the removal of the injurious products of putrefaction, although it may be of temporary benefit, will not prevent the organisms from reproducing a further quantity. There are also a number of micro-organisms known, in whose growth there is never any ill smell evolved, and no ammonia or sulphuretted hydrogen detected ; but which, at the same time, form ptomaines, and are in other ways dangerous to health. Some of these, as pointed out by Klein, may evolve an aromatic smell and thus be tolerated. 8 DISINFECTION AND DISINFECTANTS. Light as a Disinfectant. — In those cases in which it is advisable that large volumes and surfaces should be sterilised, it is not usually practicable to kill all the bacteria by chemical agents; therefore recourse must be had to their removal by physical means. L I a H T. The action of light is one of the most important of these physical agencies for diminishing the number of microbes. Downes and Blunt* first demonstrated the antagonistic action of light towards bacteria. Test tubes containing sterilised Pasteur solutions were exposed to intermittent sunlight and diffused daylight for periods varying from days to months, having been previously infected by minute quantities of liquids containing bacteria, or else exposed for a time to ordinary air. A similar set of tubes were covered completely with tin-foil to exclucje light, other conditions being the same. They found that direct sunlight in some cases entirely prevented the development of the organisms, in others only retarded it, and that even diffused daylight had a distinctly deterrent effect. The blue and violet rays of the spectrum were much more active than the red and orange. They further showed that the influence on spores was not exerted in a vacuum, that the nutritive value of the culture liquids was not affected, and that the bacteria were much more resistant when immersed in water than when sur- rounded by any other medium. From these facts they attributed the destructive effect of light to the promotion of oxidation by the influence of the sun's rays — i.e., to the so-called actinism of light. (See Chapter xiii. as to the influence of light on the rancidity of butter.) A number of other investigators continued the research with pure cultivations of pathogenic bacteria, and particularly on the production of colours by the pigment-producing bacteria. It was noticed that the sun's rays appeared to favour the development of several kinds of yeast and moulds, and that the action of light was increased by the presence of air.t Pansini J found that the destruction was rapid during the first period of exposure, 360 colonies of £. anthracis being reduced in half an hour to 4, but that the further operation proceeded much more slowly. The spores of anthrax in a dry state were more resistant to light than when moist ; in the latter case an exposure of from thirty minutes to two hours was sufficient to destroy them. * Proc. Eoy. Soc, Dec. 6, 1877. t ArloiBg and Gaillard, Influence de la Lumiere sur les Micro-org., Lyon, 1888 ; TJffelmann, Hyg. Bedeut. des Sonnenlichtes, 1889. J Rivista d'Tgiene, 1889. MECHANICAL DISINFECTION. 9 Koch says that sunlight, or even ordinary daylight, will kill tubercle bacilli in from a few minutes to live or seven days, according to the thickness of the stratum.* Janowski has also proved that four to ten hours' sunlight destroyed typhoid bacilli. After passing through a solution of potassium bichromate, so as to cut off the blue and violet portions of the spectrum, the rays had no effect. f He showed also that the effect of the light was not due to increase of temperature. Geister demonstrated that an electric light of 1,000 candle power at 1 metre distance was less effective than direct sunlight. | Mai-shall Ward§ showed that the dried spores of anthrax were acted on by light in the absence of food materials, and that the light did not appreciably diminish the nutritive value of the agar-agar medium. Khmeleosky finds that both solar and electric light inhibit the growth of Staphylococcus pyogenes aureus, Bacillus pyocyaneus, Streptococcus erisipelas, and S. p>yogenes. Sunlight destroys their vitality in about six hours, and exposure to sunlight seems to mitigate their virulence when it does not destroy them. It also makes the media less favour- able to their growth.|| Percy Frankland and other investigators have examined the action of light on the organisms in the Thames and other waters.U Buchner has also shown that in water typhoid and other cultures are destroyed by exposure to bright sunlight for three hours. By immersing cultures to different depths in the Sternberger Lake at Munich he has further demonstrated that the bactericidal action does not extend to a greater depth than three yards, and that hence in the self-purification of rivers the action from this cause is chiefly superficial. The conclusions of the various researches may be summarised to the following effect : — 1. Light has a deleterious action on bacteria in their vegetative, and, to a less extent, in their spore forms. 2. The action is not caused by the i-ise of temperature. The ultra- violet rays are the most powerful, and the infra-red the least, showing that the phenomenon is due to chemical action. 3. The effect is greatly increased by the presence of air and moisture, so much so that it is undoubtedly due to a process of oxidation, possibly brought about by the agency of ozone or peroxide of hydrogen, or both. This view is supported by experiments by Richardson,** in which it is shown that peroxide of hydrogen is formed in urine during insolation, and that the sterilising action of light can be counteracted by the addition of substances — e.g., peroxide of * Zeitschri/t fur Hygiene, vol. x., p. 285. t CentralUattf. Bahteriol., 1890, pp. 167, &e. J Ibid., 1892, vol. xi., p. 161. § Proc. Hoy. Soc, 1893, p. 310. \\.Brit. Med. Journ., 1894, p. 72. IT Ibid., 189,3, p. 20. ** Proc. Chem. Soc, 1893, p. 121. 10 DISINFECTION AND DISINFECTANTS. manganese— which destroy hydrogen peroxide.* Richardson shows that the insolation of water alone does not generate peroxide of hydrogen. Dr. Fi'ankland thinks that in the case of dried bacteria, or those suspended in pure water, the destruction is occasioned by the peroxide formed within their cells. 4. The action is not generally due to any alteration of the medium by light. 5. The result varies according to the duration of the exposure, the intensity of the light, and the nature of the organism. Anthrax spores grown at 38° C. are much more easily killed by light than those ■obtained from the same source at 18° to 20° C. 6. There is no evidence that the virulence of anthrax undergoes any permanent attenuation through exposure to light. 7. Anthrax spores are less rapidly destroyed in distilled or potable waters than in culture media, or in an isolated condition. Their ■endurance is particularly long-continued in distilled water in absence ■of air, resistance to upwards of 110 hours' exposure having been observed by Momont.f The addition of a halogen salt, such as sodium chloride, materially increases the rapidity of destruction, while an oxy-salt, like sodium sulphate, has little or no influence. 8. The effect is much diminished by the rays passing through deep layers of water. 9. Whilst every opportunity should be afforded for insolation in the ■construction of water works, undue reliance must not be placed on this any more than on any other particular bactericidal agency {Percy JFranhland). Professor Esraarch has endeavoured to make use of sunlight as a practical disinfectant for skins and furs which cannot be sterilised in a «team disinfector. He finds, however, that, as might be expected, the light has only a surface action, especially on dark materials, and that it is, therefore, valueless when micro-organisms are likely to be present in the deeper parts. MECHANICAL PURIFICATION OF GASES AND LIQUIDS. Inert substances have been used (1) for the removal of bacteria by mechanical straining or precipitation, (2) for the absorption of noxious ■emanations. Carbon. — Animal charcoal, or bone-black, more particularly absorbs substances in solution (see Filtration, p. 15). When thrown into sewage, especially with clay and other heavy powders, it carries down witli it almost the whole of the suspended matters into the sludge, and * P. Frankland, Micro-organismn in Water, 1894, p. 389. t Ann. de I'Inst. Pasteur, 1892, vol. vi , p. 21. . MECHANICAL DISINFECTION. 11 also removes sulphuretted hydrogen, ammonia, the ptomaines, and the greater part of the other organic compounds, so as to leave the supernatant liquid nearly colourless and clear. If it could be used in sufficient quantity it would be one of the best of purifiers. It also effects a slow oxidation of the matters contained in the deposit, by means of the oxygen which most forms of carbon absorb from the air. Unfortunately, it is an expensive material, as bones are in great demand for manure. A large number of processes, many patented, have endeavoured to recover the phosphate by using the sludge as a fertiliser, but they have all, so far, met with little commercial success. Vegetable charcoal has a still greater power of condensing gases within its pores. One volume of wood charcoal will absorb the following volumes of different gases : — Ammonia 90, sulphurous acid €5, sulphuretted hydrogen 55, carbon dioxide 35, carbon monoxide 9'42, oxygen 9'25. Those gases and organic vapours which are capable of oxidation, and possibly bacteria, are destroyed when they come in intimate contact, within the pores of the charcoal, with the oxygen derived from the air. The charcoal should be freshly prepared, or should be reheated to a temperature short of ignition, as it rapidly loses in power. By the latter means, or, better, by charring again in closed vessels, it can be re- vivified many times. Charcoal derived from different woods has slightly varying powers of absorption; as a general rule, the more porous it is the greater the activity. Vegetable charcoal has less action on liquids than animal, and being lighter than water floats on the surface. Letheby, Stenhouse, and others proposed the use of gratings containing wood charcoal as ventilators for buildings and sewers. They did not, however, prove a success, as they soon become exhausted. If the dead body of an animal be buried in wood charcoal it decays without putrefactive odour, except that ammonia is evolved. Wood charcoal removes the odour of all decaying matter, and has been largely employed to restore tainted meat, by placing it in the water used for boiling. Although the taint is removed, the food is not thereby rendered wholesome. It may, however, be usefully employed when only a slight change has occurred. Revill * demonstrated that charcoal is not, in a true sense, an anti- septic, since it rather hastens the decomposition of putrescible matters, although, by absorbing the products, it renders the process inodorous — i.e., it is simply a deodorant. Still it has considerable value for eess-pools, water-closets, and dead bodies, when a removal is necessary. Goddard & Co. in 1887 patented an automatic purifying closet in which a mixture of animal and wood-charcoal, under the name of "Sanitary Carbon," was discharged mechanically on the excreta at * Archives gin^r. de Mid., 1883. 12 DISINFECTION AND DISINFECTANTS. each discharge. It was said to effectually deodorise the excreta, which is true, and by retaining the ammonia, to produce a manure of some value. On shutting down the lid a sufficient quantity of the carbon is scattered over the excreta in the pan beneath at a cost for each time of using of one-eighth of a penny.* In all these methods of using carbon it is found that, as the ammonia is rather rapidly evolved on exposure to air, the substance soon becomes almost devoid of nitrogen, and has practically no value as a manure. Peat-charcoal is very light and absorbent. Its application has not been a success owing to its friability. Powdered coke, being denser, possesses much less power, yet it has been proposed in many patents for purifying sewage, either alone, or as an adjunct to other agents. As an instance, Kingzett in 1887 patented the use of a mixture of powdered coke and dry clay as a sewage precipitant. He states that the deposit can be readily pressed. Coke alone has only a mechanical action. Soot contains empyreumatic and bituminous matters in small quan- tity, and has therefore antiseptic properties due to these ingredients, but its power, though rather lasting, is not very great. It is moder- ately absorbent. In horticulture it is much used as an insecticide. Sprinkled about sewers and drains it removes the odour. Coal-dust, being scarcely porous, is almost inert. Natural bitumens have long been used for embalming, but a great part of their effect is due to the mechanical exclusion of microbes. M. de Mily has recently carried out a number of experiments on the use of bitumens mixed with chopped rags (100 kilos, of rags to 10 of bitumen for 600 vines), to prevent the attacks of Phylloxera and other pests on ground that could not be • treated with sulphur. The bituminous earth from Rhodes, which was mentioned by Strabo in 60 B.C., lias also been recently used for this purpose. The results seem to have been most satisfactory. Peat itself when dried is of value for absorbing moisture and, with it, noxious emanations. 1 lb. of it (containing 25 per cent, of water) can take up seven and a-half times its weight. 100 lbs. of powdered peat will absorb 1,438 litres of ammonia. Several patents have been taken out for incorporating it with disinfectants, for which purpose it seems at first to be admirably suited for use in stables, ikc. Ernst t proposes that peat or moss should be mixed with 2J per cent, of iron sulphate or phenol, and used for litter, privies, &c.J The odour of stables in which peat moss is employed is less than those in which straw is used as litter ; on the other hand, powdered peat is now somewhat exten- * Lancet, 1887, p. 88G. f Patent No. 2,581, 1882. t Westknight and Gall, Patent No. 11,011, 1886. MECHANICAL DISINFECTION. 13 sively used for dry. closets, and has the advantage over earth of absorbing the iirine. Schroder has also shown that it has a true disinfectant action on cholera vibrios, although other pathogenic organisms are more resistant. Drs. Frankel and Klipskin * have investigated the subject more minutely and have established the fact that the comma bacillus when mixed with peat-dust is destroyed in about three hours, whilst cholera vibrios may retain their vitality for fourteen days, unless the urine be acid. Dempster f has shown that the cholera bacillus cannot live in peaty soil. The addition of super- phosphate augments the disinfecting action of the peat, whilst kainite has little influence. The authors, therefore, strongly recommend the use of peat for isolated dry closets. Sawdust, especially the varieties derived from pine wood, is widely used, on account of the resinous and aromatic compounds it contains, which seem to ozonise the air to some extent, and also give off an agreeable odour. It is not a good vehicle for disinfectants, as it is not very absorbent, but is used to some extent in country districts where the? e is no water supply for retaining urine in urinals. Clay, blast furnace slag, shale, and dried earth are all used for special purposes. Infusorial earth; or Kieselguhr, sterilised by being subjected to a heat sufficient to cause it to glow, is said by Dr. Habart to be excellent as a dusting powder in surgery. It absorbs from five to seven times its weight of water. Mixtures of equal parts of the earth and salicylic acid, salol, or iodoform, as well as a 1 in 2,000 trituration of corrosive sublimate, have proved useful. Ashes and Cinders. — In Belgium and Holland the household ashes are thrown daily into privies and ditches with the idea of disinfection. In Salford, Oldham, and other places, the ashes, vegetable, and street refuse were formerly carbonised and iised for the same purpose, some- times with the addition of charcoal and dry earth, as recommended by Parkes. But though the odour is in great part removed for the time, and the excreta are solidified so as to facilitate removal, no true disinfection is accomplished. Gypsum with coal-tar, under the name of poudre de Come et Desneaux, was formerly much employed in France for disinfecting wounds. J Gypsum is still sometimes used in stables. Asbestos, talc, pumice, in fact any dry absorbent powder, will act nearly as well.§ » ZeiUch./. Hygiene, 1893, p. 333. t Brit. Med. Journ., May 26, 1894. J Valpeau, Cnmptes Sendus, 1860, p. 279. § Vallin, Disinfectants, pp. 41, 56. 14 DISINFECTION AND DISINFECTANTS. SAND FILTRATION. Percy Frankland * states that out of 100 micro-organisms present in. untreated river water, there were removed by the Water Companies, before distribution, in the case of the 1887. 1888. 96-7 98-4 95-3 95-3 Thames, 97-6 Lea (East London Co.), . . . 96"5 Sand filtration carefully pursued offers a remarkable and obstinate barrier to the passage of micro-organisms, and there is every justifica- tion in presuming that if disease organisms are at any time present in the raw untreated water they would be retained. This was proved by experience in the cholera epidemic at Hamburg and Altoha in 1892,t when in Altona the water was filtered carefully, in Hamburg not. Although the original water supplied to Altona was worse than that of Hamburg, the deaths in Altona were 221, in Hamburg 1,250, per 100,000. At the end of 1892 an outbreak occurred in Altona owing to a filter-bed breaking down, proving that the slightest imperfection in the manipulation is a constant menace during any epidemic. Frankel and Piefke studied the rate of filtration, J and came to the following conclusions : — 1. A filter running rapidly soon clogged, and did not properly remove bacteria. 2. The full effect was not obtained until the filter had been at least a day in use. 3. High pressure is inimical to efficiency. 4. The quicker filter actually passed less water in the course of the month than one which was originally slower, owing to the former becoming clogged. 5. Cholera and typhoid were not completely stopped, but the former organisms were more removed than the latter. 6. The slime that forms in the upper layers is the main agent in entangling the bacteria. Sterilised sand did not retain the microbes. 7. The efficiency was in all cases only relative, not absolute. Thus, mixed coarse and fine sand with fine gravel, of a depth of 3 feet 8 inches, removed 74 per cent. ; fine sand, 5 feet deep, 86 per cent., and garden earth and peat retained nearly all the micro-organisms, but the latter two in practice were too slow § to be of any practical value as filtering media. Mechanical filtration for domestic purposes can be effected by the * Micro-organisms in Water, 1894, p. 124; also Trans. San. Jnst. O. B., vol. viii., 1886. t Koch, Zeit. f. Hyg., vol. xiv., p. 393 ; vol. xv., p. 89. J Zeit.f. Hyg., 1890, vol. viii., p. 1. § Report of Massachutetls Board of Health on Purification of Sewage, 1890-93. MECHANICAL DISINFECTION. 15 Chamberland filter, or by the Berkefeld modification.. The former consists of a cylinder of biscuit or unglazed porcelain. The latter is made of compressed and baked infusorial earth ; to renew it, it is cleansed under running water, put into cold water, which is then raised to boiling, and boiled for some time. It is quicker than the Chamberland and possibly equally efficacious. If a few litres are run to waste, and it be kept in a cool place, and washed and sterilised ©very eight da3's, no bacteria will find their way through the material.* Stone filters are absolutely unreliable.! Asbestos does not long continue to retain micro-organisms, J and Drs. Sims Woodhead and Cartright Wood, in a recent report, have shown that, with the excep- tion of the filters already mentioned, there are none which are of real value. The number of bacteria per cubic centimetre (as counted under the microscope) has become one of the chief elements in valuing- the merit of a water. Spring waters have superseded river waters, and towns, which have hitherto sought water from their own rivers,, have had to seek other sources of greater bacterial purity. The principal processes of purification are : — (1) Deposition, either natural or assisted by the addition of precipitants ; (2) oxidation ; (3) the vital actions of the microbes, in which " the last word belongs to the aerobic, and, therefore, to the most inoffensive." § Clark's well-known method of softening water by the addition of slaked lime to a water, whereby nearly the whole of the carbonate of lime is precipitated, has long been known, not only to soften the water, but also to carry down the greater part of the colouring matter and suspended impurities, mineral, organic, and living. Thus at Hampton it has been found to reduce the germs in the Thames water from 1,437 per c.c. to 177. Other Methods. — Among modifications of Clark's expired patent are Gaillet and Huet's, which consists in the addition of caustic soda and accelerating the separation of calcium carbonate by deposition between plates, and Maignen's Anticalcaire, which contains more soda, sodium carbonate, and lime, and throws down nearly all the lime and magnesia, of the water. Percy Prankland, in a comparison of the original Clark's process with that of Gaillet and Huet, as tried on the water of the Colne Yalley Waterworks, found Clark, after two days subsequent rest, . Gaillet and Huet, after two hours, * Zeitschr. f. Hyrj., 1891, vol. x., pp. 145, 155; Freudenreioli, Ctnlr. f. Bahte.riol., 1892, p. 240. t Esmarch, ibid., 1892, vol. xi., p. 525. X JoUes, ibid., 1892, vol. xii., p. 596. § Duclaux, Ann. de I' Inst. Pasteur, 1894. Germs before. Germs after. Beduction per cent. .322 4 99 182 4 98 16 DISINFECTION AND DISINFECTANTS. SO that the addition of soda very greatly increases the rapidity. It must be borne in mind that even if only 2 per cent, of the organisms are left the water if^ not sterilised, but the subsequent addition of a relatively small quantity of a chemical disinfectant would secure such a result.* Slow deposition alone diminishes the number of micro- organisms present in a liquid. In the passage through two settling reservoirs of the New Eiver Co., Dr. P. Frankland found that the alteration in the number of germs present was as follows : — Germs per c.c. Entrance of first reservoir, .... 677 Exit „ .... 560 ,, of second reservoir (large one), . . . 183 Reduction only 27 per cent. Buchner t introduced into clean water in repose a number of ■difierent micro-organisms. B. pyocyaneuB multiplied abundantly, but B. typhi and B. coli (the ordinary bacillus of the intestines) died in two or three days, J whilst Percy Frankland in Thames water, and J. Parry Lawes in London sewers have noticed similar results. Duclaux concludes by affirming that putrefaction itself purifies, and the microbes themselves are. the chief purifying agents. It is true that although they finally convert putrefying matter into carbonic acid, ammonia, nitrates, and water, which are harmless, in the process several transition products are formed which are very poisonous. Moreover, if they multiply within the body they produce disease by mechanical irritation, by starving the nutrition, or by excreting toxic compounds, such as ptomaines, Ac, into the blood. It is necessary, therefore, (1) to keep their numbers within bounds, (2) to exclude or kill the specially dangerous ones, (3) in special cases, as in preservation of food, to get rid of them altogether. Such an end can be attained in the case of sewage effluents, first by accelerated deposition, second by chemical disinfection of the clarified water, and, finally, by subse- quent irrigation and filtration through land.§ Scott Moncrieff has recently proposed to utilise the micro-oro-anisms of putrefaction for destroying the sewage itself, and has patented the use of special cultivation beds for this purpose. The process has been successfully worked at Towcester, and has been tried at Aylesbury. DESICCATION. It is well known that hot warm climates are the special seats of diseases of an epidemic character, and that dry localities, whether cold or hot, are comparatively healthy. Moisture and warmth beinw * See also Kruger, Ann. de I'Inst. Pasteur, vol. ii , p. 621. j-Archiv.f. Hyfjiene, 1892, p. 184. J See also Schmidt, ih'cd.,\o\. xiii., p. 247. I Miquel, Analyse Bactiriol. des Kaux, Paris, 1891, p. 139. MECHANICAL DISINFECTION. 17 favourable to the growth of micro-organisms, it might be supposed that cold and dryness would prejudice their vitality. To a great extent this is the case. In 1871, Burdon Sanderson showed that ice- water from the purest ice contained bacteria.* lanowski proved that snow even at - 3-9 to - 16° C. contained living micro-organisms,t Schmelk found the same in snow from a glacier in Norway, J Praenkel in ice supplied from a lake near Berlin.§ Pictet has also shown that the temperature of liquid air had no germicidal action. It has thus been shown that cold alone will not kill many bacteria ; it remains to see how far desiccation is effectual against them. In sandy deserts it is common to find corpses dried and free from putrescence ; food can also be dried, and if kept protected may be preserved for an unlimited time. Herbs and vegetables are thus desiccated and ren- dered free from fermentation. Some plants, even when dried, revive when they come to a moist spot, and there are well authenticated cases of mummy wheat having germinated. Desiccation thus seems to suspend the vitality of seeds, and not to destroy it. This is true for germs ; when perfectly dry they remain for the time sterile and inoffensive, and seem to be subject to aerial oxidation ; but if, by the winds, or other agencies, they are carried in time to a moist situation, like a body of water, a plant, a human skin, or, still better, a mucous membrane (such as that of the lungs), they at once revive and com- mence to develop. The utility of the Eucalyptus and other trees in marshy districts is partly due to their absorbing and exhaling the moisture of the soil. Siccative powders, like starch and steatite, are known to be useful in surgery. Many epidemics have suddenly ceased when a dry season has set in. Both Koch and Klein have proved that the spores of most of the common species of bacteria resist drying for an indefinite period. Klein kept the spores of various potato bacilli — e.g., Peronospora infestans (the potato blight), Bacillus anthracis, the hay bacillus, and those of scurf and jequirity, in culture tubes of agar agar in a per- fectly dry state — i.e., in a closed bell-jar over oil of vitriol — until the medium had dried up to a thin shrivelled film ; and yet, even after two years and a half, on inoculating fresh materials from the above tubes, typical and good growths were obtained. On the other hand, non-spore-bearing bacteria — e.g., various species of Staphylococcus, Streptococcus — bacilli of typhoid, swine fever, swine erysipelas, Koch's * Thirteenth Report of Med. Off. of Privy Council. + Centr.f. BaUeriologie, 1888, vol. iv., p. 547. t Ibid., p. 547. %Zeitschr. f. Hyg., 1886, I., p. 302. See also Heyroth, Arbeit. Kais. Gesund., vol. iv., 1888. 2 18 DISINFECTION AND DISINFECTANTS. and Finkler's bacilli, bacilli of pneumonia, fowl enteritis, chicken cholera and grouse disease, as well as a number of others, were kept as agar cultures until the latter had well dried up. No sub-cultures could be raised from any of them. In other experiments they were dried in a current of air, or by simple exposure in a thin film on cover glasses in the manner employed by Koch, leaving them pro- tected from dust till dry. No growth of the non-sporiferous species could be obtained in gelatine. If the drying is not complete, that is if the film be too thick, so that the superficial layer forms a protective coating for the rest, then the result of inoculation with such material will be positive ; the bacteria below the surface, having been protected against drying, survive, and can produce a new crop. Similarly, when particles of solids containing bacteria are dried, it will be found that here also the centre escapes thorough drying, being protected by a superficial crust. Ordinary dust particles, however small, are never so dry that the bacteria contained in them are killed. The proof of this is that numbers of non-spore-bearing bacilli and micrococci can be cultivated from the dust of an ordinary room.* Dempster has pointed out that cholera vibrios, whilst they can survive in moist soil, quickly die when the land is dry.t Dr. Buchner .| says that in the dust of a room B. tuberculosis has been found alive a year after the patient died. But he does not believe that the virus of typhoid or other fevers ever enters the human body through the respiratory tract. Provisions that have been smoked and dried may yet contain, not only micro-organisms, but also the ova of Trichina and worms. Pemmican, the dried and powdered beef of the prairies, has been said to communicate disease. If the meat, however, has been thoroughly soaked in a preservative like pyroligneous acid, and then dried, it is usually free from danger (Koch). Dry heat and superheated steam as disinfectants will be further considered in detail in a subse- quent Chapter. * Klein, Stevenson, and Murphy's Hygiene, 1893, pp. 11, 81. t Brit. Med. Journ., March 26, 1894. t Ohio San. Record, April, 1894. DISINFECTION BY HEAT. 19 CHAPTER III. DISINPECTIOM" BY HEAT. Heat as a Disinfectant : Conditions required in a Disinfector — Modes of dealing with Condensation on Goods— Time and Steam Condition required for Dis- infection — Experiments on the Penetrating Power of Steam — Types of Disinfeotors : English, French, Danish, German, American— Public Installa- tions, English and American. Heat as a Disinfectant. — It has been found in practice tliat there are cases in -which chemical disinfection is not suitable, owing to the fact that many chemical disinfectants are very apt to cause damage to the articles treated, and also that their action frequently involves pro- longed exposure, and is even then only superficial in its effect. For instance, the usual mode of disinfecting a room which has been occupied by a person suffering from an infectious disease, is to close all outlets and burn u. given weight of sulphur therein for a period of several hours. But if this treatment be applied to such things as heavy woollen clothing its effect is practically nil, as may be readily shown by a very simple test. It has been found that a bright shilling, when exposed in a room subjected to fumigation by sulphurous acid, is immediately tarnished, but a similar coin wrapped up in a hand- kerchief or placed in the pocket is not discoloured in the slightest. It is fair to argue from this that, in the instance cited, the action of the disinfecting gases has only been superficial. The chemical treat- ment of the room is justi liable on the ground that in all probability surface disinfection only is required in dealing with substances like -wood, bricks, and iron, it having been assumed that all permeable articles, such as carpets, curtains, &c., have been previously removed for more complete treatment. It is, however, open to doubt whether, even in this case, chemical treatment would be resorted to were it practicable to apply disinfection by heat. For the reasons that have just been stated it has become usual not to attempt the disinfection of such articles as clothing, bedding, carpets, &c., by chemical means, however invaluable such means have been proved to be when applied to other cases. It would appear that the introduction of heat in some form or other for purifying purposes would be an obvious step to take, but it must be remembered that nearly two centuries ago, disease germs considered as organisms of any kind, still less as bacteria-bearing spores, -were then unknown, 20 DISINFECTION AND DISINFECTANTS. and, if their existence had even been suspected, considerable experi- mental proof would be required to show that a temperature below that at which articles of clothing would be damaged or weakened in their fibre, would be sufficient to destroy all danger of infection. The work of Needham, therefore, during and before 1743, must be looked upon with admiration, since it was he who first recorded experiments in a systematic manner involving the use of heat with the object of sterilising organic substances. His cultivations, as they would be termed to-day, were jilaced in carefully-closed vessels surrounded by fire, and his experiments led him to conclude that such treatment rendered growth impossible. Curiously enough an after-growth in the sterilised cultivating medium made him a convert to the theory of spon- taneous generation, and it was in reference to this theory, the crucial debate of the age among scientific men, tjiat the publication of his experiments was due.* Needham's great opponent, Spallanzani, in reference to the same theory, also took up the question of sterilisation by heat ; he even went so far as to detect the difference between dry and moist heat, and showed that in some instances animal life was impossible in water at 45° 0., whereas the same cultivations were not destroyed by dry heat at a temperature less than 80° C. In 1804, Appert discovered that meat, vegetables, &c., when placed in carefully sealed receptacles, and dipped in boiling water for an hour, would keep indefinitely without putrefaction or fermentation. This process was very carefully reported on by Gay Lussac (at the request of the French Government), who, owing to these investigations, expressed the opinion that no oxygen was present in the sealed vessels after the process, and that the absence of this gas was essential to the preservation of animal or vegetable tissue; but it was noteworthy that, although this hrochure was for long regarded as the standard work dealing with the subject, no mention whatever was made of the destruction of germ life within the vessel. It is generally believed, however, that the earliest application of heat to disinfection on a large scale, as opposed to the laboratory experiments of Needham, Spallanzani, &c., was not made public until Dr. Henry, F.RS., of Manchester, gave an account in the Philosophical Magazine for 1831 of some experiments he had made on the disinfection of infected clothing by hot air. A steam jacketted copper was used into the casing of which only steam at 212° F. was admitted • but apparently, it was found impossible to heat the interior to much more than 200° F. with these appliances. Dr. Henry's results, so tar as they went, were encouraging, and tended to show that the clothin" of * See La fj^niration sponianie, by I. Strauss ; Jrch. de midecine expirimentale, t. 1=', pp. 139-156 and 329-348. DISINFECTION BY HEAT. 21 scarlet fever patients, -which had been submitted to a temperature of 200° F. for two to four hours, would not propagate the disease if worn by other healthy persons. Most of Dr. Henry's experiments, and even of those of Dr. Baxter in 1875, were made with vaccine lymph, and it was really not until the experiments of Pasteur, Lister, Burdon Sanderson, Tyndall, and Koch had been published, that sufficient data concerning the reality and nature of bacteria existed to render it possible to test the efficacy of heat, dry or moist, as a destructive agent. The results of Tyndali's experiments (communicated to the Royal Society in 1876 and 1877, and also contained in his well-known book, entitled Floating Matter of the Air) were remarkable, inasmuch as they treated the subject lar'gely from the physicist's standpoint. In this work he proves conclusively how very variable is the treatment, both as regards duration and intensity, of the heat essential for the sterilisation of organic matter. He showed, for example, that hay infusion might be kept continuously boiling for several hours and yet not be sterilised, inasmuch as the spores could resist such treatment and develop subsequently, although the original mature bacilli would have all been destroyed. As a proof of this he boiled similar infusions intermittently for a couple of minutes, twice or three times during a day or so, and found that, although the total period of actual boiling might be less than six minutes, compared with the hoiirs of the previous case, no aftergrowth whatever appeared in the preparation. Tyndall also pointed out, and proved in some cases, that oxygen was an essential to the existence of micro-organisms. He found that 180 minutes continuous boiling failed to sterilise a turnip infusion in the presence of the ordinary supply of air, but that ten minutes at 212° F. sufficed to produce absolute barrenness, when such heating was con- ducted in absence of air. The production of a vacuum was found to be such an important factor in sterilisation that experiments were made to ascertain whether the total absence of oxygen would in itself be sufficient to effect destruction, and in so many instances was this found to be correct, that the conclusion was arrived at that, with suffi- ciently perfect exhaustion, all infusions would probably be sterilised.* The views of Tyndall, in reference to the necessity of oxygen for the propagation of microbes, have since been much modified by the experiments of later observers, who discovered that a small class of bacteria, called " obligatory anaerobes," could only exist in the absence of oxygen, and that others, " facultative anaerobes," increased most in the presence of free oxygen, although it was possible for them to exist in the absence of this gas. The latter class is the larger of the two, and * Comples Bendus, vol. Ixxx., p. 1579. 22 DISINFECTION AND DISINFECTANTS. includes many pathogenic organisms, such as the bacillus anthracis, and the bacillus of Asiatic cholera. There is also a third class, " obligatory asrobes," to which the presence of oxygen is an absolute necessity. The observations of Tyndall are, in this respect, not per- fectly accurate, although it is probable that his conclusions would hold true for the larger number of cases for which disinfection is required, insomuch as clothing is constantly aerated, and, therefore, should, under ordinary conditions, contain no living obligatory anaerobes. The foregoing results are of the greatest importance from the prac- tical standpoint, as will be seen later on. They paved the way for further progress at the hands of Koch, Pasteur, and others.* Koch made his experiments on pure cultivations of (1) non-spore-bearing organisms, such as the Micrococcus prodigiosus ; and (2) of spore- bearing kinds, such as anthrax bacilli, &c. He attempted disinfection by chemical agency, hot dry air, and by steam ; moreover, in all these cases the trials were eventually made on a sufficiently large scale, with bedding, &c., to make his results of the greatest value. He confirmed, generally, the result of previous workers that the spores were the most difficult to destroy, and that, therefore, if they be devitalised, all bacteria will also have been rendered harmless. In dealing with hot air he found that spores were only destroyed by being exposed at 284° F. for a period of three hours, but that at this temperature t almost all fabrics which require disinfection are already injured, and that the rise in temperature inside a small roll of blankets so exposed was not sufficient, unless the exposure was continued for a much longer period. When steam at 212° F. was used as a disinfect- ing agent, Koch found that anthrax spores, when freely exposed, were killed in five minutes, and that even with steam at atmospheric pres- sure, penetration of heat through blankets took place in about one- quarter of the time necessary to secure a sufficient internal temperature when hot air alone was used. From the medical point of view, these experiments were most satisfactory, although, owing to the crude nature of the apparatus used, it would appear that most, if not all, the articles treated were considerably moistened and in some cases damaged by the action of the steam. Hoch and Wolf hiigel | conclude that " dry heat, even continued for two hours at 150° 0., did not always assure disinfection, although nothing resisted, even for a few minutes, boiling water or steam at 100° 0." Gaffky and Lbffler§ summarise their experiments as follows : — * Mittheilungen aus dem K. Ge^undheitsamte,- vol. i., p. 188. + See also Brit. Med. Journ., September fj, 1873. X Mitt. <.L. d. Kais. Gesundh., 1881, p. 301. § Ibid., p. 322. DISIIfFECTIOIf BY HEAT. ^3 1. Non-spore-bearing bacteria cannot endure for one and a-half hours an exposure to hot air at 100° C. 2. The spores of mould are not killed by one and a-half hours exposure to hot air at 110° to 115° C. 3. The spores of bacilli are only killed by three hours exposure to hot air at 140° 0. Bonhoff and Foster * state that Bacillus tuberculosis at 60° C. dies in one hour, at 90° C. in five minutes, and at 95° C. in one minute. The experiments of Dr. Klein and Dr. Parsons, as detailed in the Annual Report to the Local Government Board for 1884, confirm very largely those of Koch, and they also deal with the question of practical disinfection in a manner that renders this work of very great value. The great advantages of steam over hot air were demonstrated very clearly, and, owing to the number and diversity of their experiments, they were able to show that, in some cases at all events, the action of steam in a suitable apparatus was not in itself injurious to the articles treated. The work of Pasteur, Tyndall, Lister, Koch, Parsons, and others has, therefore, determined the fundamental conditions for successful disinfection by heat. Conditions required in a Disinfector. — It remains to be shown that the mechanic can meet the requirements of the bacteriologists, and, at the same time, deal with the practical difiiculties that invariably beset him during the introduction of novel machinery. The conditions for dry-heat disinfection, so far as temperature and duration of exposure are concerned, have not been very clearly defined ; but from experi- ence gained by Dr. Hopwood at the London Fever Hospital, it maybe gathered that an exposure of bedding to hot air at a temperature of 250°^ F. for a period of nine hours is generally sufficient, and no material damage is caused thereby to the goods. The great difficulty in designing a stove to fulfil these conditions arises from the fact that it is almost impossible to obtain a uniform equable temperature in a sufficiently large chamber. It is probable that exposure to air at a temperature of 260° F. for nine hours weakens many woollen materials, and a temperature of 280° F. distinctly dis- colours them, whereas an error of 10° or 20° F. on the lower side of 250° F. renders disinfection by these means more doubtful. The allowable range of temperature in a hot-air disinfector should, there- fore, not exceed 20° F., and the mean should be about 250° F., since, according to Drs. Parsons and Klein, the free exposure of anthrax spores to air at 245° F. for one hour suffices for their destruction. Most engineers are well acquainted with the great difficulty met * //y?.. Riivd'udian, vol. ii., p. S69. 24 DISINFECTION AND DISINFECTANTS. ■with in heating air to a uniform temperature, and the problem is not made any the easier by the fact that in such places where hot-air machines are now required, steam is not available for heating the air. If it were available, there can be little doubt but that it would be employed for the actual disinfection without the aid of air. As a rule, coal and gas are the only sources of heat available for the pur- pose, and even then, seeing that it is merely in the smallest and most out of the way districts that hot-air disinfectors are permissible, the; first cost of the apparatus has to be kept so low that adequate tem- perature regulating becomes almost impossible to provide for in a chamber of the requisite size. It must be remembered that although local conditions may make it excusable to erect hot-air apparatus, the size of the hospital or population of a district does not determine the capacity of the hot chamber, for it must be large enough to contairt the largest article that it is likely to have to disinfect (usually a double mattress) without being folded. In dealing with hot-air disinfection it becomes especially important to arrange the articles in such a manner as to reduce to a minimum the distance through which heat has to penetrate, and, therefore, bulky things, such as mattresses, should never be folded, and if several have to be treated at once, each should be separated from its neighbour by wooden strips to allow of 2-inch or 3-inch air space. Seeing that mattresses should not be folded, owing to the diminution in penetrative effect of the heat, and frequently cannot be folded or bent without damaging their construction, we can at once fix upon a length of 6 feet as a minimum for the chamber, or if this be not practicable, the diagonal should not be less than this, if, as is generally possible in a hot-air chamber, a rectangular section can be used. One dimension being fixed at 6 feet as a minimum, another may be deter- mined in a similar manner by the width of the mattress. In hospitals or public institutions beds do not commonly exceed 3 feet in width, but private household mattresses very commonly exceed 5 feet. It may, however, be assumed that in the future no public hot-air dis- infectors will be erected, and that their very limited scope will be confined to small workhouses or institutions ; hence, after allowing for a small margin, a depth of 4 feet should suffice. The depth and length being fixed respectively at 4 feet and 6 feet, the width may be fixed according to circumstances depending on the number of mattresses or clothes likely to require disinfection at one time. Thus four mattresses each 6 inches thick would require a chamber 3 feet 6 inches wide, after making sufficient provision for air space between each unit. As a matter of fact the smallest really satisfactory hot - air disinfectino- chamber usually erected in this country is 4 feet 6 inches long, 4 feet DISINFECTION BY HEAT. 25 6 inches high, 4 feet 6 inches wide internally, and in this an ordinary 3 feet X 6 feet mattress must be placed diagonally. This is a very unsatisfactory arrangement, owing to the available space being so much cut up, and also because the ends of the mattress rest actually in the angles of the chamber where it has been ascertained a certain quantity of "dead" air (i.e., unchanged or stationary air) generally remains at a temperature considerably lower than the average throughout the closet. The latter objection is in reality one common to most dis- infectors of rectangular section, but if the chamber be of ample size, these dead air spaces need not actually be occupied by portions of the charge. The question of air circulation through the chamber is probably one of very great importance, for not only does it tend to promote uniformity of temperature by admixture of gases of different tempera- tures, but also it has been found that gases in motion can be more readily heated by n hot surface owing to their rubbing action, and conversely, that moving heated gases can part with their heat more readily to cold surfaces than when they are at rest. In all hot-air stoves there is, of course, a certain risk of overheating the goods, and in most cases they are temporarily weakened, and perhaps rendered brittle, immediately after their removal, although these latter defects usually disappear after the articles have regained their normal hygrometric moisture; possibly this does not occur in such disinfectors. as have water pans exposed in the hot chambers. Precautions have also to be taken to damp a fire in the chamber should it occur, owing to the presence of kicifer matches, in spite of the fact that a careful attendant can always search for and remove all such dangers from the pockets and linings of garments, &c. The danger against fire is very usually guarded against by placing some fusible links in a chain stretched across the interior of the chamber, which chain is so con- nected to a damper that when broken, the latter closes the exit to the chamber, and thus the fire is automatically gradually quenched through lack of oxygen. The same device is also commonly geared to close the gas supply, if it be a gas-heated machine ; but it must be noted the arrangement is one which only comes into action after the evil has arisen, and does not protect clothing from damage, but merely checks- the extension of fire. Dry-heat machines are likely to be little used in the future, and it is, therefore, unnecessary to describe them at any length. Dr. Parsons' Report of 1884 gives full particulars of the several types then in use. Dr. Parsons found that very few, if any, fulfilled all the conditions required for adequate disinfection, although he mentions Bradford's apparatus as being the best coal-fired dis- infector, and the invention of Dr. Ransom as being a very suitable 26 DISINFECriON AND DISINFECTAKTS. gas-lieated machine. The former contained an exposed dish of water during Dr. Parsons' experiments, wliereas the latter did not; although there is no appai-ent reason why such an addition should not be made if found advantageous. In the Bradford apparatus, a range of temperature of 24° F. was found to exist throughout the chamber, the maximum being about 248° F. The moistening of the air was found to have an appreciable effect in aiding the penetration of the heat, and thus diminishing the period of exposure, and in Mr. Bradford's opinion it also tended to preserve fabrics from injury at high temperatures. *W!v mw s n^',-. '■== 1 I r- ii / f fevMJ 111 -r- J _ *< ^- ftyv -"I" I """'"" Fig. 1.— Bradford's Hot-Air Disinfecting Apparatus. On the other hand, it is clearly difficult to so stoke a fire as to produce a uniform temperature in a large chamber (even opening the furnace door caused a drop of temperature in the chamber of 7° F.), and the success, or otherwise, of the process must, therefore, largely depend upon the skill and attention over several hours of the person in charge. No experiments appear to have been made with microbes in either machine, so no definite proof is given that moist air at about 230° F. has absolute germicidal properties, if continued for two hours only. The construction of one form of this plant is given in Fi<^. 1. In Dr. DISINFECTION BY HEAT. 27 Eansom's apparatus, which is heated by gas, the temperature may be ^;Utoinatically governed by means of the now well-known mercurial regulator, and on trial a variation of 9° F. was recorded in the chamber, the minimum being 247° P. Although the time taken to get up the requisite temperature and disinfect is considerable, the apparatus can be left with safety to work without attention owing to the gas regulator, and, in consequence, the drawback is much minimised. In this case also, a constant stream of heated air passes through the machine, which, no doubt, tends to preserve uniformity of temperature, and perhaps accounts to some extent for the better results than can be obtained in a coal-fired apparatus. The chief drawbacks to hot-air disinfection are, therefore, due to the slowness, and the danger of damaging the goods. It has also been found that the process offers facilities, or even encouragement, to the man in charge to scamp his work, for one can rarely tell by the appearance that articles have been disinfected or not, and so great is the risk of articles firing or being singed, if subject to a temperature of 250° F. for several hours, and thus bringing the attendant into trouble, that, as often as not, he takes the precaution never to allow it to exceed 200° F. In one instance, at a dry -heat disinfecting station in a densely populated London district, the attendant actually prevented the air rising above 190° F. because expenses have been incurred in the past for the replacing of damaged clothing. This farce has been going on for many years, and had not been altered in 1894. Such a state of things would be almost impossible if steam were usedj and, moreover, there exists no such temptation, for there is no danger of damaging the clothing by heat in a well-constructed steam apparatus, and the required temperature is obtained independently of the attendant after his steam valve has once been opened. The superior germicidal and penetrative qualities of steam have already been referred to, and the only drawback to its adoption is that, unless proper precautions are taken, the steam may condense on the articles in sufficient quantities to damage them, and to necessitate drying subsequent to their removal from the machine.* Modes of Dealing with Condensation. — This question of condensation roughly divides the several types of steam disinfecting apparatus into two ■classes, viz., firstly, those in which provision is made to prevent copious condensation by keeping the walls of the chamber at a higher tempera- ture than the steam inside ; and, secondly, those in which no such provision is made, and which frequently necessitate, as a consequence, the subsequent drying of goods. Each of these classes might be * See V. Esmarch, Zeitsch.f. JIyg:,'Bil. iv. ; Gniber, GesundJieits ingenieur, 1888; SmAAb,. Archav. f. Hyg.r'B^- ix. 28 DISINFECTION AND DISINFECTANTS. further subdivided into several others determined by the pressure of the steam admitted to the chamber, by the currency or otherwise of the steam in contact with goods, and by the introduction or addition of apparatus necessary to create a vacuum in the chamber. Special apparatus has also from time to time been made to overcome special difficulties, such as arise when heavy bales of rags or merchandise have to be treated in large quantities. The usual practice at home is to erect a machine in which condensation is prevented by means of a steam jacket or outer casing surrounding the chamber containing the articles to be treated, and into which steam is admitted at a higher temperature than that passing subsequently into the chamber. The walls of the chamber being retained thereby at a higher temperature than the steam admitted, condensation of the latter, due to contact with cold walls, is absolutely prevented; but it must be borne in mind that however valuable Washington Lyon's invention may be, it does not absolutely prevent condensation on the goods themselves, which are cold when first admitted, and only slightly warmed on the surface by radiation from the hot sides and air convection due to the same cause. There is, therefore, an initial condensation on the surface of most goods when first brought into contact with steam, and consequently a rise in temperature owing to the reception of the latent heat of the steam during liquefaction. The fresh steam which next comes into contact with the goods does not condense so largely, because they are at a higher temperature than before; but, nevertheless, liquefaction does occur, and the articles again rise in temperature. This cycle of operations repeats itself again and again rapidly, but finally the whole of the articles are at the same temperature as the surroundino- steam and no further condensation occurs. The influence of the jacket then becomes of greater importance, for it heats the steam, and no steam is being condensed. The consequence is that the steam becomes super- heated (the safety and reducing valves keep the pressure constant) and is always kept in circulation by the convective effect of the sides ; the result is that whatever moisture the goods may hold is re-evaporated, so that they may be taken out substantially dry. It would appear perhaps, from the foregoing description that many delicate fabrics would be damaged by even the temporary condensation at the com- mencement of the process; but it is found in practice that surprisingly little injury is done ; even the colours in clieap cotton print show no signs of running, while delicately-linted silk dresses are but little affected by the condensation. Some materials lose their gloss, and certain other woollen goods, such as new blankets, take the slightly yellow tinge that would generally follow a good washing ; the only goods which are absolutely damaged are those made of leather or fur. DISINFECTION BY HEAT. 2& These latter should always be treated by dry heat, or other means, and the same remark generally applies to varnished or glued wood- work, although heat of either sort when applied to finished woodwork almost invariably leaves a record of its application of a more or less serious nature. Time and Steam Conditions required for Disinfection. — The precise time required for disinfection in such a machine as has just been described depends on three main factors — viz., firstly, on the particular disease germ that it is required to kill ; secondly, on the nature and bulk of the articles supposed to contain the germs ; and lastly, on the steam pressure employed to secure penetration into the goods. It is, of course, impossible to say whether any article contains only one species of microbe, and also it is very frequently found to be practically advantageous to treat at one operation the clothing, &c., of patients suffering from several distinct maladies. As it also simplifies the routine work of the attendant to have only one basis on which he may calculate the total time required for disinfection, the minimum time generally adopted should be that required for the steam to kill the most persistent microbe when unprotected by foreign and artificial surroundings. According to Dr. Klein and others anthrax spores have hitherto been found to be among the more persistent forms of organism affecting human beings, and, judging from their experiments, it may be said that a free exposure to saturated steam, at 212° F. for fifteen minutes, was a period in which sterilisation could be effected with certainty. It was found that five minutes exposure under the same conditions gave doubtful results, and, therefore, it is probable that absolutely safe disinfection cannot be efiected with steam under less than ten minutes free exposure. This period was also found just sufficient to kill lice and their eggs, for which purpose these machines are sometimes almost entirely used in such places as workhouses. The germicidal effect of saturated steam at a higher pressure of, say, 15 or 20 lbs. per square inch is usually supposed to be greater than that of steam at atmospheric pressure ; in fact. Dr. Klein considered that its efficacy might be taken for granted, and, therefore, made no experi- ments of a similar nature by its aid. There is, however, one point to which attention should be drawn ; steam may be either " saturated " or " superheated," but the germicidal influence of the two is considered by many to be different, although the steam is dry in both conditions, and either form may exist at any pressure or in the absence of water. These two facts are mentioned, because in the minds of some saturated steam is commonly associated with moisture, and superheated steam is confused with steam under pressure. The two forms are distinguished entirely by their temperature — that is to say, steam may just exist at 30 DISINFECTION AND DISINFECTANTS. 227-95° P, under an absolute pressure of 20 lbs. per square inch (i.e., including atmospheric pressure), or by adding more heat to it, its temperature will rise, say, to 300° F, at the same pressure although its volume will increase, and in this condition it is said to be super- heated. In most, if not all, steam-jacketted machines the earlier portions of the operation must perforce be conducted with saturated steam, and in the better machines, from which the articles come out absolutely dry, it is probable that the steam contained in the chamber becomes slightly superheated towards the end of the process. Hence, it matters but little in a jacketted machine whether saturated or superheated steam be the better disinfecting agent, for steam may be used in both conditions. As a matter of fact, the diiSculty has always been to bring the articles out dry, and so long as they come out with even i per cent, added moisture, it is certain that the steam has never been entirely superheated. The question of steam pressure to be employed is one which has been much debated, and at the present time there are machines (mainly on the Continent) which employ steam at IJ lbs. pressure ; and others again working with steam at 20 lbs. pressure. Assuming, for the sake of argument, that the higher pressure steam has no greater germicidal effect than the lower (which is not probable), it still has many im- portant practical advantages which are of great value in most cases. When bulky articles, such as mattresses, rolls of carpets, &c., have to be treated, or when the machine must be filled so entirely that the air space between each article almost disappears, then it is clear that penetration of 20 lbs. steam will take place far more rapidly than if this pressure be only 1 or 2 lbs. Or, again, a machine which uses steam at 20 lbs. pressure may be worked off almost any existing boiler, because almost all steam generators nowadays work at pressures above that required, and, although it is a comparatively simple matter to reduce the pressure automatically to 20 lbs., it is not nearly such an easy problem to reduce the pressure sufficiently so that the steam may be used with safety in apparatus designed to stand IJ lbs. only. This difficulty may entail the erection of a special boiler of unusual design, and steam is then raised under conditions the reverse of economical. It is also noteworthy that condensation is more likely to take place when low-pressure steam is used than when steam at a higher tempera- ture is admitted. The main objection to high-pressure apparatus is that the machines require not only greater strength, but also more careful design, and are consequently more costly. There are occasions, doubtless, when, on economical grounds only, the low-pressure machine is allowable ; but the circumstances, even in these cases, should be such that time for drying articles can always be allowed subsequent BISISPECTION BY HEAT. 31 to treatment. Although steam can, as has already been shown, pene- trate the bulkiest article in a comparatively short time, this period ™^yi by ^ little manipulation on the part of the attendant, be very materially reduced. In arranging the goods in the chamber, every care should be taken to leave a little space between each of the various rolls or bundles. Often a few pieces of wood or a rough hurdle may come in very useful when articles have to be piled one on the other^ or things can be hung up readily so as to allow of circulation. In all cases it is safest not to permit the attendant to handle infected articles more than is absolutely necessary ; therefore, bundles or rolls ought. not to be themselves unpacked, although such a proceeding would undoubtedly hasten the process. Again, after the chamber has been closed (assuming it to contain bulky articles), penetration may be greatly facilitated by relaxing the pressure and refilling several times during the process. Thus, if the chamber be filled with steam at 20 lbs. pressure in two minutes, this steani may be allowed to remain stagnant for say two minutes, and then allowed to escape. It should immediately be refilled with steam, and perhaps five minutes later again allowed to escape, and so on. It is probable that this procedure- is advantageous owing to the large amount of air retained in woollen and. other goods, which is compressed by the steam into their centre, and if not allowed to distribute itself throughout the chamber by removal of pressure, would greatly retard penetration. It has been found that rolls of blankets, rolls of carpels, and compressed bales are among the most difficult articles to disinfect, and in such cases the precautions just referred to should most certainly be adopted. Mattresses and pillows can readily be separated one from another, but- if this be not done, considerable time may be required for these also. There is still one difficulty which arises when heavy charges are placed in the machine, and that is due to the internal condensation in the centre of the goods. The explanation of the causes promoting con- densation will have made it clear that such difficulties will be more difficult to eradicate in large bundles than in small ones ; and, as a matter of fact, it is generally the rule that moisture will he perceptible in the centre of a large roll in spite of the steam jacket. It is clear that condensation may be entirely avoided in the first place if the goods be raised to tlie temperature of the incoming steam prior to its admission j but it has been shown that in dry-heat stoves it is a very lengthy operation if the goods be bulky. The length of time is due very largely to the fact that the hot air is not forced into the centre of the goods ; in fact, it has little more than a surface action, and, as a consequence, the goods usually act as a capital non-conductor to protect the interior, and the cold air retained there. But if we assume that 32 DISINFECTION AND DISINFECTANTS. this contained cold air could be withdrawn, and the hot air subse- quently forced in to take its place, we get a very diiferent state of things, and the heating can obviously be eifected far more rapidly. This course is practicable if steam be available, for the removal of air and the compulsory substitution of other heated air absorbs more work than could be expected from an attendant if steam power were not at hand, as is the case when dry-heat disinfectors are employed. The whole process may be completed by merely creating a vacuum in the chamber and then admitting heated air at atmospheric pressure. It is a very simple matter to withdraw the bulk of the air by a simple steam jet arranged after the fashion of the ordinary spray producer until a vacuum of 20 inches is indicated on the gauge ; and then, if the chamber be placed in communication with the atmosphere, air is forced in at a pressure of about 10 lbs. to the square inch, and, in transit, it may be passed through a short coil of pipe surrounded by Bteam at the required temperature so as to heat it to the most suitable degree. There are many features about this process to recommend it ; for, not only is it possible to regulate the temperature of the incoming air to a nicety, but it is also itself easy to heat, because it is constantly in motion, and, for the same reason, the hot air itself heats the goods it comes in contact with the more rapidly. If the air be passed through pipes heated by the direct heat of a fire, it becomes almost impossible to control its temperature, and the same dangers of scorching arise as were found by the use of dry heat stoves. In the class of apparatus described it has been found desirable to keep the temperature of the incoming air to about 220° F., so that, when steam is admitted at 250° F., it does not become superheated, and its germicidal influence is not aifected. Supposing, for the sake of argument, that moisture -still remains in goods after steaming, the presence of the vacuum and hot-air apparatus is still of great value ; for by its aid the articles may be dried to any extent desirable at a far lower temperature than 1212° F. The vacuum has several other advantages quite apart from its drying qualities. It enables the operator to remove most of the air from the chamber before the admission of steam ; consequently, the ordinary steam pressure gauge may be read accurately as a temperature gauge, seeing that the mixture of steam and air has not to be considered, whereas the temperature of saturated steam varies with its pressure. Also, the production of a good vacuum * prior to the admission of * The term vacuu7n is not intended to impljf the total absence of gases ; a space filled with a gas, and under a pressure equal to that of 20 inches mercury as measured by the vacuum gauge, would be generally referred to as a fairly good vacuum. DISINFECTION BY HEAT. 33 steam is equivalent to raising its pressure, so far as its penetrative power is concerned; consequently, the rapidity with which bulky articles are disinfected is very much increased, although the tem- perature at which they are treated remains unaltered. It thus becomes possible to disinfect goods with steam, at only 10 lbs. pressure as rapidly as with steam at 20 lbs. pressure, when no vacuum is created. Both these points are of importance, since of late years the practice has become prevalent to treat very bulky things, such as rolls of carpets, compressed bales, (fee, and as the amount of work to be done is thus much increased the disinfecting chamber is commonly packed closely. Moreover, the damage done to delicate fabrics, which sometimes lose their gloss at 250° F., may be entirely avoided by disinfecting at say 220 F., without any increase in the time required to secure penetra- tion. Altogether, the advantages to be gained by the introduction of this inexpensive and simple vacuum apparatus are considerable, and great credit is due to the inventors (Mr. J. B. Alliott and Mr. J. M. C. Baton). Experiments on the Penetrating Power of Steam. — An idea of its powers may be gathered from a comparison of the following two trials. In p. 296 of Dr. Barson's report it is stated that a cotton rag press- packed bale was tested in a Washington-Lyon machine. The dimen- sions of the bale were 3 feet 6 inches x 3 feet ^ 2 feet 3 inches, and its weight was 5 cwts. At the end of four hours a thermometer at its centre registered 258° F., and the increase in weight was 4'8 per cent. Experiments were made in 1893 with a similar machine, but fitted with the vacuum apparatus, on a press-packed bale of cotton rags weighing 5 cwts. 3 qrs. 13 lbs., and measuring 3 feet x 2 feet 4 inches X 4 feet 6 inches. The trial was conducted on similar lines, and every precaution was taken to prevent the passage of steam down the hole through which the thermometer had been admitted by plugging it up with a long conical piece of wood larger in diameter than the hole itself. The thermometer was so arranged that when the mer- cury column reached a height equivalent to 220° F., an electric bell was rung outside the chamber. The bell rang precisely forty-five minutes after the introduction of the bale to the chamber, and it was removed after a final drying by the vacuum and hot air after a further period of thirty-three minutes. The whole time taken was seventy- eight minutes, and the total increase in weight was less than 2-6 per cent. The bale was again submitted to the air-drying for fifteen minutes, with the result that the moisture was further reduced by 30 per cent. S The accompanying chart shows the mode of working adopted during this trial, although it would probably have hastened the process had 34 DISINFECTION AND DISINFECTANTS. the alterations of pressure and vacuum been more frequent, and it was also a mistake to have admitted the steam immediately on obtaining the first vacuum, instead of admitting and extracting hot air prior to the admission of the steam. The particular trials referred to are not such as will have to be frequently repeated in public disinfecting stations, but they have been given merely as indicative of the greater penetrative and drying powers of jacketted disinfectors when fitted with vacuum apparatus. If bedding or clothing has to be treated the Fig. 2. — Chart showing effect of vacuum of apparatus on the penetrative power of steam. duration of the process is considerably shorter in either form of apparatus ; but there still remains the same advantages in favour of the machine fitted with the vacuum apparatus. English Apparatus — Washington-Lyon's Patent. — In this country the machines mostly in use are those made under Washington-Lyon's patent. This is largely owing to the far reaching nature of Mr. Lyon's specification, on which much litigation has taken place. Generally speaking, these machines are made in two forms, square and oval in section. The square form (until recently known as Goddard's patent, made by Goddard, Massey, & Warner, of Nottingham) is jacketted all round the body, in addition to the two doors. The jacket in this case is usually half filled with water, and is used as a boiler. The fire- grate is placed immediately under the body of the machine, and the firebrick flue (see Figs. 3 and 4) is built to traverse the bottom, and thence along other flues, built around the sides of the machine, to the ohimney. The steam pressure in the jacket {i.e., the boiler) is usually limited to 20 lbs., and disinfection is carried on by steam at the same and lower pressures. Arrangements are also provided for passing a current of hot air through the chamber before and after disinfection. The air is heated by passing it through a pipe situated in the furnace DISINFECTION BY HEAT. 35 flue immediately under the disinfector, and thence into the chamber. The air may be circulated and extracted from the chamber by means of a small exhauster. This apparatus has had a considerable sale owing largely to its rectangular form, and there can be little doubt that it disinfects adequately, and also that when properly worked there should be little or no moisture present in the goods subsequent to disinfection. Its apparent first cost is also a factor in its favour, although if the cost of the necessary brickwork setting and side flues be added to the cost of machine and erection, this advantage is more Pig. 3. — Sectional plan of Goddard Sc, Co.'s square form of Washington- Lyon's disinfecting chamber. apparent than real. Its chief disadvantages are, curiously enough, precisely due to those features which are presumably advantageous. For instance, the square shape is to some an attraction, whereas it is undoubtedly a constructive weakness, and for obvious reasons the most suitable section for a steam chamber to stand a considerable internal pressure would be circular. Tims this advantage has to be paid for in the shape of repairs to leaky joints, insurance, &c., although possibly, in certain cases, it may be worth the risk. Again, the use of the jacket as the boiler is advantageous inasmuch as less space is required ; but, on the other hand, it is an imperfect boiler, which cannot be got at properly for cleansing, and is likely to be the cause of 36 DISINFECTION ANIJ DISINFECTANTS. mishaps, especially at the bottom (which is not readily accessible for examination), where the fire impinges directly on the flat plate, and gradually burns it away. The presence of jacketted doors is also a feature of this machine, although it is doubtful if this additional com- plication is necessary when the hot-air apparatus is also supplied. The air is heated by the action of the hot gases of the fire, and the only THERHIOMETEH COLD AIR TO HIiCULATE TEMPERATURE t'ig. 4. — Section throuyli GoJJard & Co.'s square form of Washington-Lyon's disinfecting cliambei-. precaution that has to be taken in reference to this point is to warn the attendant not to raise too large a fire when using the hot-air blast ; for, if this point be not considered, the air may attain a scorch- ing temperature, and so damage the contents of the chamber. The size of this disinfecting chamber is usually 5 feet x 5 feet x 6 feet 6 inches internally, although machines of smaller dimensions are also made. The following experiment, made on a new machine in 1893, gives an idea of the working of this apparatus : — The fire was lighted at 10.8 a.m., the water in the jacket being cold, although the brickwork was still warm from the previous day's work. At 11.45 a.m. thfr DISINFECTION BY HEAT. 37 pressure gauge showed 10 lbs. steam pressure, and at 12.0 noon it indicated 194 lbs. pressure. The total time occupied for raising steam took one hour fifty -two minutes, and about 1 cwt. 1 qr. of coal had been consumed. The door was then opened for the admission of clothing. Three minutes were occupied in opening and four minutes in closing the door. At 12.10 p.m. the exhauster was set to work, and hot air was drawn through the chamber until 12.20 p.m., ten minutes in all. The chamber pressure gauge reached 5 lbs. at 12.20^ p.m. ; 10 lbs. at 12.214; 15 lbs. at 12.23; 19 lbs. at 12.27; and 20 lbs. at 12.31. During this period, from 12.20 to 12.31 p.m., the jacket pressure fluctuated between 19 and 20 lbs. At 12.23 p.m. the steam escaped freely from one of the doors which had presumably slightly sprung. This happened again subsequently, and had to be remedied by tightening the bolts securing the doors. At 12.31 p.m. the addition of feed-water to the boiler caused the pressure in the chamber to fall to 17^ lbs. Steam to the chamber was shut off at 12.35 p.m., and the chamber was then exhausted. From 12.35J p.m. to 12.44J p.m. hot air was again drawn through the chamber, and the door was opened at 12. 4S p.m. A certain amount of vapour escaped through the door on opening, and some water was found at the bottom of the chamber. The goods which were hung up, consisting of overalls, were fairly dry and not damaged. A maximum thermometer which had been exposed in the chamber registered 260° F. The total process of steam raising and first disinfection occupied two hours and forty minutes, and the total fuel used amounted to about 1 cwt. 2 qrs. The time for disinfection only after steam has been raised was forty-eight minutes. Dr. Whitelegge has been good enougii to give the following figures relating to some trials made with this apparatus at Leicester in 1889. The process was similar to the foregoing, but the total time occupied ■was only twenty-seven minutes, which, apparently, "was too little to secure penetration. The following are his results : — When removed after disinfection, a horsehair pillow, weighing originally 2 lbs. 84 ozs., was increased IJ ozs. in weight; it was damp inside but dry on cooling. The thermometer in centre indicated 241° F. A flock pillow was increased only 4 oz., the initial weight being 3 lbs. 84 ozs. This was also damp inside, but dry on cooling. The thermometer at centre showed 234° F. Three blankets, each folded into 16, piled one above the other on the floor, were wet at centre and bottom even on cooling, and the thermometer at centre indicated 166° F. Dr. Whitelegge also took the temperature of the chamber at different parts when the hot air only was admitted. Temperature in hot-air inlet, touching the pipe, was . . . 289° F. ,, on pillow 1 ft. from inlet, „ . . . 252° F. ,, on floor near inlet, ,, . . . 247° F. The temperature in chamber due to radiation and convection only, with and without air current, was as follows : — The middle of floor after 15 mins. = 239° F. , or after 5 mins. with ejector only 237° F. roof „ =245° F., „ ,, „ 250° F. The roof near door ,, =239° F., „ „ „ 246° F. The floor „ „ =241° F., „ „ „ 241° F. The other form of disinfector generally used in this country is that originally known as Washington-Lyon's, and is made by Manlove, 38 DISINFECTION AND DISINFECTANTS. Alliott & Co., Ltd., Nottingham. The leading points of difference between this and that made by Goddard & Massey are (1) that the boiler, except in the locomotive type, is usually kept distinct and separate from the disinfector, and (2) that the section is usually oval or round. As made during the past two years, the vacuum apparatus invented by Messrs. Alliott & Paton has generally been added, which is in itself a distinctive feature, although only of recent introduction. In Fig. 5 we show one of this firm's disinfectors of the old type, and in Fig. 6 the same fitted with Alliott & Paton's patent vacuum apparatus. Fig. 7 shows a portable steam disinfector for purifying wearing apparel and bedding in rural -sanitary districts. This machine has a circular chamber 5 feet long and 2^ feet diameter. The larger .^Mssj 12.9 „ ,, 12.12 „ DISINFECTION BY HEAT. 4:1 10" broken by hot air. 16" 16" circulation by hot air begun. 10" doors opened. Total tinie = 42 minutes. Total increase In weight = 1 oz., or 0'05 per cent. No. 2. — Two blankets fresh from the laundry wringing machine were next put in the disinfector. One blanket contained a large amount of soap, and it was noticeable that this one took far longer to dry than the one which was com- paratively free from soap. Before disinfection, the total weight was 15^ lbs. After 50 minutes one blanket was nearly dry, and weighed 3 lbs. .3 ozs. The soapy blanket weighed 4 lbs. 2 oza. , and was perceptibly moist. The two, therefore, weighed 7 lbs. 5 ozs., or a reduction in weight of 54 per cent. These blankets were then put back into the machine and completely dried, their total weight in that condition being about 6f lbs. No. 3. — Subsequently, a charge of bedding was treated, consisting of blankets, pillows, sheets, &c. The total weight before treatment was 29f lbs. ,, after ,, 28 ,, Total time = 35 minutes. Diminution in weight = 1 lb. 6 ozs. , or 4J per cent. In none of the foregoing experiments were the articles in any way damaged. Dr. Whitelegge also made some experiments on this form of machine in 1889, when it was not fitted with the vacuum apparatus. Permis- sion has kindly been given to refer to them here, but space does not allow of their being dealt with as fully as they deserve : — Steam was admitted to the jacket at 10 lbs., but the steam entered the chamber at a pressure of 5 lbs. only. A thermometer was placed inside one of the bulky articles to be treated, and so connected as to ring an electric bell outside when a temperature of about 220° F. was reached. The door was closed at 12.35. Steam was turned on at 12.37. 5 lbs. pressure in chamber at 12.38. Bell rang 12.53J (the bell ceased in 20 seconds upon intermitting the pressure immediately after this). Steam was shut off at 12.56. Door slightly opened to facilitate drying at 1.0. Door opened wide, dry air inside, 1.5. (a) Horse-hair pillow (2 lbs. 7i ozs.) weighed 2 lbs. 9i ozs., and was damp in centre, but dry on cooling. The electric thermometer at centre rang in 15 minutes, and corrected reading gave 223° F. (6) A flock pillow (3 lbs. 6f ozs.) weighed 3 lbs. 9 ozs. (?), and was damp In centre, but dry on cooling. The corrected temperature was 219° F. 42 DISINFECTION AND DISINFECTANTS. 2U 15 , , 20f 144 , (c) Blue Saxony flannel ^ '^ J5 afterwards measured 20"^ x j^J and was slightly yellow, but not felted. 21 1 15^ 20 J 154. (d) White, unshrinkable flannel -^ x -~l measured afterwards ^ x -j^ This also was slightly yellow, but was not felted. (e) Six samples of coloured silk, pleated, were unchanged, except that the dark green became wet and black. These had been placed near the door. (/) Thick book (OhurchiU's Directory) on floor was cool inside. Thermometer placed uncovered in other parts of machine showed temperatures varying from 228° F. to 234° F. A further experiment was then made on following lines : — Door was shut at 1.21 p.m. Steam admitted 1.22. Full steam pressure attained in chamber (5 lbs.) 1.23. Pressure was intermitted at 1.31. Bell rang at 1.35. (a) Two blankets, each folded into sixteen layers, laid one above the other on the wooden floor, were damp on removal, and dry on cooling. The electric thermometer at centre — i.e., with sixteen layers of cover — showed a corrected temperature of 228° F. The bell rang in 12 minutes. Another experiment was made with low-pressure steam, with ^ lb. pressure in both chamber and jacket. Door was closed at 2.17. Steam at -^ lb. pressure in chamber at 2. 20. Bell rang at 2.37. (a) Two blankets arranged as before were wet, but became immediately dry on shaking. The bell rang in 17 minutes, and the thermometer showed a tempera- ture of 214° F. (fc) Horse-hair pillow came out steaming, and thermometer indicated 216° F. at centre. (c) A flock pillow came out steaming, and the thermometer at centre indicated 213° F. It is noteworthy in Dr. Whitelegge's experiments, that when steam at 5 lbs. pressure was used the thermometer at centre of blankets registered 228° P. in twelve minutes, and that when steam at J lb. pressure was used the thermometer, under apparently identical conditions, indicated only 214° F. after seventeen minutes, and also in the latter case pillows were taken out steaming. Although the types of disinfecting apparatus described are not absolutely the only ones used in this country, probably more than three-fourths of those erected in the past ten years have been of these types. TYPES OF DISINFECTOES USED ON THE CONTINENT. 1. Austria — Thursfield's Apparatus. — On the Continent, several foreign designs have been extensively used, and some of these are DISINFECTION BY HEAT. 43 occasionally to be met with in this country. Fig. 9 represents a portable form of apparatus used to some extent in Austria, and Fig. 9. — Thursfield's portable disinfector (large). designed by Mr. Thursfield, of Vienna. It is, in the modern patterns, usually circular in section and jaoketted ; the jacket is partially filled with water, and acts as a boiler with the fire underneath. The boiler is open to the atmosphere, and, therefore, when steam is ad- mitted to the chamber it is only at 212° F. A continuous current of steam is kept passing through the chamber, and as the latter is jacketted by the boiler casing, con- densation is largely minimised, and the inventor states that clothing removed after treatment is only slightly damp. After each disin- fection the boiler is partially refilled with cold water, and, consequently, ebullition ceases for a time. It is stated that the boiler contains 20 gallons of water, and can generate steam in twenty-five minutes from water at 50° F. ; the total time required for one disinfection is said to be sixty-eight minutes. Fig. 10. — Thursfield 's portable disinfector (small). 44 DISINFECTION AND DISINFECTANTS. Maximum thermometers placed inside diiferent articles registered 218° F. The consumption of fuel during the above trial was said to have been only 7 lbs. wood and 19 lbs. of coal. A smaller form of the Thursfield disinfector is shown in Fig. 10. 2. France — The Equifax Stove. — A common type of apparatus in France is that made by Geneste, Herscher & Co., of Paris. This machine is externally not unlike those of Washington-Lyon, although its construction is materially different, inasmuch as there exists no steam jacket, and only comparatively low-pressure steam is employed. It is made in several sizes and types, which may be briefly described as follows : — (1) It is a fixed machine working with steam at from 7 lbs. to 10 lbs. per square inch ; consequently the maximum temperature to which the infected articles are exposed is from 230" F. to 240° F. The large size is commonly 6 ft. diameter and 13 ft. 6 in. long, inside of which are two sets of steam-pipe coils. Each set consists of eleven pipes running the whole length of the machine, one being placed at the top, the other at the bottom of the chamber. These coils are so arranged for drying purposes, and to prevent condensa- tion. Arrangements are made to enable the air to escape through a pipe at the bottom of the disinfector pending the admission of steam, with which the disinfecting process is commenced. When the pressure has reached 7 lbs. to 10 lbs., the steam is exhausted and a fresh quan- tity admitted. In this way the inventors claim that sufficient pene- tration is secured without the aid of steam at a higher pressure, and also that it is only necessary that steam at 10 lbs. be actually in contact with the goods for not less than fifteen to seventeen minutes, in addition to the time taken in filling and exhausting the chamber, which should be done not less than three times during the operation. Before the goods are taken out it is recommended that they be left in the closed machine for some time to dry, although the precise time taken by this process is not clear. (2) Messrs. Geneste, Herscher & Oo. also make a type to work at from 2 lbs. to 5 lbs. pressure with current steam. In this machine the temperature to which the goods are exposed does not exceed 217° F. to 222° F. The inventors make a point of bringing the steam into the chamber at the top and extracting it at the bottom, and say that the air in the chamber is thereby effectively driven from the chamber. The steam pressure in the case of this machine is too low to make the relaxation and renewal of pressure of any benefit to penetration. The steam is only nominally " current " because the outlet is governed by a modified form of reducing valve. A feature of the apparatus is that the two doors are so interlocked DISINFECTION BY HEAT. 45 O DISINFECTION AND DISINFECTANTS. that it is impossible to have the two doors open at the same time, but otherwise the arrangements of this type are similar to those in the other. In Fig. 11 we give an illustration of an Equifex horizontal stove working with confined steam. The disinfecting chamber, A, is a wrought^iron cylinder without jacket or other means of superheating the steam, but lagged with wood and coated with a non- conducting composition. The stove usually passes through a partition, B, to separate the infected objects from the disinfected. The doors, C, D, are fitted with an arrangement makiug it impossible for both to open at the same time, and are secured by nuts, E, looking into solid steel recesses, F, on the door.' A row of steam tubes runs longitudinally inside the stove for warming the stove before and during disinfections, and for heating the air which is used in the subsequent drying of thick objects. The steam is led to the stove by a pipe, G, from the boiler, and, after traversing a separator, H, passes through the reducing valves, I, K, and safety valves, L, M, to the stove and tubes respectively. When the desired pressure is reached in the tubes, as shown by the gauge, N, steam begins to escape through the safety valve, M, and the attendant then regulates the pres- sure by the reducing valve, K. The stove, having thus been warmed, is charged with the objects, 0, to be disinfected, which are loaded in the ordinary way on to a wheeled carriage, P, running on rails within the stove, and on hinged rails, Q, outside. The door is then closed, and locked with the safety nuts, E, and the valve, I, is opened, allowing steam to pass through the safety valve, L, into the body of the stove. The steam enters the stove through an internal sparge-pipe fitted longitudinally inside it towards the top, and furnished throughout its length with a screen to assist in the thorough projection of the steam to all parts of the stove. The steam is at first allowed to escape through the air discharge pipe, R, and carries with it the air from the stove. The discharge pipe, R, is fitted with a thermometer, S. When the air is ejected, the mercury will rapidly rise to 195° to 205° F., at which point the valve, T, controlling the pipe, R, is closed. The steam continues to enter the stove through the valve, I, till it reaches a pressure of 10 lbs. per square inch, as marked on the gauge, U, when it escapes through the safety valve, L, until the attendant has regulated the pressure by the reducing valve, I. A film of water is formed throughout the pores of the object under a pressure just sufficient to keep it from evaporating. Advantage is taken of this fact to get rid of the air secreted originally in the pores of the object by shutting oflf steam occasionally (say every five minutes) by means of the valve, I, and opening the sluice valve, V. The sudden reduction of pressure so efi'ected causes a sudden re-evaporation of the condensed steam in the objects ; so what was water in the pores expands into steam of some sixteen himdred times its volume, sweeping out before it the air from the pores. To assist this process the stove is fitted with a pneumatic exhaust, operated without any moving parts by the steam pressure. For this purpose a jet of steam is allowed, by means of the valve, W, to pass up an aspirator or ejector fitted in the steam discharge pipe, X, so automatically sucking out both the steam and the air ejected from the pores, and producing a partial vacuum under which the vaporisa- tion of the steam and the ejection of the air is completed. With objects of ordinary thickness disinfection is complete in fifteen to seventeen minutes. Steam is then let ofi' as before ; and on the door being opened, all objects such as blankets, clothes, &c., are taken out aud shaken, when they will be found to be perfectly dry. Mattresses and thicker objects are replaced in the stove for five minutes for the aspirator to withdraw the steam. DISINFECTION BY HEAT. 47 3. Denmark— Reek's Apparatus.— In Denmark, Mr. A. B. Reck, of Copenhagen, has designed an apparatus which contains some features of novelty ; but, like most of the foreign apparatus, it does not aim at so much as those of English design, and he is content to disinfect " in such a manner that things would be spoiled by steam as little as possible." The inventor attributes the presence of moisture in goods almost entirely to the inrush of cold in the presence of vapour, and his improvements are directed towards diminishing this evil. After the goods have been steamed (at about 1 J lbs. pressure), a spray of water is injected at the top of the chamber in such a way as not to impinge on the clothes, and, simultaneously, a large air valve is opened at the r |8 |8 |7 fi i- jt_j?__t_j, J Fig. 12. — Reek's steam disinfector (transverse section). bottom. It is claimed that the steam contained in the chamber rises to the top, is condensed by the cold water spray, and the momentary partial vacuum so produced is re-occupied by air rushing in at the bottom of the chamber. In this way the whole of the vapour is con- densed and carried away with the water, and when the chamber door is opened cold air only is present. The main difficulty of condensation on the clothes during disinfection due to radiation, and their own low 48 DISINFECTION AND DISINFECTANTS. temperature, is not dealt with in any way, either by steam jacketting or preliminary heating by hot air. In Figs. 12 and 13 we show two sectional views of Reek's apparatus. Dr. Reid has lately tested this form of disinfector, and has reported favourably upon it to the StaflFord County Council. 4. Germany — Scbimmers and Budenberg's Apparatus. — A disinfecting apparatus largely used in Germany is that made by Oscar Schimmel, .3Me(<.r Fig. 13. — Reek's steam disinfector (longitudinal section). of Chemnitz. There is nothing very striking in its design, and pro- bably the explanation of its extensive use may be found in the fact that it was one of the first to be placed on the market. The claims made are, broadly speaking, three. First the clothes are warmed by hot air to a temperature of 60° C; secondly, they are steamed by current steam at atmospheric pressure ; and lastly, they are partially dried, and aired again by warm air. No pretence is made that the articles come out perfectly dry, or that the process is a rapid one, but it is justifiably claimed that articles which are not too bulky are disinfected, and also that the first cost of the apparatus is moderate. DISINFECTION BY HEAT. 4:9 -fig. 14 shows a small vertical type with steam-generating apparatus and fire beneath. Steam rises round the chamber in which the clothes are situated, and enters at the top and leaves at the bottom, while condensed steam returns to the boiling apparatus. Great care would have to be exercised to see that water never ran short in the domed bottom, for it is very small in quantity, and would need frequent Fig. 14.— Schimmel's vertical steam disinfector. replenishing by hand through the funnel. When a charge has been disinfected, the fire has to be drawn in order that steam may be pre- vented from passing into the chamber. To obtain air circulation, a small door is removed in the crown, and, the exhaust pipe being also open, a certain air circulation is obtained owing to the heat retained in the clothing and walls of the chamber. In the larger size shown in Fig. 15, which is oval in section, more elaborate arrangements are provided for air heating, &c., and steam has to be obtained from a separate boiler. The gilled pipes at the bottom are filled with steam at boiler pressure, and thus to some extent they check condensation in the chamber when steam at atmo- spheric pressure is admitted. Air circulation is again obtained entirely by the crude method of opening a small door at the bottom of the DISINFECTION BY HEAT. 51 chamber close to the gill pipes, and allowing it to rise and escape at the top by the exhaust pipe. Machines of this type have been at work in Berlin for about ten years. In the larger apparatus it is usual to admit current steam to the chamber at about IJ lbs. pressure. It is necessary when working the apparatus, first to warm it up by hot air for not less than thirty minutes, and then, after putting in the goods, to again warm them for thirty minutes or thereabouts. Steam- ing is said to take about thirty minutes (although this must surely depend largely on the articles being treated), and the final drying occupies another fifteen minutes. The whole process, including load- ing and unloading the truck, should, therefore, mean an expenditure of time amounting to nearly two hours ; and, even when taken out, the articles are supposed to undergo a further process in an ordinary drying closet. i'ig. IB. — Budenberg's steam disinfecting apparatus. The general arrangements of Schimmel and Geneste Herscher's apparatus all bear a considerable resemblance the one to the other, and it is difficult to see how the actual work done by the various designs should be very different in result. It is, therefore, to the credit of Herr Oscar Schimmel that he should almost alone admit the weaknesses of his apparatus, and at the same time give financial reasons as a valid excuse. The apparatus of W. Budenberg, of Dortmund, works at about 3 lbs. pressure, and is very similar to that 52 DISINFECTION AND DISINFECTANTS. of Geneste Herscher's (Fig. 16). It has been carefully studied by Dr. Habn.* United States. — In the United States the apparatus of Geo. V. M'Lautlin & Co., of Boston, is used to some extent, as is also that of Washington-Lyons. M'Lautlin's machine bears a very close resem- blance to Geneste Herscher's apparatus, the only appreciable difference being that it is built in an apparently more substantial manner to enable it to work with steam at a pressure exceeding 10 lbs. Generally speaking, disinfecting apparatus on the Continent is built with rather a different object in view to that which obtains in this country. It is not regarded as essential for the clothes to come out absolutely dry ; and if they have to be dried by some other means after treatment, that is not considered prejudicial to the machine. Time, also, is not valued to the same extent as in this country, whereas first cost is a matter of the greatest importance. As a consequence, a cheaper machine is produced, which disinfects at the expense of wetting the goods after a more prolonged exposure. These conditions do not obtain generally in this country, for frequently, owing largely to recent regulations, the whole of the clothing and bedding of a family have to be disinfected and returned ready for use within one or two hours, whilst the family is housed at the public expense pending the chemical disinfection of their own room. The public sentiment is also in favour'of purchasing things of the most durable nature, in spite of the fact that their first cost may be greater. Lastly, the use of low-pressure steam is not largely favoured, because very bulky articles, such as bales, cannot be disinfected in machines using it ; whereas, high-pressure machines can not only deal with the bulkiest articles, but can always, if desirable, be used with low-pressure steam with equal efficiency. It is probably for these reasons that low-pressure disinfectors have been tried, and very largely abandoned at home. PUBLIC INSTALLATIONS. Plan of a Disinfector House. — The main point which has not yet been dealt with in this chapter is the arrangement of building and appurtenances requisite for a public installation. Owing to the courtesy of Mr. Rowland Plumbe, F.RI.B.A., of London, the drawings of the disinfector house and incinerator at present being erected for the Vestry of St. Mary's, Newington, are shown in the plate opposite. The particular arrangement is not one which must be followed in every instance, for each case has to be treated on its * Deutsch. Medir. Wochensch., 1890, No. 12. o NEWINGTON \'ESTIRY. NEW DIS ROOF PLAN. OCC U RATION ROAD ' DEPOT COTTAGE DUST SIFTING "O YA R D DISINFECTOR and INCINERATOR j^ SECTION A. A. SEC ELEVATION TO DEPOT. VERAN DAH r^ '■0 ^^^^ m^^^. ^ I I I I Mil ^ ELEVATION NERATOR. grjii iDnnai^^Qi m DO QD DD OB DD J^ _f_?.6:il A. A. /3i I3i S ECTI ON B. B, ELEVATION TO ROAD. '^ 1 ROOF PLAN OCCUPATION YA R D cov ERED R D l-~^6 INFECTED GOODS ^=s DlSl^ o' -^-M- K-^.O -^/8<^,-^.o -Y/e>K-- l-?.o~-i FECfTlOR 4- DISINFECTED GOODS I3'z 5)^ °R. Y'- ■g o n 18-^--^ o -^ ZO.O j|]Q|. 'J-/'. 9" -J^ ■i^jf /^.f 0| 1 — I- DEPOT YARD GROUND FLOOR PLAN VEE SECTION A. A. S EC ELEVATION TO DEPOT. VERAN DAH ■ ■_ L Y" ^ -> A □□a3[ Dana ^~\.- 5IZS?; -LU JD3 ~l — r- 1— I — ^^^^ Sr- ELEVATION END ELEVATION S ECT SCALE OF FEET. WATER LOW &S0N5 LIMITED, LONDON WALL, LONDON . -f-?-«:^ t ON A. A. SECTION B. B. EPOT ~~v- ELEVATION TO ROAD. Pa vement: ND ELEVATIOIN SECTION CO. 4-0 50 o DISINFECTION BY HEAT. 53 merits, and this building has had to be adapted to its environments. It is, however, a fairly representative installation, arranged with considerable care, and is complete, with the exception that the plan does not show the sheds for the infected and disinfected vans or hand carts, which have been subsequently erected. The main feature of a disinfector house is that there shall be two rooms ; one permanently kept for infected goods, and the other for disinfected goods. The machine is built in the wall dividing the two rooms, and is fitted with two doors, one door opening into each room. These doors should never be open at the same time, and there should be no direct inter-communication whatever. Two men should be provided to work the apparatus, one of whom should have his duties confined to the infected side, and the other to the disinfected side of the apparatus. Generally, one man only is told off to look after the ii rf^Fp Fig. 17. — Dr. Sergeant's incinerator. infected side, where the boiler and things that require atteiition are placed, and he signals or shouts to some man engaged on other work when soods have to be moved from the machine into the disinfected room. The incinerator is no essential part of the disinfection, but is, nevertheless, sometimes put on the same site for the purpose of destroying by fire bedding or clothing that is not worth disinfecting. For instance, it sometimes happens that the mattress of cholera patients are purposely of the commonest description, and only fit to burn. They can only be burned in very carefully constructed furnaces, fitted with a secondary fire to destroy the objectionable products of combustion; otherwise, the process might become a nuisance and danger to the neighbours. They are also useful for getting rid of condemned meat, offal, excreta, &c. A figure of Dr. Sergeant's incinerator, which is the one adopted at Newington, is shown in Fig. 17. At Newington, the same chimney is used for both the disinfector 54 DISINFECTION AND DISINFECTANTS. DISINFECTION BY HEAT. 55 56 DISINFECTION AND DISINFECTANTS. boiler and incinerator, but otherwise the two departments are kept distinct. The minor points to be attended to in the building for a disinfector require also some care. The floor should be of some smooth, hard material, such as cement, laid with a fall towards a drain ; and arrangements should be provided for swilling out the two rooms very thoroughly by fixing a small hose to taps in either room. All internal angles should be rounded, so as to permit of ready cleansing ; and slate and iron should be used where possible in preference to wood for the racks and fittings. Good washing accommodation and w.c. should also be provided for the attendant, and special overalls should be given him for wear whenever at work in the building. These overalls should be disinfected before allowing them to go to the laundry. Considerable attention should be paid to the ventilation of both rooms, as in summer the radiated heat from the boiler and machine is apt to be oppressive. The lighting should also be ample and well difiused, for this encourages cleanliness. United States. — For the Marine Hospital Service of the U.S. Government at the modern stations plant has been provided for disinfecting by heat, by fumes, and by chemicals. The arrangements have been described by W. H. Francis of Philadelphia,* and are shown in Figs. 18 and 19. The disinfectors are two rectangular steam-jacketted chambers 16 feet long, with steam-tight doors opening at each end. The chambers are constructed of an inner and outer steel shell, 2 J inches apart, cast-iron end frames, intermediate truss bands, and of screw stay-bolt construction. The doors have concave steel plates riveted to cast angle frames fitted with heavy rubber gaskets, they are handled by convenient cranes, and drawn tight by drop-gorged steel eye-bolts, swinging in and out of slots in the door frames. The chambers, therefore, act as drying ovens, the articles being heated before the admission of the steam, and thoroughly dried after the steam has been exhausted. A vacuum of 15-20 inches can be produced in the chamber before the admission of the steam, and any pressures up to 15 lbs. (250° F.) can be obtained. For fumigating at this station, 3 lbs. of sulphur per 1,000 cubic feet of air space are employed, and for disinfecting with liquids, mercuric chloride (1 : 1,000), carbolic acid, and chloride of lime, are at present used. * Proc. Am. Soc. Mech. Engineers, vol. xv. CHEMICAL DISINFECTANTS. 57 CHAPTER IV. CHEMICAL DISINFECTANTS. THE NON-METALLIC ELEMENTS AND THEIE DERrVATIVES. The halogens — Chlorine, chlorides, hypochlorites, chlorates — ^Bromine, bromides — Iodine, iodine trichloride, iodic and periodic acids and periodates — Fumigation — Fluorine, fluorides, silicofluorides — Chloroform, bromoform, iodoform — • Organic haloid compounds. THE HALOGENS AND THEIR COMPOUNDS. Chlorine. — About the year 1800, Guyton de Morveau in Prance, and Cruikshank in England, proposed the use of chlorine as a disinfectant. Cruikshank suggested the following method of procedure : — " 2 pts. common salt, and 1 pt. powdered manganese, with 1 pt. water and ^ pt. sulphuric acid gradually added, is sufficient for five or six beds." A similar method of generating chlorine is to gently warm one part of manganese dioxide in a granular form with four parts of concentrated hydrochloric acid (5 grms. MnOg and 20 grms. HCl give 1 litre of 01 ; ^ oz. of MnOj is abundance for a large room).* Letheby recommended one teaspoonful of powdered manganese and half a cupful of strong crude hydrochloric acid, mixed by degrees by stirring in a saucer set on a hot brick. It should be remembered that the crude acid contains arsenic, which would be evolved as the intensely poisonous arsenious chloride ; hence, at a little additional expense, pure acid only should be employed. Each of these methods requires heat, which presents great difficulties in application. Usually, therefore, the chlorine is evolved from chloride of lime by the action of moderately diluted sulphuric or hydrochloric acid. It has been stated t that 1 part bleaching powder with 2 parts of sulphuric acid of specific gravity 1-53, and enough water to cover the powder, evolved three times as much chlorine as when hydro- chloric is used. This may be due to the heat generated by the sulphuric acid, as the amounts yielded are theoretically the same, as the following equations show : — CaClaO + H2SO4 = CaS04 + H2O + CI2. CaCl20 + 2HC1 = CaClj + H2O + CI2. If the insoluble and, therefore, solid sulphate of lime keeps back less chlorine than does the deliquescent calcium chloride, the difference in the yield might be explained. * Keichardt, Desin/ectionsmittel, p. 65. + Lancet, 1888, p. 110. 58 DISINFECTION AND DISINFECTANTS. Dr. Mehlhausen * of Berlin used 600 grammes of bichromate of potash and 3 kilos, of pure hydrochloric acid, of specific gravity 1-16, for generating chlorine. These -weights yield on warming 130 -6 litres (405 grms.) of chlorine. He traced a somewhat greater activity to the gas than when prepared by the ordinary processes ; this may, perhaps, be due to some chromyl chloride (CrOjOlj) evolved in addition. The cost of this method prevents it from being generally employed. Chlorine has three possible modes of action : — 1. It may replace hydrogen in the organic substances, forming innocuous compounds and poisoning the bacteria. Such action would be slow, would scarcely occur at all except in sunlight, but yet would be the only possible action on dry matter. It may account for the antiseptic action of chlorine, as distinguished from its disinfecting power ; the latter has been questioned, but the experiments of Baxter and Sternberg on dried vaccine lymph seem to be conclusive. 2. The offensive gases of putrefaction are decomposed by chlorine ; sulphuretted hydrogen, which is always present, being resolved into sulphur and hydrochloric acid — HjS + CI2 .-= 2HC1 + S. Phosphoretted hydrogen from animal matter would be also decom- posed. Ammonia (and compound ammonias) would give first of all ammonium chloride and nitrogen — 8NH3 + 3CI2 = 6NH4CI + N2, hence the copious white fumes frequently noticed when a chlorine mixture is thrown into a dung pit. More chlorine decomposes the ammonium chloride first formed ; when this takes place there is always a formation of intensely acrid vapours which attack the eyes, owing, no doubt, to the production of chloride of nitrogen. Hydro- carbons would in most cases be little affected by chlorine, but they, as a rule, are not so offensive as the other gases mentioned. 3. The common and most important action of chlorine is as an oxidising agent. In the presence of water, more especially in light, it combines with hydrogen to form hydrochloric acid, and liberates oxygen — H2O + CI2 = 2HC1 + O. The oxygen so formed is far more active than atmospheric oxygen, and is in a condition to burn up the putrescent matters and kill the organisms which accompany the putrefaction. But there are several conditions indispensable to thorough disinfection, and amongst these (a) the presence of moisture is absolutely essential when chlorine fumi- gation is resorted to. * Berichi der Cholera Commission, 1879, vol. vi., p. ,335. CHEMICAL DISINFECTANTS. 59 (6) Quantity. — Baxter says that the disinfecting action of chlorine and of potassium permanganate depend much more upon the nature of the liquid than upon the specific organism present. Kuhn, Bucholtz, and Haberkorn have confirmed this view. For example, in a liquid like virine, which requires large quantities of chlorine, before the liquid be deodorised, the action on germs does not begin before the chlorine is in excess, and it must be maintained in excess until the last germ is destroyed, otherwise the fermentation will recom- mence. But if the action has been completed, germs that may afterwards enter from the atmosphere find it an unsuitable medium for growth. Prom this it follows that the smell of chlorine must be perceptible and persistent for some time, or no good result will have been obtained. Excess of chlorine may be chemically tested for by a paper dipped in a solution of iodide of potassium and starch paste, which is turned blue by free chlorine, or the bleaching of litmus paper may be used as an indication. Baxter in his experiments mixed chlorine with vaccine lymph, and found that its activity was not destroyed till the liquid had become acid from the presence of free hydrochloric acid. Most putrefactive organisms thrive best in alkaline solution ; hence the antiseptic power of all free acids in varying degrees. To kill pure vaccine, Baxter found the minimum proportion of chlorine to be 0-2 per cent, {i.e., soda chlorinata solution, B.P. 1 in 10 : chloride of lime, 1 in 100, both acidified). Hofmann * gives 0-15 per cent, as sufiicient for septic virus. (c) Time. — The vitality of the organisms considerably influence the length of time required for sterilisation. Sternberg t found that 1 per cent, of chlorine in air in six hours made dry vaccine inert. This is a very large quantity, for a room of 50 cubic metres would require at this rate 5 kilos, of bleaching powder, even if all the chlorine were evolved, which is generally impossible. Baxter states % that air saturated with chlorine by standing over the aqueous solution took thirty minutes to sterilise needles charged with dry vaccine. These are impossible conditions in practice. Living organisms themselves contain 90 to 95 per cent, of water, hence the disinfectant entering them would be greatly diluted. Moreover, their envelopes are often tough and resisting, especially those of germs. Therefore, more time must be given. Fischer and Proskauer,§ from laboratory experiments on spores of * Vierteljahrsschrift fiir gerichtliche Medicin, April, 1878. •\- Bulletin of the U.S. Board of Health, Washington, 1881. X Report of Med. Off. of Privy Council on Disinfectants, 1875. § Mitt, aus d. Kaiserl. Oesundheitsamte, Berlin, 1884. ,60 DISINFECTION AND DISINFECTANTS. / / anthrax and various bacteria, conclude that for air fumigation at , least 0'54 per cent, of chlorine must be present, and consider it more '! eflScacious than sulphurous acid. The experiments of Jalan de la i; Oroix,* on the putrefying bacteria of beef tea, give a surprisingly ) favourable account of the power of chlorine among the agents which V are fatal to low organisms, and place it next to corrosive sublimate as V an " anti virulent." The substances tried, arranged nearly in their order of efBciency as determined by him, were as follows : — Mercuric chloride, chlorine, chloride of lime, sulphurous acid, bromine, sulphuric acid, iodine, aluminium acetate, mustard oil, benzoic acid, sodium salicylate, potassium permanganate, phenol, chloroform, borax, alcohol, oil of eucalyptus, potassium chlorate. The methods used were first that of Bucholtz, then those of Salkowski, Wernicke, and Wernitz, and other specially devised " bacterioscopic " processes.! He concluded that " besides chlori ne, bromine, and iodine, we have only sublimate and osmic acid that will kill the bacteria of splenic fever within twenty- four hours." Given the above time, he states as to quantity that " in beef tea all growth is stopped by 1 in 30,208^i.e., 1 gramme of chlorine in 30 litres (chloride of lime, 1 in 11,135 has the same effect); 1 in 22,7^8 kills bacteria in full growth, and prevents their sponta,neous development in cooked beef tea exposed freely to air ; that of 1 in 15,606 in raw beef tea.. Chloride of lime is required in stronger doses, ■of 1 in 3,700 in cooked, and, contrary to what one would expect, 1 in 286 in raw beef tea." To destroy the germs it requires yet larger amounts, varying between 1 in 431 and 1 in 4,911 for chlorine, and 1 in 100 to 1 in 600 for chloride of lime. Vallin { throws some doubt on the above researches, and asserts that the antivirulent action of chlorine is relatively restricted, and is notably inferior to what would be presumed by the above figures. Dr. Mehlhausen§ made a number of experiments, of which the following is an abstract : — I. In a room of 37 cubic metres with door and window sealed, he placed a number of insects in gauze enclosures, and two vessels of water teeming with vibrios, rotifers, and infusoria. An earthen pot containing 740 grammes (20 grammes per cubic meti-e) of bleaching * Arch, fur experiment. PathologK, 1881. + Wernitz, Grundriss der Desinfeciionslehre, pp. 166 to 178, and Virchow's Archiv., vol. Ixxviii., pp. 53 to 60. t Train des Disinfectants, 1882, p. 118. ^Bericht der Cholera Commission, 1879, vi., p. 335. CHEMICAL DISINFECTANTS. 61 powder with a little water, to which he added 1,100 grammes of hydro- chloric acid, was also introduced and the door sealed. After nine hours the room was opened and ventilated. The animals were all living ; the flies only were insensible, but recovered on the next day. The water in the vessels, originally neutral, had become acid, and gave with nitrate of silver a copious precipitate of chloride. All the bacteria were dead. The 740 grammes of chloride of lime had given 59-7 litres of chlorine — i.e., 1'613 litre per cubic metre, or 0-161S per cent, in the air (about the amount mentioned by Hofmann, as above given), whilst some had been undoubtedly wasted by non-evolution and by leakage. II. With the same conditions as before, but with double the amount of chlorine. The vessel contained fermenting urine. In eight hours there was much residual chlorine. Most of the higher organisms were killed ; the urine had become acid, but the bacteria and spirilla were still moving. III. Equal parts of common salt and manganese dioxide, with 2 parts of sulphuric acid and 1 part of water, were warmed together, whilst putrid urine and dysenteric stools in wide flat dishes were exposed for twenty hours to the gas. On opening, only a feeble odour of chlorine was noticed, as it was masked by the effluvia from the stools and urine. Some of the organisms were only benumbed, and recovered their activity in fresh air. The liquids were very acid, and had not entirely lost their fetid odour. IV. In another room of 48 cubic metres a glass balloon was placed containing 600 grammes of bichromate of potash and 3 kilos, of hydro- chloric acid of specific gravity 1-16; by warming, 405 grammes of chlorine were evolved, equal to 2-7 litres per cubic metre, or 0-27 per cent. Under these conditions all the organisms were killed, but the time required was not stated. The process is, however, long, expen- sive, and somewhat difficult, costing about 4 centimes per cubic metre, or about Is. 6d. for disinfecting a room 11 feet square. Vallin points out that fumigations with chlorine are of little advan- tage, and are decidedly inferior to those with sulphurous acid. The disengagement of chlorine is incomplete, unless stirred and heated constantly, which is almost impossible in ordinary practice. The facility of " sulphuring " is, on the other hand, of the greatest value, and the expense is about four or five times less.* Jeannel t noticed that chlorine seemed to have only a temporary action on certain vibrios, as he was able by means of ammonia to restore them to activity after they had been subjected to the influence of chlorine for a long period. * See Sulphurous acid, later. t Union M4dicale, Sept. 28, 1871. 62 DISINFECTION AND DISINFECTANTS. The experiments of Sternberg* concerning the action of chlorine on infusoria and micro-organisms show that the resistance of the latter is considerable. In an experimental room of 10 litres capacity, he placed 28 grammes of chloride of lime. It was an hour and a half before the movements of the bacteria contained in a drop of putrid meat infusion ceased, although the watch glass holding the liquid was directly exposed to the gas. (If he did not acidify, the only chlorine evolved would be that liberated by the small quantity of carbonic acid in the air present — namely, about 0'071 per cent. — which is too small a proportion, if we take Hofmann's minimum of 0'16 per cent., or Baxter's 0'2 per cent, be admitted.! But the total amount would still be immense if it could be absorbed by the drop of fluid, as it would reach 7 grammes of chlorine in the 10 litres of air.) Sternberg did not consider the movements definitely destroyed until after an hour's exposure to fresh air, they had not reappeared. Dr. Cash | subsequently studied the action of chlorine, and en- deavoured to determine the comparative value of the halogens and of sulphurous acid in destroying the virus of anthrax and tubercle ; he concluded that the halogens do not present any great difi'erences when employed in solutions, the strengths of which are proportional to their atomic weights, though cjilaiine was the least active and iodine the most. This would oblige us to use 127 parts of iodine for 80 of bromine and 354 of chlorine. He found that when employed in dilute solutions they did not disinfect. (That is, below Baxter's limit of 0-2 per cent.) He prefers sulphurous acid if the disinfecting agent be employed as a gas, but considers it better to employ a solution of the gas if possible.§ (d) Contact. — Intimate contact between the gas and the centre of infection must be assured. If large masses of putrescible matter like fseces are present, chlorine gas fails in its action, and must be supple- mented by the addition of metallic salts, &c. For if all easily de- composable organic matter be not destroyed, a recommencement of putrefaction is not prevented. || Klein ^ used chlorine fumigations in stables for disinfection from swine plague with success. When in great mass — e.g., dung and straw in typhus — care must be taken not to give a false security by illusory means. Probably in many cases it is better to rely on purification being accomplished naturally * Bulletin of National Board of Health, WasMngton, July 23, 1881. t See later, under Chloride of lime. tPharm. Journ., 1887, p. 485; L. G. B. Sixteenth Annual Report, § See later, Sulphurous Acid. || Reiohardt, Desinfectionsmittel, p. 57. IT L, G. B. Thirteenth Annual Report. CHEMICAL DISINFECTANTS. 63 by air and moisture than run the risk of natural decomposition being retarded by the employment of inefficient quantities of antiseptics. It must be remembered that manure that has been treated with chlorine or chloride of lime loses all its agricultural value on account of the destruction of its ammonium salts. On the other hand, if chloride of lime is sprinkled over faecal matter before removal, it destroys any offensive gases that may be evolved. It cannot be too strongly emphasised that air cannot be disinfected and still remain fit to breathe. Wernitz * condemns all fumigations as useless, classing all methods as "illusory specifics,'' since "we require a body which shall come in intimate contact with atmospheric dust, and act for a long time on it.'' Vallin says " disinfection of air is useless and gives a deceitful security. To make a strong odour of phenol, or put a basin of chlorine in a corner, is, with regard to de- struction of virus, an operation quite futile, as the virulent particles in air are probably protected by an envelope of dried albuminous matter." Chloride of Lime and Hypochlorites. — By treating the alkalies and alkaline earths in solution with chlorine in the cold, mixtures of chloride and hypochlorite are formed which have been long known as useful disinfectants. Liquor sodse chlorinatse, B.P., chlorinated soda, or " Eau de Labarraque " has a strength of 2 J per cent, of available chlorine. It is used in surgery diluted with 10 parts of water (equal to Baxter's effective strength of 0-2 per cent. CI) as an antiseptic lotion, and is refreshing and non-irritant. By its decomposition it produces a small quantity of common salt. It has also been employed as a mouth wash. "Eau de Javelle," introduced by Percy in 1793, is similarly made, but with potash instead of soda, and is said to keep longer than the soda compound. The orders of the French Prefecture recommended 1 part of Eau de Javelle of 18° Baume to 100 parts of water for flushing closets and washing walls, &c. It has the advantage over " chloride of lime " that it does not leave behind a deliquescent body like calcium chloride. It acts similarly to chlorine. " Chloride of lime" or bleaching powder, obtained by passing chlorine over moist slaked lime, has the advantage of being a dry powder, which is more easy of transport and keeps better than the soda and potash preparations. It is a mixed chloride and hypochlorite of the formula CaCLO, and breaks up into chloride and hypochlorite on solution in water. The latter is strongly alkaline, and is acted on by the carbonic acid of the air giving carbonate of lime and hypochlorous acid. 2CaCl20 = CaClj + Ca(C10)2 Ca(C10)2 + CO2 + H2O = CaCOg + 2HC10 * Desinfectionalehre, 1882. 64 DISINFECTION AND DISINFECTANTS. In contact with organic matter the hypochlorous acid splits up into hydrochloric acid and oxygen, and it is on this liberated oxygen that its value as a disinfectant depends. The calcium chloride remains behind as a deliquescent salt, and this is an objection to bleaching powder being mixed with lime for white washing, as the surface remains damp. It is important to remember that chloride of lime must be acidified, either slowly and spontaneously by the carbonic acid, or by the addition of hydrochloric or sulphuric acid or even vinegar, for any chlorine to be liberated. Weak acids only decompose the hypochlorite, leaving the chloride untouched, and evolve hypo- chlorous acid. Strong mineral acids, on the other hand, evolve chlorine. To prove the necessity of acidification, D'Arcet and Gaultier de Olaubry showed that air deprived of carbonic acid by a potash wash- bottle, and then passed over chloride of lime, was not disinfected. Good bleaching powder contains 34 per cent, of available chlorine. It is best used in the proportion of 1 part to 10 or 12 parts of water. It should be freshly prepared, and kept from light and air. When old it becomes damp and is then of inferior value. Similar preparations of aluminium and magnesium hypochlorites have been made by precipitating a solution of chloride of lime by sulphates of aluminium or magnesium. The latter has no special advantage, but the former has in addition the mordanting and clarifying and antiseptic properties of other aluminium salts (see Chloralum, p. 131), and might deserve more extended use. It is commercially used for bleaching paper pulp, under the name of Anderson's solution. The American " standard solution of chloride of lime " is thus described : — " Dissolve chloride of lime containing not less than 25 per cent, of available chlorine, 6 ounces to 1 gallon of water (4^ per cent.). Use 1 quart for each discharge in cholera, typhoid, rH2, which are usually crystalline, neutral com- pounds which are soluble in water and more or less volatile. A few, like acetanilide, are antiseptic. Hydroxylamine, NHjOH, has been tried by Bing and others in skin ■diseases. It acts as a reducing agent and is a strong germicide. Hydrazine or Diamine, ISTgH^, has been found by Loew and Buchner to be powerfully poisonous to animal, vegetable, and bacterial life. Methylamine, OHgNHj, is a gas with a strong alkaline reaction. It is more basic and more soluble in water and in alcohol than ammonia. Its odour is like that of herring-brine, in which it is contained. The hydrochloride, (CH3)]S'H2.HC1, crystallises in deliquescent, very solu- ble plates, which give off methylamine on treatment with potash. The sulphate forms an alum, (CH3]S'H2)2H2SO^, Al2(S04)g, SiHaO ; this is a powerful disinfectant, but has not been much used. Dimethylamine, (0113)2X11, occurs in guano and, in small quantities, in pyroligneous acid. It resembles the preceding. Neither of them seem to have met with any practical application. Trimethylamine, (OH3)3N', is a very volatile, alkaline, and inflam- mable liquid, extremely soluble in water and alcohol. It also has the fishy and ammoniacal odour. It is obtained from herring-brine, and is made in large quantities, with ammonia, dimethylamine, methyl 184 DISINFECTION AND DISINFECTANTS. alcohol, and methyl cyanide, by distilling " vinasse," a residue of the beet-sugar manufacture. The source is " Betaine,'' the internal anhy- dride of trimethyl-amido-acetic acid, CH2.CO.O.N(CH3)3. In Patent No. 16,242, 1888, H. WoUheim claims its use "for de- stroying, in a very short time, the vitality of all germs and spores which can produce disease." Its compounds with acids crystallise well, and resemble the ammonia salts, but are more soluble in alcohol, and are said to be poisonous. The Ethyl- and Propyl-amines are similar, but of greater density and higher boiling point. Propylamine, (CgH.^)NH2, is metameric with trimethylamine, and resembles it. Amylamine, (OjHy)NH2, is contained in the products of destructive distillation of animal matters, such as bone oil. It is a liquid smelling like burnt feathers, is antiseptic, but seems to have no sf)ecial advantage. The Amines process for treating sewage consists in the utilisation of herring-brine with lime. This liquid is a mixture of amines, with trimethylamine predominating. Klein and others, who tested the effluent bacteriologically, reported very favourably on the process, asserting that the result was complete sterilisation, that 1 per cent. of trimethylamine was sufficient, and that the operation was easy and inexpensive. Objections were made by others on the score of (1) the offensive odour of the precipitant; (2) its deterioration on keeping ; (3) in the case of its application inland, the quantity of salt that must be discharged into rivers ; (4) the danger of the effluent being poisonous to river-fish (this is not proved of the small quantity of trimethylamine that would remain as, being volatile, most of it evaporates into the air) ; (5) the alkaline character of the clarified water ; and (6) the difficulty of procuring a sufficient supply of herring- brine. "Aminol" is the name given to the mixture of methylamines obtained by distilling herring-brine with lime according to the patent mentioned above. It is a clear colourless liquid, alkaline and odorous of the bases. It is permanent when kept tightly enclosed, but easily loses strength when opened. Two solutions are applied: — "D" (disinfecting) for general disinfecting purposes, is said to be a "perfect deodoriser, non-poisonous, non-corrosive, and does not stain;" and "R" (Remedial), for medicine and surgery, "efficient remedy in all suppurative, phlegmonous, or fermentative disease processes." Aniline, C(.H5(]SrH2), amido-benzene, is now made on a large scale by the reduction ot nitrobenzene by iron filings and acetic acid. The residue, acetate of iron, is oxidised to "red liquor," ferric acetate, and has been used in France as a disinfectant. Aniline also occurs in bone-oil (p. 190). ORGANIC SUBSTANCES. 185 It is an oily liquid, colourless when pure, but turning brown in air and light, boiling at 184° C, but easily volatile with the vapour of water. Its melting point is 08° C, and specific gravity 1'036. It is soluble in 31 parts of water, very soluble in alcohol, &c., and forms soluble crystalline salts from which the base is again liberated by potash, soda, or lime. It is poisonous, and hence a germicide. It slowly volatilises at ordinary temperatures, giving a vapour of oppressive tobacco-like odour, which also kills bacteria, but does not easily affect their sporesv Pettenkofer and Lehmann assert* that 0-1 per cent, of aniline vapour in air is dangerous to man and animals. From this fact, and the slow rate at which it diffuses, its use for fumigation is negatived. The salts are antiseptic, and, being acid, absorb ammonia and com- jiound ammonias, but not sulphuretted hydrogen. Angus Smith j places aniline in his sixth class — i.e., as moderately antiseptic. Dr. Fischer has shown that tubercular sputa mixed with ten times its volume of aniline water, is completely disinfected in twenty-four hours. This is equivalent to the action of a 5 per cent, carbolic acid. At the present price of aniline, it seems to be a disinfectant which is worth trying. Substitution Products. — An immense number of these have been obtained, aniline being much more easily acted upon than benzene. They are generally antiseptic, but have hitherto not yielded any satis- factory results for hygienic purposes, and are less soluble and volatile, and often more poisonous than aniline itself. Acetanilide, " antifebrin," or phenyl-acetamide, C'uH5.NH(CO.CH3), prepared by boiling aniline with glacial acetic acid for several days, is a white crystalline and easily soluble powder. Its melting point is 114° {Ritsert), and boiling point 295°. Potash and acids slowly reconvert it into acetic acid and aniline. In 3- to 8-grm. doses it is antipyretic and analgesic in fevers ; externally it has been used as an antiseptic for wounds, but 30 grains in twenty-four hours has been found to produce poisonous symptoms. A special therapeutic commission! pro- nounced it inferior to phenacetin and antipyrin (p. 189). Para-brom-acetanilide, "asepsin,'' or " antisepsin," C6H,Br.NH(CO.CH3), is said to be anodyne and antiseptic. This must not be confounded with "aseptin." Aniline Dyes as Antiseptics. — Several of these have long been known to have the power of penetrating into living animal and vegetable * Acad. d. Wissensch. zv, Munchen, 1887, p. 179. t Dmnfectants, Edin., 1869. + Brit. Med. Journ., 1894. 186 DISINFECTION AND DISINFECTANTS. structures, different dyes selecting different parts and species ; there- fore, they are widely employed for microscopic staining. Their action occurs in extremely dilute solutions, and is out of all proportion to their poisonous action on higher animals. The effect is to lower the vitality of, and, finally, to kill the organ- isms. Hence it became a matter of interest to see how far they could he used as actual disinfectants. Koch proved* that a number of the tar dyes were inhibitory to tubercle and other bacilli, both in local and in internal application. The Methyl Violets are mixtures of hexamethyl-rosaniline hydro- chloride — [OeH,.N(OH3),], 0,H,.N(CH3)2.C1, "with the salts of penta- and tetra-methyl rosanilines. They occur in amorphous, dark blue masses (the pure hexa-compound is in large ■deep violet -crystals), soluble in alcohol, sparingly in water, but gives it an intense violet colour. Professor Stilling, of Strasburg, has experimented on the disinfect- ing power of methyl- violet, and has found that a paste made with wheaten flour, with a 2 per 1,000 solution of methyl- violet added, does not turn sour, however long it is kept. Milk mixed with the same quantity does not turn sour, butter and bacon soaked in a ■stronger solution (1 in 500) and dried, become superficially stained, but do not afterwards become rancid. Mucor stolonifer was sown upon rolls of bread, some of which were soaked in a 1 in 500 to 1 in 1,000 solution of the dye, and some in water only. On the latter a growth appeared in twenty-four hours, whilst on the former none «ould be noticed after fourteen days. He has given the name of ■" pyoctanin," from -Truog, pus, and -/.raoi, stain, to methyl violet, and says it can be had absolutely pure from the firm of E. Merck, of Darm- ■stadt. " Certain auramines proved to be the next best, when used in solutions of 1 in 4,000 to 1 in 1,000." t Dr. C. Prioux X points out that solutions of pyoctanin and gentian violet, 1 in 100 prevent the development of micro-organisms. Weaker solutions (1 in 500, or even 1 in 2,000) arrest the cultures of typhoid .and Bacterium coli communis (the ordinary microbe of the intestines) • * Mittheil. a. d. K. Gesundh., 1881, vol. i., p. 234. t Lancet, 1890, vol. xi., p. 965. t International J. uf Microscopy and Nat. Science, vol. iii., part 18. ORGANIC SUBSTANCES. 187 1 per cent, solutions of safranine (an orange-red dye containing at least three " benzene rings ") have also been shown to hinder Eberth's bacillus from developing. Solutions of blue pyoctanin for general surgery, ointments, powders, and dressings have been introduced. Dr. Petersen found that these preparations were as effective as those made with iodoform, without the unpleasant odour, and without any bad effects or symptoms of poisoning. Dr. Wanscher strongly recommended a 1 per cent, solution for ophthalmic use and in urethral discharges, as lessening local irritation. They have also been used for nasal and other cavities of the body, to stop suppuration. Von Mosetig treated malignant tumours by injections of methyl violet, and believes that complete cure by this method is possible. Yellow Pyoctanin is an "auramine,'' obtained by acting on dimethyl- aniline with phosgene, and then by ammonia ; its formula is 0[C5H^. N(OH3)2j2. NH. It is a para-derivative of benzophenone, and is specially recommended for ophthalmic practice. "Apyonin'' is said to be also an auramine, and is intended for the same purpose as the last. PYRROL COMPOUNDS. There are other rings analogous to the benzene ring, but containing 4 or 5 atoms instead of 6. Those with 4 carbon atoms include these three chief compounds : — Furturane. Pyrrol. Thiophene. CH = CH, CH = CH, OH = CH ^NH >S CH = CH/ CH = CH^ CH = CH All three are tar products, are volatile, colourless liquids, with antiseptic characters that have not been well studied. Furfurane, C^H^O, is a mobile liquid with an odour like chloroform, and boils at 32° 0. It appears to be present in pine-wood tar, together with methyl-furfurane, or sylvane, C^Hg(CH3)0, which boils at 63° C. Furfurol, C^H3(00.H)0, is the corresponding aldehyde, and is formed by the action of acids on sugar, bran, &c. (Furfur, bran). Thiophene, C^H^S, is found in commercial benzene, and smells like it ; it boils at 84° C. It is probably an insecticide if not a germicide. It is insoluble in water, but soluble in oil of vitriol, forming a sulphonic acid, O^H3S(S03H). 188 DISINFECTION AND DISINFECTANTS. Pyrrol, C^H^(NH), is colourless, but becomes brown in air (like most of these bodies). It boils at 133° C, has a specific gravity of 1'077 {Anderson), a faint odour like chloroform, and a hot, burning taste. It is insoluble in alkaline solutions, but is slowly dissolved by acids. It is contained in coal tar, but is generally made from bone oil. Alcoholic solutions of pyrrol precipitate mercuric chloride. "lodol," tetra-iodo-pyrrol, C^I^(]SrH), is made by the action of iodine and potash on pyrrol. It is a pale yellow, inodorous and tasteless, crystalline powder, almost insoluble in water, soluble in 18 parts of alcohol, 155 of glycerine, 1| of ether, and in oils. It decomposes at 140° 0. with violet vapours of iodine. It gives a black precipitate with mercuric chloride (hence incompatible with it), and is decomposed by hydrochloric acid, iodine being liberated. It is reputed to have antiseptic properties, and is used for the same purposes as iodoform, but has not the objectionable smell, and is not so poisonous, but Riedlin says * that it has no action on cholera or any other bacteria. " Antipyrin," Oj^HjjNgO. — By substituting a nitrogen atom for one of the (CH)'" groups in pyrrol, the grouping known as pyrazol, CjHg.N.NH, is obtained. A body of ketonic character called pyra- zolone, OH :N\ I > NH, CHyCO/ is an oxy derivative of this compound. From it phenyl-methyl- l)yrazolone, C(CH3) : N \ I >N(C,H,); CHo.CO / and phenyl- dimethyl -pyrazolone or "antipyrin"; abbreviated in the British Pharmacoiiceia to "phenazone" are obtained — Pyrrol. CH = CH CH = CH' nNH Pyrazol. CH = N , OH = OH'' Pyrazolone. CH = isr . >]SfH )NH OH,- CO' Phenyl-methyl -pyrazolone. Phenyl-dimethyl-pyrazolone (antipyrin). C(CH3) = N C(OHg) ^(CH.,) >N(CeH,) OH2 — 00''^ OH — CO * Archiv.f. Hyg., vol.. vii., p. 309. >N(CeH,) ORGANIC SUBSTANCES. 189 L. Knorr's patent* heats phenyl-hydrazine, NH2.NH(CuH5), with ethyl aceto-acetate, CHj(CO . CH3) . CO . 0(02H5), when water and alcohol are separated, and phenyl-methyl-pyrazolone formed ; methyl iodide converts this into antipyrin. Antipyrin, or "phenazone," crystallises in colourless scales, neutral, inodorous and slightly bitter, fairly soluble in water, alcohol, and chloroform, less so (about 1 in 50) in ether. It dissolves in acids to colourless solutions. Melting point, 113° C. It has been found mixed with acetauilide (p. 185), which is much cheaper; but the detection is easy, as, although the melting point of the latter is also about 113°, a mixture of the two melts about 45° C. It is antipyretic and antiseptic, also an anodyne for neuralgia and gout (see Antifebrin, p. 185). Externally, it has found favour as an antiseptic lotion, and as gauze. It is incompatible with tannin, many acids, ferric salts, iodine, and a number of drugs. llfitro- and " isonitroso "-antipyrin, " salipyrin " (a salicylate ), " iodantipyrin " or " iodpyrin," " resopyrin " (a compound with i-esorcinol) have been prepared. PYRIDINE GROUP, &o. If, in the benzene ring, nitrogen be substituted for a CH group, pyridine, O^H^N, is obtained. From naphthalene and anthracene, similar nitrogen derivatives are formed : — Benzene. CH / • CH CH !l I CH CH \ ^ CH Pyridine. CH / % CH CH CH CH Naphthalene. CH CH CH I CH C S / \ ^ CH CH Quinoline. CH CH CH I CH CH CH C II c CH CH \ / CH N /• CH Anthracene. CH CH CH ' \ / \ / ^ c c CH C \ / ^ CH C . / CH CH CH C C ^ / \ / \ , CH N CH CH I CH Acridine. CH CH CH ^ \ ' \ / \> CH C C CH CH Additive compounds, of which piperidine or hexahydro-pyridine, CjHjdNH, and nicotine or hexahydro-dipyridyl, (C5H^N)2Hg, are examples, are also known. The radicles, methyl, ethyl, &c., can * Liebig's Annalen, vol. coxxxviii., p. 137. 190 DISINFECTION AND DISINFECTANTS. also replace the hydrogen atoms giving homologues of pyridine, which exist with it in coal-tar, and in larger quantity in bone-oil. They much resemble pyridine in properties, but rise in boiling point and diminish in density as the number of carbon atoms increases, and are more readily oxidised and attacked. The mono-, di-, tri-, tetra-, and penta-methyl derivatives have been obtained by the fractional distilla- tion of bone-oil, the fractions so procured being mixtures of isomerides, which it is impossible to separate by this method. They were dis- covered by Anderson in 1846, and investigated also by Greville Williams, Ladenburg, and others. Table of the PrRiDiNE Homologues. Constitutional Empirical Boiling Specific Formula. Formula. Point. Gravity. Pyridine, CiHsN 117° C. •985 Picolines, CsH4(CH3)N C„H,N 135° ■961 Lutidines, CsH3(CH3)2N CjHgN 154-5° •946 CoUidines, CsHjCCHalsN CsHnN 180° •944 Parvolines, C5H(CH8)4 CgHisN ... Caridines, C.,(CH3)5N C10H15N 211° llubidine, ?C5(C2H5)(CH3)4N C„Hj,N 2,30° ViridiDe, ?C5(C3Hy)(CH3)4N C12H19N 251° Coiune, CgH^yN, the volatile alkaloid of hemlock {Gonium macula- turn), is normal-propyl-piperidine, C5HjqN(C3Hy), [Ladenburg). Piperine, from pepper, is peperyl-piperidine, CsHjqN CjgHgOg, related to pyridine through piperidine (ibid). It will be noticed that aniline, CjH5(NH2), is metameric with the picolines, 05H^(CH3)lNr, of which all the three possible isomerides have been separated from bone-oil. All these substances are more or less narcotic poisons ; hence, would act as antiseptics, and, if in sufficient quantity, would kill bacteria. It has been mentioned that Saprol (p. 165) contains pyridine bases : from most coal-tar disinfectants they have been removed together with aniline by treatment with acids, but some of the newer preparations contain appreciable quantities of these bases. The most important is — Pyridine, C5H5N. — When pure it is a mobile, colourless liquid, which does not turn brown in air and light, and is slowly and com- pletely volatile. Its odour is said to be " empyreumatic," but is most persistent and unpleasant. It absorbs water from the air, and mixes with it in all proportions ; it is also readily soluble in alcohol. It forms soluble crystalline salts with acids. Commercial ammonia often contains pyridine, and commercial pyridine is sometimes contaminated with ammonia. ORGANIC SUBSTANCES- 191 Tobacco-smoke, contrary to popular belief, does not contain nicotine, ■which is decomposed by the heat, but pyridine and its horaologues, and the beneficial effect of tobacco in many cases of asthma, must be attributed to these latter, whether as sedative or as bactericide (it- must be remembered that very little of the smoke itself gets into the- lungs). Pyridine inhalations have been proposed for asthma. "Prom 1 to li drachms are poured on a plate and placed in a room with the patients. At 68° to 77° P. the above quantity evaporates in about an hour. It is said that after a few minutes' exposure to the pyridine atmosphere the remedy can bo detected in the urine. The treatment- ■was -well spoken of by Dr. Kelemen, among others, but does not seem to have maintained its ground. Mixed with a little oil of peppermint- it has been employed in the treatment of diphtheria with some- success, and in aqueous solution (1 in 300) three or four injections have been recently said by Rademacher to be sufficient to cure- gonorrhoea." * It was stated by the Cigar Manufacturers' Association of Hamburg that in the last visitation of cholera there were only eight cases and four deaths amongst a body of 5,000 cigar-makers. Dr. Burney, the senior Medical Officer of Greenwich Workhouse^ asserts that the tobacco-smoking inmates enjoyed comparative im- munity from epidemics, and tobacco-smoking is believed to have had a disinfectant action in cases of cholera and other infectious diseases. But Dr. Kerr points out that if a man cannot stand smoking it may- depress his heart, action and enfeeble his constitution, and so lessen the resisting power to throw off the noxious germs. Pyridine fumi- gations are also open to the same objection. It is recorded that Tessinari found that tobacco-smoke, on being passed through tubes- containing a niitrient gelatine and pathogenic germs for from ten to- thirty minutes, destroyed the bacilli of Asiatic cholera and of pneu- monia. Pyridine was introduced by O. Fergusson as a horticultural insecticide about 1890, but its odour was against it, although it was most effective. Wynter Blyth exposed the yellow bacillus of nasal catarrh, on threads, to the action of a 1 per cent, solution of a mixture of pyridine, collidine, lutidine, and acridine from bone-oil. After the threads were washed and transferred to nutrient gelatine, there was no growth. In sour milk also, pyridine inhibited growth. Tobacco- smoke passed through water killed the yellow bacillus. These experi- ments tend to confirm the idea that disinfectant preparations containing the basic constituents of coal tar are to be preferred to those only containing the phenols, also that pyridine being very soluble in water and non-irritant, might be of service in nasal affections. * Helbing, Mod. Mat. Med., p. 65. 192 DISINFECTION AND DISINFECTANTS. Nicotine, Ci(,Hg(Hg)N2, is an oily liquid which rapidly turns brown in air. It boils at about 250° C, but is readily volatile with steam. It has a well-known stupefying odour, is alkaline, dissolves easily in water, alcohol, and ether, forms crystalline salts with acids, and is extremely poisonous. Its use as an insecticide in gardening is familiar. At Greenwich iu 1893 the use of tobacco seemed to be protective in an epidemic of English Cholera. Nickels* covers the use of shale or bone-oil, or pyridine bases, with resiii and soda, as a disinfectant. Overbeck f proposed the use of pyridine or leucoline (quinoline, see below) with chalk or lime. Indole, CgH^<^pTT ^CH, crystallises in plates, moderately soluble in water, easily in alcohol and ether, melting at 52° C, feebly basic, Jhaving a peculiar fsecal odour, and giving a red colour or precipitate of nitroso-indole with sodium nitrite and dilute sulphuric acid. It readily volatilises with steam. As a product of putrefaction it has been presumed to be antiseptic, but its odour would preclude its practical use. It has derived a certain importance from the fact that it is constantly formed in the growth of the bacillus of typhoid and the spirillum of cholera. Bujwidj first proposed the "indole test," as given above, to distinguish these pathogenic organisms from others that are innocuous. But unfortunately Bacillus coli communis, which is commonly found in the intestines and in water contaminated with normal fieces. also forms indole, as might be expected from the latter being always present in small quantity in the intestines. Tyrosine, CgH^(OH).CH2(NH2).OOOH, /3-oxyphenol-amidopropionic acid, is also a constant product of the putrefaction of albuminoid sub- stances, and has been said to be strongly antiseptic. It crystallises in minute needles, which are inodorous, almost tasteless, and nearly neutral. It seems to be worthy of experiment. QUINOLINE DERIVATIVES. Quinoline, chinoline, or "leucoline," CjHjN", is a colourless, highly refracting, oily liquid of a disagreeably pungent and aromatic odour, and a bitter acrid taste. In light and air it rapidly turns brown. It melts below 4° C, boils at 237° C, and has a specific gravity of 1-081. It dissolves sparingly in water, easily in alcohol, &c., to an alkaline solution, and with acids forms soluble crystalline salts. The salicylate and tartrate have been used in medicine, both internally and ex- ternally. Quinoline occurs in coal-tar, &c., with two homologues, " Patent No. 3,053, 18S3. t Patent No. 3,199, 1883. t Zeit.f. Hyg., 1887, vol. xi., p. 52. ORGANIC SUBSTANCES. 195 lepidine, CjoHglSr, B.P. 265°, and cryptidine OnHuN, B.P. 274° C. Quinoline is incompatible with oxidants, with iodine solutions, and with metallic salts ; it is antiseptic, and is the subject of the following patent*: — "It has been proved that quinoline and toluquinoline possess great antibacterial properties, but the complete insolubility of these substances in non-acid fluids presented a serious obstacle to their use. This invention consists of using as a solvent soap in the nascent state," as in creolin, &c., "50 kilos, of castor oil, 50 of quinoline, by the clearing of the liquid, which is then diluted with 85 kilos, of water." Quinoline does not saponify, so that the solution would contain 20 per cent, of quinoline dissolved in aqueous soap, and would become turbid with water like creolin. " Diaphtherin " was introduced by [Prof. Emmerich and Kronacher, of Munich,t who, after extended trials, pronounced it to be " equal, if not superior, to previously known antiseptics." It is said to be di-oxy- quinoline phenolsulphonate, 2CgH5(OH)N,0(iH^(OH).HSO3. {Ortho- phenolrsulphonic acid, or "aseptol," p. 158.) It is a yellow powder, readily soluble in water, decomposed by alkalies and even by blood, with elimination of sparingly soluble oxyquinoline in a fine state of division ; hence, when applied to wounds, it does not lose its antiseptic power as some phenolic substances do (it does not coagulate albumen). Emmerich administered 0'25 gramme subcutaneously to guinea pigs, without prejudicial results. "A 1 per cent, solution is sufficient for antiseptic dressings." a-Oxy-quinoline or carbostyrile, CgH5(0H)]Sr, occurs in white needles, melting at 198°, and is strongly antiseptic. It is the source of:— "Loretin," iodo-oxy-quinoline sulphonic acid, CgH5l(OH:)]Sr.HS03, lately introduced as another substitute for iodoform, and reported on by Prof Schinzinger, of Nuremberg. He showed that its action on granulating and healing processes is a very favourable one, and is superior to that of iodoform, while it is free from objectionable odour, not toxic, and non-irritant, and rapidly removes any eczematous tendency. It is also a good deodorant of purulent secretions and decomposing tissues. "It is very beneficially employed to combat external and parasitic diseases, and as an antiseptic may be blown into cavities for internal affections." Quinoline when reduced forms a tetrahydride, CgHj^N, which is more strongly antiseptic than quinoline. "Thalline" is para-methoxy-quinoline tetrahydride, C9Hj|,(O0H3)N. According to the specifications {Skraup, 1885) it is made like quinoline, * No. 18,913, 1891 ; Lembach, Schleicher, and Wolff. t Munch. Med. Wochensehr., 1890. 13 194 DISINFECTION AND DISINFECTANTS. by heating methoxy-aniline (para-amido-anisol) with glycerine, sul- phuric acid, and paranitro-anisol, and then reducing to the tetrahydro- compound. It is an oily liquid, easily frozen, and then only re-melts at 180°, with a strong odour like Tonka beans, and soluble in acids to- form crystalline salts. Ferric chloride produces an intense green, colour, hence the name (6aX}.6s, a green twig). The sulphate and tartrate are found in commerce as yellowish-white- crystalline powders, soluble in about 7 and 10 parts of water, sparingly in alcohol. They are acid, fragrant, and bitter, and darken in light. In a paper by H. Schultz " On the Influence of Thalline Salts on Putrefaction and Permentation,"* he states that "0-5 per cent, of thalline sulphate in sterilised gelatine prevented the further putre- faction of meat. Yeast fermentation was considerably retarded by 1 per cent, of thalline tartrate ; with a less quantity, however, the activity was increased," probably by supplying nitrogenous food to the fungus. It must be observed that the agent would not answer for a. food-preservative, on account of its taste, odour, and physiological action. Thalline was at first extolled as a substitute for quinine, 2 to 8 grains of sulphate or tartrate being given in aqueous solution,, but the salts are poisonous to the red blood corpuscles and act on the nerve centres (Brouardel). As antiseptics they are still occasionally used for injections (4 to 8 grains to the ounce) in gonorrhoea. Quinine, CjoHg^NjOjjSHgO, appears to be a derivative of a partially hydrogenised di-quinoline, and to have the formula CgHe(0CH3)N - OgHji(OH)KCH3, although it has not yet been synthesised. t Its action against fevers- is probably as much due to its antiseptic power as to its effect on the nervous system. The natives of Peru were in the habit of purifying the water of fetid pools by throwing in logs of cinchona [Humboldt), but the tannin would also take part in this treatment. Koch observes : " The dose of quinine necessary to destroy the spirilla of relapsing fever would be 12 to 16 grammes, which would kill the host as well as the parasite." A much less dose is sufficient to restrain the spirillum. Antiseptol, iodo-sulphate of cinchonine, contains 50 per cent, of iodine, and is said by Yvon % to be a powerful antiseptic for surgical use. It must not be confounded with other antiseptics having a similar name. ■" Centr. Med. Wissensch., 1886, p. 113. t Liebig's Annalen, vol. cciv., p. 90. t Amer. Journ. of Pharm., Oct., 1890. OEGANIC SUBSTANCES. 195 CHAPTER X. OEGANIC COMPOUNDS (continued). ACIDS DERIVED FROM BENZENE. Benzoic Acid : Its Use as an Antiseptic— Benzo-boraoio Acid, &c. — Benzoic Aldehyd, or Oil of Bitter Almonds — Sulpho-benzoic Acid — Benzosol — Benzo- paracresol and Benzo-naphthol. Salicylic Acid : Its Three Isomerides — Salicylates — Oil of Wintergreen — Salol — Salophen — Phenosalyl — Antiseptic Value of Salicylic Acid — Patents — " Lactacidine " — The Use of Salicylic Acid for Preserving Food — Objections — Tablets, Gauze, &c. — Anisic Acid — Cinnamio Acid, Styracol — /3-Phenyl Propionic Acid — Phenyl Acetic Acid — Gallic Acid — Tannin — Diphenyl Derivatives — Styrone — Sodium Dithiosali- cylate. Thymol, Camphors, and Essential Oils : The Terpenes, their Properties and Products of Oxidation — Turpentines — Camphors — Thymol Aristol — Europhene — Menthol — Oil of Cloves, Caraway, Hops, &c. — Terehene, Oil of Eucalyptus — Camphor, Personal Use — Patents — Eucalyptol — Eucalypto- resorcin — Myrtol — Terpin Hydrate — Terpinol — Absynthol — Caryophyllin — Eugeuol — Bomeol — Various Patents — Camphoid — Combining Disinfectants with Soda Crystals — Bases of Powders — The Oxidising Power of Essential Oils — Ozone Test — Sanitas, Sanitas Oil — Value of Sanitas as a Disinfectant — Camphoric Acid — "Pinol." BENZOIC ACID GROUP. Benzoic Acid, CjIIj . CO . OH, exists in gum benzoin, balsams of Peru and Tolu, and several aromatic gums that have been used for ages for enbalming. It is made by acting on boiling toluene, CgH5(CH3), with chlorine, and oxidising the benzyl chloride, OgHg. OHjCl, with nitric acid. It melts at 121° C, boils at 250° C, but sublimes slowly with a pungent, aromatic odour, even at ordinary temperatures. It is sparingly soluble in cold water, yielding an acid solution of pungent, disagreeable taste. It acts as a stimulant, expectorant, diuretic, and is strongly antiseptic both as solid, solution,, and vapour, and even in its salts. Salkowski,* in a number of experiments with meat juice inoculated with putrid fluid, showed that benzoic acid, in a dose smaller than salicylic, prevented for a long time the putrefaction of the mixture and the development of bacteria. Bucholtz f found that 1 in 1,000 stopped the growth of micro-organisms. Haberkorn did not succeed * Veber die antisept. Wirhung d. Salicylsaure und Benzoesaure, Berlin Klin. Wochenschr., 1875, p. 22. f Archiv.f, exp. Pathol,, 1875, vol. iv. 196 DISINFECTION AND DISINFECTANTS. with the bacteria of urine with less than 1 in 400. Jalan de la Oroix,* in seventy-four experiments with varying quantities, showed that the least quantity that would prevent bacterial growth from being inoculated into a fresh liquid (beef tea) was 1 in 2,800. To kill, bacteria he required 1 in 410, and to sterilise spores 1 in 50. As regards non-organised ferments ("enzymes"), Wernitz f declares that pepsin is neutralised by 1 in 200, and others by 1 in 300, of benzoic acid or benzoate of soda. Graham Brown | stated that sodium benzoate was superior to quinine hydrochloride and sodium salicylate in destroying the virus of diphtheria ; he believed even that by saturating the human system with benzoic acid by repeated hypodermic injections, it was rendered almost insusceptible of inoculation with diphtheria. In disorders of the bladder, attended by ammoniacal urine, Gosselin and Robin § proved that benzoic acid taken internally rendered the urine acid, preventing the precipitation of insoluble phosphates, and the formation of carbonate of ammonium and poisonous salts by the urinary bacteria, and also diminished the amount of urea excreted. Therefore, Frerichs introduced it successfully for ursemia. They use 1 to 4 grammes per day dissolved in glycerine and water. Tallin states |1 that " in most cases, to destroy definitely and without return germs transplanted from a sterilised liquid into the midst of an appropriate cultui-e fluid, the proportion of benzoic acid should be 1 in 77, or even 1 in 50." This would make it rather more potent than phenol, cresol, or other similar compounds. It is not poisonous ; Prof. Senator, of Berlin, gave as much as 50 grms. of sodium benzoate a day to a patient with acute rheumatism, without ill effect. As much as 1 oz. of ammonium benzoate per day can be taken without any noticeable effect, and is excreted as hippuric acid in the urine. In those cases in which the odour and taste is immaterial, a saturated solution of benzoic acid in water delays the putrefaction of animal matters much more effectively than salicylic. It has less effect on vegetable effusions. It is also useful for preventing fats from becoming rancid. Added to milk, a very small quantity prevents coagulation.lT Benzoic acid and benzoates are ingredients in many antiseptic mixtures, as, for example, the following complex receipt : — " Anti- septic pastilles for use in diphtheria are made by incorporating boric * Aj-chiv. f. exp. Pathol,, 1881, vol. xiii., p. 175. t Dorpat Essay, 1880. t Kleb's Archiv., vol. viii., p. 140. § Arch, genirales de Mid., 1874, vol. xxiv., p. 566. || Disinfectants, p. 202. IT Horn, Zeitschr.f. Chem. Industr., vol. ii,, p. 329, 1888. ORGANIC SUBSTANCES. 197 acid and borax, each 20 grms.; citric acid, 12'5 grms.; sodium benzoate, 1 grm., with glycerine and water as solvents, and gum, sugar, and gelatine as bases, and dividing into 500 pastilles." * Dr. Miller states that by using the following mixture he could completely sterilise the mouth and cavities in carious teeth : — " Thymol 4 grains ; benzoic acid, 45 grains ; tincture of eucalyptus, 3^ drachms ; water, 25 ozs." f By heating benzoic with boracic, tartaric, or citric acid, double com- pound acids called benzo-boracic, &c., are formed, which are, of course, antiseptic, and are mentioned in some of the older patents. Although the benzoic acid is thus rendered much more soluble, and its taste is in great part disguised, it frequently crystallises out, and hence these compounds are now seldom heard of This separation also makes them irritant to wounds and mucous surfaces. Listerine contains 2 grains of benzo-boracic acid in each fluid drachm, together with the essential oils of thyme, eucalyptus, Baptisia, Oaul- iheria, and MentJia arvensis. Benzoic aldehyde, or benzaldehyd, CgHj . CO . H, occurs with hydro- cyanic acid in oil of bitter almonds. Angus Smith | considered it a little below phenol in antiseptic power. It readily oxidises to benzoic acid, is sparingly soluble (1 in 30), and is of no hygienic use except in ointments, when the crude oil is very effective against eczema, irrita- tion, and parasites, partly on account of the prussic acid it contains. Obviously the skin must not be broken. Sulphobenzoic acids, C(iH^(HS03)(00. OH), of which there are three isomers, made by the action of oil of vitriol on benzoic acid, are very soluble, and have an acid and bitter taste. They and their salts are antiseptic.§ The derivative "Saccharin," benzoyl-sulphonicimide, is also sometimes used as a preservative. It has the constitution. SOj 00/ C,H/ \NH. The mixture of sodium salts are met with as an antiseptic under the name of sodium sulphobenzoate.§ Benzanilide is a weak antiseptic used as an antifebrile. "Benzosol," or benzoyl-guaiacol, (C|.H5)CO.O(05H^.OCH8), is obtained from benzoyl chloride and sodium guaiacol. It is a crystalline powder, colourless, almost free fi-om taste and smell, insoluble in water, easily soluble ill alcohol, and melts at 50° C. It is said to combine the effects of guaiacol (p. 175) and benzoic acid without any disadvantages, and to be very useful in tuberculosis, facilitating expectoration and * Year-Booh of Pharmacy, 1889. f Oktm. and Drug., 1887, p. 83. J Disinfectants, Edinburgh, 1869. § Journ. Soc. Chem. Ind., 1888, p. 226. 198 DISINFECTION AND DISINFECTANTS. rendering the sputum free from bacilli. Prof. Sahli, however, remarks that the commercial article is of varying composition, that he found some specimens inert, and that "as the effect of guaiacol and creosote were due to local antiseptic action in the stomach, benzosol could not take their place." It is used largely in diabetes mellitus. Benzo-paracresol, CgH3(C5Hg.OO)(OHg).OH, is an antiseptic prepared by the action of sodium benzoate on paracresol (p. 164), in presence of oxychloride of phosphorus. It occurs as a crystalline powder almost insoluble in water, but soluble in alcohol (0'15 per cent.). It melts at 71° C* Benzo-naphthol, OioH70.CO(OgH5), from i3-napthol, melts at 110° C, and has also been proposed for internal antisepsis. SALICYLIC ACID. There are three isomeric oxybenzoic acids, of which only the ortho- compound, called salicylic acid, CgH^(OH).COOH, is of practical importance. It is met with in minute white needles or prisms, of pungent odour and sweet taste (inodorous when pure, Charteris), soluble in 500 parts of cold, and 15 of boiling water, in 7 of alcohol, 3 of ether, and 50 of glycerine. "When heated quickly it breaks up into phenol, which distils, and carbonic acid. The same decom- position occurs in the human system, as phenol appears in the urine. It is antiseptic and antipyretic. J. B. Duggan found that it was twice as powerful an antiseptic as the corresponding para-oxy-benzoic acid, whilst the meta-acid had intermediate properties.! "Artificial" salicylic acid (from sodium phenate and carbonic acid) is somewhat more toxic in its action than the pure " natural " acid obtained from oil of wintergreen. This is due to two foreign acids, isolated by Williams in 1878, and found by Dunstan and Blochl to be ortho- and meta-cresotic acids, C5Hg(CHg)(0H).C00H, derived from the cresols contained in the crude phenol from which the salicylic acid had been prepared. Sobering and others now prepare a pure artificial acid from pure phenol, which is free from these impurities, and acts in the same way as the natural acid. It melts at 156-7° C. It gives a purple colour with ferric salts, therefore cannot be pre- scribed with them. It is not corrosive, and does not coagulate albumen. The salicylates are much more soluble. Salts of nearly every metal have been prepared and recommended for various uses ; but sodium salicylate, OgH^(OH).OOON'a, is the most usual one. * Bevue de Chim. Indusir., April 15, 1893. t Am. Chem. Journ., vol. vii., p. 62. tJourn. Chem. Soc, April, 1891. ORGANIC SUBSTANCES. 199 Oil of Wintergreen, Gaultheria procumbens, is methyl salicylate, 05H^(OH)COO(CH3). It is a colourless, fragrant liquid, sparingly soluble in water, but easily in alcohol, and also in alkalies. Specific gravity, 1-18 ; boiling point, 222° C. Perier, of the hospital of St. Antoine, Paris, substituted this oil for phenol in surgery, using a mixture which was perfectly miscible with water : — Oil of Wintergreen 30 grammes, tincture of quillaia ■6 grammes, water 1 litre. Gosselin and Bergeron* found that the oil, both as a solution and as vapour, hindered the putrefaction of blood, and that it was neither irritant, nor of disagreeable odour. It is still used in Prance for dressings, but is inferior to phenol and other agents in power. It does not coagulate albumen, and is not poisonous. "Salol," Phenyl salicylate, OeH^(OH).000 (CgHg), is made from sodium phenol and sodium salicylate by heating with phosphorus oxychloride. It is a white crystalline powder, melting at 42° C, with a faint aromatic odour, practically tasteless, neutral, insoluble in cold water, soluble in 15 parts of rectified spirit, in 3 of ether, and very soluble in chloroform and in oils. Antipyretic and anti- septic, it passes through the stomach unchanged, to be decomposed in the duodenum into phenol and salicylic acid.f It is used in diarrhoea, dysentery, cholera, &c., as an internal antiseptic, also as an injection in gonorrhoea and cystitis. It has been employed externally as a substitute for iodoform in skin and nasal diseases. Lowenthal J has shown that salol will kill cholera bacilli in a paste containing pancreatic juice. Spirituous solutions (5 per cent.) are employed with various flavouring agents for mouth-washes and ■dentifrices, toilet-powders, and soaps. When melted with camphor, salol, like many other substances, forms a permanent liquid which has also been used to replace iodoform.§ "Salophen," 0(.H4(OH)(COO.OeH^.]SrH.CO.CH3), an imido-com- pound formed by heating salicylic acid with phosphorus oxychloride and para-nitrophenol, reducing and acetylating, resembles the preceding in properties, but is said to have rather stronger antiseptic power. M. P. 188° 0. It has not been much used, and is expensive. Cresyl Salicylates. — The three cresols form corresponding salicylates, and have been proposed as internal antiseptics. Betol, salinaphthol, or naphthosalol, is a /3-naphthol salicylate, and has already been described under Napthol (p. 179). Salbromanilide is said to be a mixture of bromacetanilide and sali- cylanilide. Salipyrin is a compound of antipyrin and salicylic acid. *Arch. g4n4ral. deM6d., 1881, p. 16. "^ Brit. Med. Journ., 1887, vol. xi, p. 1438. J Comptes Eendus, vol. cvii., p. 1169. % Repertoire, 1889, p. 185. 200 DISINFECTION AND DISINFECTANTS. Phenosalyl is a mixture of phenol, salicylic, benzoic, and lactic acids, made by heating them together at 140° C, adding menthol and euca- lyptol, and, after, cooling, adding four times the volume of glycerine. It is a clear, syrupy liquid, of sweetish taste. It is easily miscible with water or alcohol, is not poisonous, and has a pleasant and non- persistent odour, which does not cling about the hands and clothes. The solutions have no corrosive action on the skin, the mucous sur- faces remain smooth and slippery, and do not become dried up, as is the case after washing with carbolic acid or "corrosive sublimate." Of course, this latter advantage belongs to the glycerine, and would equally pertain to phenol or mercuric chloride in the same medium. Prof. Frankel,* in a series of bacteriological trials, found that pheno- salyl possessed an antiseptic power superior to phenol in dealing with the micro-organisms of cholera, anthrax, pneumonia, typhus, diph- theria, tuberculosis. Bacillus pyocyaneus, and Staphylococcus pyogenes aureus. " It is well known that the last-mentioned bacterium is one of the most resistant, but even a 1 per cent, solution of phenosalyl is sufficient to kill it, while to produce the same effect with carbolic acid one must use a SJ per cent, strength, and the exposure or contact must be continued for a longer period." Phenosalyl has been used by Duloroy in the sterilisation of instruments, of gauze, and of different organic substances like blood, as well as decomposing urine and the saliva of consumptives with most encouraging results. It does not corrode nor discolour metals under ordinary circumstances of contact. This is an example of a mixture which seems to present great advantages. Of late years there has been a tendency to use compli- cated compounds, most of them only soluble in alcohol, which, apart from expense and other faults, is inadmissible as a medium for many purposes. It should be noticed that while in mixtures the properties of the ingredients are mostly retained, in many of these compounds not only are the properties lost, but frequently new and objectionable ones are developed. For example, the desire to avoid the unpleasant odour of iodoform has led to the introduction of many "substitutes" which are costly, unstable, uncertain, and even dangerous in their action. However, phenosalyl may be reckoned as a convenient preparation of the above aromatic acids dissolved in lactic acid and glycerine, and scented with menthol and eucalyptus. The name is rather an unfor- tunate one, as leading to a wrong idea of its composition. Salicylic acid is by no means an innocent remedy. In fact it can. be a powerful poison, as it has a disintegrating action on the blood corpuscles. The salts cause albuminuria, hence, must be irritating * Bacterienkunde, BerliD, 1890. ORGANIC SUBSTANCES. 201 to the kidneys, probably through phenol being formeu.* The acid, in strong (alcoholic) solutions, or in ointments, is so caustic that it is the basis of most of the popular cures for corns.f As to dilute solutions. Dr. Bond, of Westminster Hospital, states that "when in the country he has been in the habit of taking 10 grains daily for a month without bad eiFect," obviously as an anti-malarial. The official dose of the acid is 5 to 30 grains. Dr. Brouardel has noticed daily doses of 2 grammes to produce grave symptoms of intoxication and poisoning. KolbeJ first drew attention to the antiseptic properties of salicylic acid. He showed that it prevented the action of enzymes (unorganised ferments), like diastase, emulsin, and that of mustard, also gastric digestion, fermentation by yeast, ammoniacal fermentation of urine, and the germination of seeds. H. A. Weber § and Leffman and Beam |] proved that a solution of 1 in 420 of salicylic acid, com- pletely checked salivary and pancreatic digestion of starch, and that even 1 in 840 had a marked depressing influence. As to the strength required for killing bacteria, it has been variously given by different observers. RatimofF^ uses 1 in 400, practically a saturated solution in water and a little spirit; Jalan de la Croix,** 1 in 200 for milk, and more than 1 in 35 for germs in meat juice ; Bucholtz,tt 1 in 362 ; and Kiihn, 1 in 200 for germs in albumen solution. As to salicylate of soda, the necessary dose is stated as 1 in 100 by Miquel, and 1 in 161 by Bucholtz. Vallin+J points out that "this action on ferments and microbes is. often only temporary ; the ferments and bacteria rapidly become used to their new surroundings, and the generations that succeed resist doses that had been fatal to their ancestors, and the work of fermenta- tion goes on again at the end of a few days. Neubaur and Bechanip have specially proved this curious phenomenon of the habituation of ferments to progressive doses of phenol and salicylic acid. It follows, that, to obtain a durable antiseptic effect, we must at frequent inter- vals add new and increasing doses of the agent. For this reason, in alcoholic beverages, which can only be preserved by the aid of salicylic acid, the dose of this substance sometimes reaches as much as 1'5 grammes per litre. Even then experience has shown that poor wines and ciders soon undergo fresh fermentation of acid or putrid character. * See a paper by Dr. Squire on the "Physiology and Therapeutics of Salicylic AAA," Lancet, Dec. 20, 1879. t Whelpley, Chem. and Drug., Aug. 16, 1890. J J.Jur Pract. Chem., 1874, vol. x., p. 89. § Journ. of Ame.r. Chem. Soc, 1892, p. 4. il Journ. Soc. Chem. Ind., 1888, p. 582. IT Bied. Ceuiralblatt, vol. xiv., p. 360. ** Arch. exp. Pathol., 1881. +t Ibid., 1875. 202 DISINFECTION AND DISINFECTANTS. Salicylic acid, then, is a convenient antiseptic, but it gives no absolute guarantee, and its power is limited." The very sparing solubility of salicylic acid in water has led to a variety of devices for increasing it. Alcohol is in many cases unsuit- able ; glycerine only dissolves 2 per cent.; alkalies form salicylates, which, although soluble, have only about one-third the antiseptic power of the free acid. Borax solution dissolves a large quantity of salicylic acid, forming a loosely-combined crystalline compound, in- odorous, neutral, and of little taste, called borosalicylate of soda. It is much more soluble, and is more antiseptic than either of its com- ponents (see under Boric Acid, p. 102). Offen and Moore,* "to prevent the second fermentation of yeast or ■other ferment when combined with wheat or other cereal for food," use 10 parts of salicylic acid, 3 of boric, and 4 of borax, dissolved and mixed with the grain either whole or ground ; " yeast is then added, and the dough baked as usual." Lactacidine solution contains 2 '65 per cent, lactic acid, and 0"35 per •cent, salicylic acid, " to which other materials, such as sugar or glycerine, may be added." It is used for preserving articles of food — ■e.ff., butter. It may be removed by washing before use.f Salicylic acid is largely used for preventing loss of material, and •consequent annoyance with fruit; 4 to 8 grains of the acid to the pint or lb. prevent fermentation in saccharine liquids; and jams, preserves, &c., can be kept for years. " As a preservative it is best «,pplied in process of preparation. It is advisable to gradually intro- duce it in the solid state into the boiling mass" (but it somewhat readily volatilises with the vapour of water), "constantly stirring, •or the acid may be rubbed down with the fruit juice, and then added. In any case the finished product ought not to show any white flocks." Another mode is to pour over the cold uncooked fruit the cold salicylated juice of the same fruit, so that the fruit is entirely •covered. A cold juice may be made by pressing the fruit, adding "to every pound 15 grains of the acid, heating the juice, and allowing to cool. In this way, cherries, plums, (fee, can be preserved all the winter uncooked, and are then suitable for pies. The last of the above processes seems better than the others, since almost all the ■salicylic acid can be removed by washing the fruit before cooking. Salicylic acid is very largely used for perishable articles of food. Many preparations, more particularly of salicylic and boric acids, are sold as "lard bleachers," and "fruit, wine, and cider preservatives." Most authorities agree that it is a most objectionable preservative, especially in milk which is destined for young children. Powdered * Patent No. 16,592, 1887. t GrosJiU, Patent No. 2,235, 1887. ORGANIC SUBSTANCES. 203 salicylic acid, that has been used for hams, fish, (fee, is mostly washed off, but •when mixed with, or allowed to penetrate the food, chronic dyspepsia and other symptoms would certainly be caused by the rela- tively large quantities that would accumulate in the system. There seems evidence to show that, like lead and arsenic, it has a cumulative action. Vallin,* in an exhaustive discussion of this point, shows that if a man consumes an average quantity of salicylated foods and drinks as met with in Prance (he gives tables of the amount customarily added to a number of foods) he would absorb per day 3 grammes of salicylic acid. He observes that it is nefariously used to secure the disposal of inferior articles that would not otherwise be saleable. In 1880 the French Committee of Public Hygiene, after the matter had been fully reported upon by M. Dubrisay, passed, on Feb. 7, 1881, the following edict which is still in force : — " Est interdite la -vente de toute substance alimentaire, liquids ou solide, GOntenant une quantite quelconque d'acide salicylique ou dhm de ses derives." At the present day, food arriving at the city barriers, if it should be adulterated, and especially with salicylic acid, is seized, and its owner punished. K. Portele saysf that salicylic acid cannot be considered a success as a preservative either for butter or milk, as it gives to them an unpleasant sweetish odour, which increases until decomposition takes place. H. A. Weber J and Dr. H. Vogel § strongly condemn the practice of adding preservatives to food, proving that it interferes with digestion, l^essler observes that " salicylic acid is not a natural constituent of any food, and its addition is a fraud on the quality." He, with Voge], Pasteur, and others, demanded that the addition of any quantity of this acid to wine should be mentioned on the bottle. The German Government seem to be yet undecided. In England, although a few trifling increases of fine have followed the finding of salicylic acid by public analysts in milk where there was added water also, it seems to be recognised as a customary addition to syrups and to "British wines." In a test case at the Great Mario w Petty Sessions, a grocer was prosecuted for selling raspberry wine adulterated with salicylic acid. For the defence two analysts swore that salicylic acid "was absolutely necessary to preserve the wine," and that it was " quite innocuous.'' In the result the case was dis- * Disinfectants, pp. 189 to 193. t Landw. Verstichs. Stat., vol. xxvii., p. 143. XJoum. Amer. Chem. Soc, vol. xiv., pp. 4-14. § Deutsche Viert.f. Off. Oes., 1880, p. 402. 204 DISINFECTION AND DISINFECTANTS. missed. If wines be carefully made, they can be sterilised without any drug, and will keep for a reasonable time after opening. Among special salicylic acid prejjarations the following may be noticed : — Solution for Local Antisepsis.* — Water, 1,000; boric acid, 12; sali- cylic acid, 2. In Patent No. 15,564, 1887, Boake and others show that "sodium sulphite dissolves one-sixth of its weight of salicylic acid ;'' they pro- pose to make such solutions with any|^alkaline sulphites or bisulphites for antiseptic purposes. "Stroch's Antiseptic Paper." — Seep. 142. Antiseptic Tablets. — " (1) For Thiersch's solution, much used in many modern operations, Adolph Levy, of Brooklyn, N.Y., recommends 14 grains of ' resublimed ' salicylic acid and 84 grains of pure boric acid, to be compressed into a tablet, which is dissolved when required in 16 ounces of hot distilled water, t (2) Warner & Co. make pastilles of sodium bicarbonate, biborate, benzoate, and salicylate, with menthol, eucalyptol, and oil of wintergreen. One of the pastilles gives 2 ounces of a solution to be applied as spray in nasal catarrh." " Strongly deodorant as well as antiseptic." | (3) Sacker, 79 Fenchurch Street, make tablets of similar composition, " to be each dissolved in two quarts of water." § Salicylated Gauze. — Gauze washed with soda to remove grease, then in succession with water and acidulated water, then bleached by chloride of lime and weak acid, and finally well washed with water and dried. Next soaked in a solution of salicylic acid, 5-6 parts; glycerine, 15; rectified spirit, .50; distilled water up to 100 parts; drained, nearly dried by a current of sterilised warm air, rolled or folded by machines previously made aseptic. The finished gauze is packed in cylinders freshly lined with melted paraffin sterilised by heat. The gauze is thus kept permanently slightly moist. || Contact with iron must be avoided, or purple stains result. Anisic Acid or para-oxymethyl-benzoic, CjH^(0CH3)C00H, occurs in colourless prisms, melting at 175° and distilling at 280° C. The sodium salt was recommended by Curci in 1887 as antiseptic and antipyretic, in doses of 15 grains. It was said to be analogous in action to sodium salicylate, but without disturbing influence on digestion. Cinnamic Acid, CgHj.CH : CH.COOH, also met with in prisms, is * Carcano and Cesares, Revue de Chim. Indust,, April 15, 1893. t Chem. and Drug., vol. xxxviii., 1891. J Lancet, vol. xi., 1890. § Lancet, vol. xi., 1889, p. 174. II Seward Williams, Chem. and Drug., May 27, 1893. ORGANIC SUBSTANCES. 205 more soluble; melts at 133°, toils at 290° C. It is somewhat strongly- antiseptic. Styracol or cinnamyl - guaiaeol, OeH^.OH : CH.COOCCgH^.OCHj), occurs in needle crystals ; is said to be a strong antiseptic in catarrli of the bladder and intestines, and in phthisis ; soluble in alcohol.* /3-Phenyl-propionic Acid or hydrooinnamic acid, CgHj.CHj.CHj.COOH, is formed in the decay of albuminous matter, and, like other similar products, is a bactericide. It forms fine needles, moderately soluble, melting at 47° and boiling at 280° C. Klein regards this and phenyl- acetic acid, CgH^.CHjjCOOH (sparingly soluble pearly plates, melting at 76°, boiling at 262°, strong odour of burning urine), as among the strongest of disinfectants. Laws has studied the next acid in this series (see p. 159). Gallic Acid, trioxybenzoic, OgH2(OH)g,COOH, is astringent and feebly antiseptic. It occurs in sparingly soluble inodorous needles. Tannin, gallotannic acid, 0^4^HjuOci,2H20, is an amorphous powder, usually brownish, very soluble, and strongly astringent. It is well known to precipitate gelatin, and to form a compound with skins which is imputrescible (leather). It also coagulates albumen. Therefore it is, in some sense, antiseptic, but Gosselin and Bergeron,t having added to 2 grammes of fresh blood 8 drops of a 10 per cent, aqueous solution of tannin, saw vibrios appear in the mixture on the fourth or fifth day — that is to say, almost as soon as they would without any antiseptic. Gubler and Bordier J state that a horse which for many days had received doses of 20 grammes of tannin, remained with its blood un- putrefied till the fifth day after death. There are many varieties of tannins from many different plants, but none of them have even the power to preserve their own solutions. Styrone forms silky white crystals of a sweet taste, and having an odour like hyacinths. It is soluble in 12 parts of water, and easily in alcohol. The saturated aqueous solution has been recently found in America to be a perfect deodoriser of a foul ulcerated surface, and to cause no irritation. As an antiseptic it is said to exceed thymol. This explains the healing properties long attributed to tincture of benzoin, of which liquid storax is a constituent. S.0gH3(OH).COOH Sodium Dithiosalicylate "No. 1," | , has only re- S.0eH3(OH).C0OH cently been brought under notice as a powerful antiseptic. In a 15 per cent, solution the most resistant bacilli are easily destroyed in from twelve to fifteen minutes. In a severe case of ozoena it effected * A. Haas, Sudd. Apotli. Zeit., 1891, p. 55. t Arch, de M4d., 1881, p. 16. t Bull, de TMrapeuL, 1873, vol. Ixxiiv., p. 265. 206 DISINFECTION AND DISINFECTANTS. a complete cure in a relatively short time. In 2^ to 5 per cent, solu- tion this preparation is reported to have yielded most strikingly beneficial results in the treatment of foot-and-mouth disease, in which its further trial would seem to be very desirable.* THYMOL, CAMPHORS, AND ESSENTIAL OILS. From the time of the ancients it has been known that this class of aromatic bodies had a prophylactic action against fevers, and were of value in purifying air, and as insecticides. Precious woods were those which contained essential oils, like sandal-wood and cedar ; they were used in constructions wished to be imperishable, and for boxes to contain valuable tissues and documents. They were burnt for fumiga-; tions to drive away 'diseases, they were carried about the person, they were thrown as logs into water, and mixed in wines and possets. The ancient classic wines had generally a strong resinous flavour, due to the admixture of herbs, and even to a trace of wood-tar purposely added to the grapes to check objectionable fermentation, also to bitumen on the stoppers, so that, apart from the agreeable odour, there was also a real sanitary use for perfumes. A large number of patents for disinfection contain aromatic gums and resins as adjuncts. It is well known that these were used with bitumen for embalming, and bodies have been preserved in this way. The result, however, was in great part due to desiccation and protection from the air. Musk, which seemed to give some relief in plague cases at Hong- Kong, has been successfully used in large doses for cholera by Monsiorski.f These odorous principles are divided into two classes : — Class I. — Hydeocaebons, composed of carbon and hydrogen only. They mostly belong to the terpene grotxp, Oj(,Hjg, or derivatives of it. This formula includes the liquid portions of the oils of thyme, orange, lemon, savine, turpentine, juniper, hop, cloves, camomile, and the majority of others. It will be noticed that the use of condiments may be explained on the assumption that they are all (including salt, mustard, and vinegar) antiseptic and preventive of fermentation, hence germs in the alimentary canal have their action arrested. Oils of capivi and cubebs, probably affecting micro-organisms in the urinary tract, have the polymeric formula, C;^5II2^, as proved by their vapour density. Cedrene, from cedar, is said to be CJ5H28, hence would not be a terpene. Menthene from peppermint is CjdHjg. The cause of the differences in odour of these diiferent compounds of the same formula is not yet entirely known, but in many cases the difference is due to physical isomerism. All are liquids with boiling points much *HelWng, Med. Materia Medica, p. 90. f Prov. Med. Journ., Feb., 1S94. ORGANIC SUBSTANCES. 207 higher than that of -water (mostly 160° to 180° C), yet they emit at ordinary temperature minute quantities of strongly scented vapour, and are readily volatilised with steam. Their specific gravity is usually less than that of water (0"83, orange, to 0"94, caraway), and they are almost insoluble in it ; they are readily soluble in alcohol, forming " essences," and in other hydrocarbons and in fatty oils. "When fragrant plants are distilled with water the essential oils float on the surface of the distillate, while a small proportion dissolves to^ form the "distilled waters" of pharmacy, all of which are mildly antiseptic. Both the essential and the fatty oils produce a greasy spot on paper, but the spot produced by the former gradually disappears, whereas- that of the latter remains fixed, so that the presence of adulteratior^ can be easily detected. The essential oils neither combine with, nor dissolve in, alkalies ; yet, if they be present when resins or fat are saponified, a large propor- tion remains dissolved in the soap, and is only liberated on dilution with water, when an emulsion similar to those obtained with tar oils is formed. Chlorine, bromine, and iodine act on most of the essential oils, (iodine at first merely dissolves), giving compounds in which the halogen displaces one or more atoms of hydrogen, at the same time the odour is much afi'ected, becoming gradually pungent. Excess of chlorine breaks them up entirely into hydrochloric acid and carbon. Therefore they are not suitable for use with the halogens. The antiseptic or disinfectant properties of substituted essential oils are not well known, but there is no evidence to indicate their utility. The terpenes rapidly absorb dry hydrochloric acid gas, yielding compounds called artificial camphors ; some of them are crystalline, and in appearance and properties much resemble natural camphors. Patents have been taken out for these products, but they have not hitherto been of much value. The artificial camphor obtained from. oil of turpentine is the best known. Artificial camphors are only formed from the terpenes by slow combination with water. Turpentines. — When an incision is made in a pine tree, a resinous fluid flows out, which is mainly a solution of various resins in the hydrocarbon, OjoH^g, called "oil or essence of turpentine." " Common turpentine " comes chiefly from Finus abies, " Venice turpentine " and "Bordeaux turpentine" from Finus maritima, and " Chian turpentine " from Pistacia lentiscus. They are somewhat different in antiseptic value, but different specimens vary among themselves. By distillation with water, about one-fourth (the essence) passes 208 DISINFECTION AND DISINFECTANTS. over with the steam, while three-fourths remain behind as rosin. The latter has no antiseptic power, but is used as an adjunct or medium in a large number of organic disinfectants (Jeyes, (fee). "Camphine" is the oil of turpentine from Finns australis. Letheby found that 1 in 4,000 of oil of turpentine in air prevented necrosis. Class II. — Oxidised Compounds, such as camphor, thymol, &c., are ■crystalline solids, existing dissolved in tlie natural oil, from which they either separate spontaneously or by refrigeration. They were formerly called stearoptenes. Some of them have been formed by oxidation of the hydrocarbons, others are of a different constitution, such as — Thymol, propyl-m ethyl-phenol, or propyl-metacresol, CgHg(CH3) (Cgnj)OH. By cooling oil of thyme, crystals of thymol separate, while the liquid portion consists of thymene, CjqHjj, boiling at 165° C. Oil of thyme contains about equal proportions -of thymol and thymene ; both have the pleasant odour of the plant and a hot aromatic taste. Thymol is easily fusible (melting point, 44° C), lighter than water, in which it is very sparingly soluble (3 parts in 1,000), and is easily soluble in alcohol. It does not readily combine with, or dissolve in, alkalies, and is insoluble in acids, except sulphuric, with which it unites to form thymolsulphonic acid, in almost inodorous soluble crystals whose physiological properties do not seem to have been examined. Dr. Paquet first* recommended thymol as an antiseptic in surgical dressings, and as an inhalation in pulmonary gangrene. Jalan de la Croix t found on an average that while 1 in 1,000 prevented bacteria from growing, 1 in 100 was necessary to kill them, and as much as 1 in 20 to destroy the germs. Miquel ranks it as strongly antiseptic, since 2 grammes " neutralised " a litre of beef tea. Other observers found the following strengths necessary to prevent the development of bacteria ; in urine, 1 in 3,000 {Haberhorn) ; in infusion of peas, 1 in 3,027 (Kuhn) ; in tobacco infusion, 1 in 2,000 (^Bucholtz). Wernitz states that a saturated aqueous solution (3 in 1,000) arrests pancreatic digestion. Kobert, Kohler, and Stern used it to preserve vaccine lymph, as while it prevented it from putrefying, it only slightly •diminished its activity. Koch mentions it as specially inhibitory to tubercle. Eatimoff % puts it fourth in his list of disinfectants, arranged in order of potency (mercuric chloride, silver nitrate, iodine, thymol), saying that " 1 in 35,000 killed putrefactive bacteria." * Bull, giniral de Tliirapeutique, 1868. ■'r Arcliiv. f. experim. Pathol., Jan. 20, 1881. t Bierdermann's Centralblatt, vol. xiv., p. 360. ORGANIC SUBSTANCES. 209 Thymol in a saturated solution in water arrests fermentation and putrefaction better than carbolic or salicylic acids.* Thymol gauze is used in surgery, and an ointment has been made -with lanoline. It is, however, too expensive for use on the large scale. " Listeriae " is a mixture of the essential oils of thyme, eucalyptus, Baptisia, GauUheria, and Mentha arvensis ; each fluid drachm also contains 2 grains of refined and purified benzo-boracic acid. The action of iodine on thymol is of interest. The action may be represented as follows : — CeHICCHsXCsHjlOH 2CcH3(CH3)(C3H7)OH + 3I2 = + 4HI C6HI(CH3)(C3H7)OH This compound is di-iodo-di-thymol, and is known commercially as Aristol or Annidaliae. — It is a white solid, melting at 60° C, insoluble in water, soluble easily in alcohol and ether. Like most iodine com- pounds it turns brown on exposure to light and air, liberating iodine. It is said to be strongly antiseptic. Menthol. — Oil of peppermint contains a hydrocarbon, menthene, CjQHjg, boiling at 163° C, together with a white crystalline solid obtained by cooling it, menthol, Oj^H^gHgO. Menthol melts at 34° C, and boils at 213° C. It smells of peppermint, and has antiseptic properties. Peppermint from very early ages Las had an immense repute as an arrester of fermentations. Several medical receipts for " plague water " have peppermint as a basis. In a recent cholera scare there was a ■strong demand both in Germany and England for peppermint herb, and for the oil and water. W. L. Braddon f directs attention to the antiseptic properties of oil of peppermint in diseases in which antisepsis is the best mode of treatment. Angus Smith spoke highly of it. j It was ascertained by Koch that 1 part of the oil in 300,000 arrested the development of spores, and that the vapour from warm oil of I)eppermint quickly killed both spores and bacilli. Dr. A. Macdonald found that the power of menthol is about double that of phenol — " 1 in 500 kills bacteria." § Both it and oil of thyme seem to be useful antiseptics. Oil of Cloves. — ^This is extensively used for preserving paste, gum, Ac, and for carious teeth ("Bunter's Nervine"). It is heavier than most essential oils (specific gravity 0-918), rather more soluble in water, and n)ore volatile (boiling point 143° C). All these peculi- arities increase its value as an antiseptic. It consists chiefly of a liquid terpene, CiqHj^, holding in solution eugenic acid, G^f^H^^O^ * Brit. Med. Journ., 1875, vol. i,, p. 680. t Year-Booh of Pharmacy, 1888. % Disinfectants and Disinfection, 1869. § Edin. Med. Journ., 1880, p 121. 14 210 DISINFECTION AND DISINFECTANTS. (Ettling), -with an isomer eugenin, and a variety of camphor called caryophyllin, Q^^^f). Oil ofCaratuay is yet heavier (specific gravity 0-938). It contains a. hydrocarbon carvene, Cj^Hjg, isomeric with thymol — specific gravity 0-953, boiling point 225° 0. (Voelcker). The latter yields with an alkaline solution of ammonium sulphide a peculiar substance named carvol hydrosulphide, (Oi()Hj^^O)2H2S, in yellowish crystals sparingly soluble in alcohol, almost insoluble in water, but slowly decomposed by it. It has an unpleasant odour, and is strongly antiseptic, but hardly available on account of cost, insolubility, and poisonous char- acter. Jalan de la Croix * states that 1 in 1,000 of carvol destroyed the bacteria of tobacco infusion, while 1 in 360 was required for those of urine. Oil of Cinnamon is considered by Lucas Championniere to be superior to even corrosive sublimate as an antiseptic. Oils of verbena and geranium have similar properties.t Essence of Hops is a powerful agent in checking fermentation, hence its former universal use in brewing. It readily absorbs oxygen, being converted into an acid resinous mass containing valerianic acid, CjHjj.OOOH. The main constituents are a terpene, CjgHjg, and valerol, OgHjoO. All the other essential oils are more or less antiseptic, but their general use is negatived by (1) their cost; (2) sparing solubility; (3) their persistent odour, which becomes after a time insupportable ; (4) their want of energy in terminating, as distinguished from re- straining, putrefaction and fermentation changes ; (5) internally, their injurious action on digestion. Their chief value, beyond that due to their odours and flavours, consists in their general property of hinder- ing fermentation in the alimentary canal. They are largely used for mouth washes, tooth powders, &c. Terebene, CjqHjj (specific gravity, 0-86; boiling point, 160° C), is a, liquid obtained by acting on turpentine with about one-twentieth of its weight of oil of vitriol, and distilling. It has a strong odour re- sembling that of thyme and pine-wood, oxidises less readily than' turpentine, and is only slightly soluble in water, but easily in alcohol and oils. Some years ago it was extensively commended as a " disin- fectant;" it has now almost fallen out of use except in "Terebene Soap,'' which is a pleasant preparation of some antiseptic power, con- taining 1 to 2 per cent, of terebene. Prof Maclean, of ISTetley, reported favourably on its use for surgical and sanitary purposes. Camphors.— -These are oxidised essential oils. * ArcUv.f. exp. Pathol, Jan. 20, 1881. t liev. TUrap., 1S93, p. 290. OEGANIC SUBSTANCES. 211 Ordinary or Laurel Camphor, CjoH^gO, is a white solid of specific gravity -996. About 1 per cent, dissolves in water, communicating to it, as "camphor water," its odour, with its stimulant and antiseptic properties. It is very soluble in alcohol ; the tincture in moderate doses is an irritant poison. Dr. Eubini in Naples used it largely in cholera and diarrhoea. Camphor has some repute as a personal prophylactic, but it is obvious that there cannot be sufficient of the vapour to disinfect the air. It is irritant to the skin. It burns with a luminous sooty flame ; but when burnt, either alone or with spirit, the products of combustion contain little or no camphor. Spirit lamps containing this and essential oils in spirit have often been proposed for fumigation, but are obviously of little value. There are numerous inventions relating to camphor. " Sanoscent " is a block disinfectant containing camphor, eucalyptus, pine-oil, "and other germ-killers." The basis of most of the cakes or blocks commonly met with is either naphthalene, paraffin, or plaster. " Hebden's Cam- phortar" is camphor, eucalyptus, and tar distillates, similarly made into blocks for lavatories, &c., and also recommended to be grated among clothes for insects (see under Naphtludene, p. 148). A mixture of equal parts of camphor and animal (vegetable?) charcoal is recommended by Barbocci for preventing the ofiensive odour and removing the pain (?) of old excavated ulcers.* Kyle + has shown that camphor combines in molecular proportions with menthol. Symes X has made a similar compound with menthol. These compounds, like that with phenol, are generally liquids. Hille§ suggests its use with magnesium or calciuai chloride for drains and for dressing vines. Bromo- and iodo-camphor are strongly antiseptic, but irritant. Eucalyptol, or eucalyptus camphor, CjjHjgO, was first isolated by E. Jahns from the essential oil of various species of Eucalyptus. Since then it has been detected in numerous other oils. Besides six species of Eucalyptus there are 15 plants which yield it. It is a colourless liquid, smelling like camphor, of specific gravity 0-930, boiling point 176° C, and crystallising point - 1° 0. It is practically insoluble in water, but is miscible with alcohol, ether, chloroform, and fatty oils. The Eucalyptus trees have long been famous for their anti-malarial action, and are largely planted on the Continent in marshy districts. According to Cloez, the half-dried leaves contain 6 per cent, of the oil. It is used in the antiseptic treatment of atonic * Chem. and Drug., 1887, p. 373. + Am. Journ. Pharm., 1885, p. 429.. t Pharm. Journ., 3, vol. ix p. 598, § Patent No. 6,411, 1889. 212 DISINKECTIOS AND DISINFECTANTS. ulcers, gangrene, &c., internally and by inhalation for pulmonary affections.* Candles containing 5 to 10 per cent, of oil of eucalyptus or cajeput ■with or without a little phenol were patented by Wright, f In all these fumigating appliances the greater part of the organic matter is destroyed in burning, only a fraction being volatilised unchanged, while the peculiar odour becomes after a time sickly and insupport- able. All fumigating candles, except the so-called "sulphur candles" (p. 93) and some bromine and iodine forms (p. 73), are therefore unsatisfactory. Tablets containing eucalyptus oil and chalk, which have a powerful and pleasant odour, have been introduced for domestic use. J Eucalypto-resorcin is a hard amorphous mass obtained by mixing eucalyptol with excess of resorcin in the cold. It crystallises from chloroform, is insoluble in water, but very soluble in alcohol and iii ether. It is said to have some advantages as an antiseptic. Myrtol, from essence of myrtle, is a clear liquid of pleasant odour, boiling between 160° and 180° C. Eichorst recommended it as an internal antiseptic. It is a mixture of dextro-pinene (the main hydro- carbon of turpentine, juniper, eucalyptus, and sage oils, ifcc.) with eucalyptol, and would be advisedly replaced by the latter (Jahns). Terpin Hydrate, CjQHjg(OH)2,H20, is prepared by the interaction of a mixture of 4 parts of oil of turpentine, 3 parts rectified spirit, and 1 part of nitric acid in shallow porcelain dishes during some days. It occurs in large colourless and inodorous crystals with a faint aromatic taste. On warming there is a separation of the water and formation of terpin, Cj(,Hjg(0H)2. The development of tubercle bacilli is arrested by a 0'25 per cent, solution (Colpi). It has been used internally in lung and kidney diseases (^Manasse and Talamon). " Terpineol " is the product obtained by boiling terpin or terpin hydrate with dilute mineral acids. According to "Wallach it is a mixture in variable proportions of terpineol (CjgHjgO) and several terpenes. Guelpa and Morra have proposed it as an antiseptic in cases of bronchitis. Absynthol is an isomer of camphor from oil of wormwood. Caryophyllin, CgjIIgjOg, is a polymer from oil of cloves ; Eugenol, CjQHjgOo, an unsaturated compound, being the chief constituent of the oil. Borneol or Borneo camphor, Cj^H^j^O, from Bryobalanops camphora, * See Gimbertj Eucalyptus gloiulus, and its Importance in Agriculture, Hygkne, and Medicine (Paris, Delahaye, 1S70). Demarquay in 1872 recommended euca- lyptol in surgery. Sir J. Lister has used it as a substitute for carbolic acid. t Patent No. 11,963, 1884. J Lancet, vol. xi, 1890, p. 724. ORGANIC SUBSTANCES. 213 is a white crystalline solid with an odour like pepper, resembling ordinary camphor in properties. It is slightly more antiseptic than camphor (Selmi). An "Improved Disinfecting Fluid"* consists of 28 lbs. chloride of lime, 14 lbs. of camphor, and 50 gallons of " black varnish" (a coal-tar product) mixed together. "After standing for eight days the resulting substance is ready for use in urinals, ifec." Camphoid, though in itself only feebly antiseptic, is a useful vehicle for applying more active agents to the skin, and forms a protective coating. It is a mixture of camphor, pyroxylin, and alcohol. Several so-called disinfectant washing powders have been patented. These usually consist of a mixture of disinfectants with soda crystals. R. P. Hicks t makes a saturated solution of sodium carbonate in boiling water, and then on cooling, as it crystallises, a mixture of diamylene (or decylene, CjoHj,,), oamphene (one of the terpenes, Ci^Hj,,), menthene, terebene, cymol, thymol, and sometimes phenol is added. Many of the essential oils are used as disinfecting powders. Under phenol (p. 154) the bases of the most common powders have already been mentioned. Lime, magnesia, and alkaline bases unite with the disinfectant when it has acid properties. The volatile oil is then only slowly evolved by the action of the carbonic acid of the atmo- sphere. Sand is too coarse for general use, but infusorial earth and artificial silica (Calvert), being inert bases, give off the volatile matters completely. For use in wet places, such as urinals, inorganic bases are the best ; while for stables, rooms, &c., sawdust and peat are most serviceable. Plaster of Paris and cement are sometimes used ; whilst dry earth and burnt clay are suitable for rough work. The Oxidising Power of Essential Oils. — Sanitas. — Schonbein first observed that in all slow processes of oxidation a small quantity of the oxygen is converted into ozone. This is the case in the slow burning of phosphorus. If any organic matters be present, they are rapidly oxidised by the ozone formed. He remarked that oil of turpentine and other essential oils were specially active in this way, and that ozone, probably from being continually re-formed, was permanently present in small amount as long as any oxygen was left. He attributed the purifying action of perfumes entirely to this ozonising effect. But Angus Smith % proved by experiments that the explanation v,'as not sufB.cient, and that their antiseptic action must also be taken into account. He suspended ozone paper (blotting- paper dipped in potassium iodide and starch paste) in a large flask containing a thin layer of the essential oil, and judged the amount of * Lees, Patent No. 1,738, 1893. t Patent No. 6,209, 1887. X Disinfectants, Edinburgli, 1869, p. 118. 214: DISINFECTION AND DISINFECTANTS. ozone by the degree of blueing of the paper, taking 10 degrees as an arbitrary maximum. He gives the following table : — Degree of Blueing of the Ozone Paper. After 18 hours. 24 hours. 48 hours. 72 hours. Oil of Orange-peel, Considerable. Strong Colour. 9 10 Essence of Turpentir e. Feeble. Distinct. 7 9 Oil of Juniper, . Considerable. )j 5 5 ,, Cumin, . None. None. 2 2-5 ,, Lavender, 2 2-5 Creaol, 2 2 Phenol, pure, . None. 1 Creosote (Wood), ,, None. Pyroligneous Acid, ,, »» Camphor, 3» Oil of Thyme, . ,, Naphthalene, . >J This test is not very delicate, as there is no doubt that traces of ozone are produced -with all the above compounds except naphthalene. Other observars have found oil of thyme to give more than cresol. Yet the fact is obvious that the antiseptic action is not proportional to the small quantity of ozone formed, though the slight disinfectant power may be. Although, relatively, there is only a mere trace of ozone, amounting perhaps to 1 in 1,000, nevertheless it may form a considerable quantity in a large volume of air. Scoutteten * found that ozonised air rapidly removed the odour of foul manure ; Tlichardson and Wood, that of putrid blood that had been kept in a flask for two years. Bond attributed the disinfecting action of permanganate to its production of ozone, t Boillet proved that ozone not only destroyed a putrefactive odour already formed, but actually prevented putrefaction. | Chapuis collected the germs and dust from contaminated air by filtering it through cotton wool ; he then submitted some of the wool plugs to the action of ozonised air. On then placing the wool in a nutrient solution (wort), the untreated plugs caused rapid turbidity and growth, the ozonised ones remained clear for twenty days.§ From the known fact that the hygienic condition of a locality varied with the proportion of ozone in the air as shown by test papers, and that several epidemics had been preceded by a sudden fall in ozone, he very naturally argued that ozone must have the power also of destroying pathogenic organisms. Miquel asserts that ozone attacks gaseous emanations before it acts * L'Ozone, Metz, 1856. t Comptes Rendus, 1875, p. 1258. t Brit. Med. Journ., 1875, p. 239. § Bull. Soc. Ohimique, 1881, p. 290. ORGANIC SUBSTANCES. 215 on bacteria or spores. Subsequent investigations have shown that it does attack the latter (see Ozone). Thenard was one of the first to show, and Ireland,* Barlow,t and others to confirm, that this gas is a poison, and was capable of causing asphyxia and fatal bronchitis, and that even a very minute quantity was irritant to the mucous membranes. These facts have a direct bearing on the claim of many advertised ■" disinfectants '' to give ozone. The odour of turpentine, the smell of a newly-painted house, even the proximity of a pine forest, though supposed to be good for consumption and pulmonary complaints, undoubtedly cause in many people considerable irritation of the eyes, nose, and lungs. Still, inmost cases, the freedom of the air from germs produces manifest improvement. C. T. Kingzett, about 1874, noticing that in presence of excess of warm water, peroxide of hydrogen, which is not irritant, is produced in solution rather than ozone, together with oxidation products of the terpenes, which acted as strong antiseptics, introduced a new disinfectant under the name of " Sanitas." In the first patent J turpentine oil is floated to a sufiicient depth on the surface of warm water in large jars called oxidisers, and currents of warm air or oxygen are forced through the mixture continuously for seven to ten days, maintaining the temperature con- stantly at 60°. The proportions used are 9 parts of turpentine oil to 1 of water. Berthelot has also shown that oil of turpentine is capable of dissolving from 3 to 5 per cent, of oxygen. The action in the presence of water is, therefore, of a dual character, the atmospheric oxygen molecules simultaneously producing molecules of peroxide of hydrogen, HgOg, which dissolve in the water and oxidise the turpentine, yielding camphors, camphoric acid resins, minute quantities of formic acid, cymene, ifec, and a substance named by Kingzett "camphoric peroxide." Part of these dissolve in the water, part remain in the oil. The products are : — 1. " Sanitas fluid," of a light straw colour and pleasant aromatic odour. It contains camphoric acid, camphoric peroxide, and gives a distinct purple reaction with sulphuric acid and potassium bichromate, showing the presence of hydrogen peroxide, amounting, according to the Lancet, to such a proportion that twice its volume of oxygen is given off when it is decomposed. 2. " Sanitas oil," a brown syrupy liquid, lighter than water, and insoluble in it, but soluble in alcohol, and having a similar odour to * Annates de Bygi&ne, vol. xix., p. 439. + Joum. of Anat. and Physiol., 1S79. J No. 274, 1876. '216 DISINFECTION AND DISINFECTANTS. that of the liquid. When shaken with water, the latter acquires a peroxide of hydrogen reaction which is not so strong as that produced by the fluid.* It burns like camphor with a sooty flame. Patent No. 5,572, 1882, added resin and resin oil, and camphor or thymol. Turpentine, oil of eucalyptus, and "camphor oil" are also among the ingredients used. The " Sanitas air purifier " consists of fine wood flour impregnated with camphoric peroxide. A Sanitas toilet soap is made, and soft soaps, veterinary washes, and emulsions of the oil with gums, &c. Patent ISTo. 1,589, 1890 (Kitigzett), refers to " oxidised turpentine mixed with soft or hard soap." In patent No. 276, 1887, it is proposed to use : — 1. Tin instead of earthenware for storing, as Sanitas is not corrosive to metals. 2. Sea water instead of ordinary water, as the hydrogen peroxide keeps better in a saline solution. 3. " One or more antiseptics added before or after oxidation." Horgreaves t mixes Sanitas oil and other disinfectants with laundry blue for linen. Dr. A. B. Griffiths, in testing the germicidal powder of the various Sanitas preparations, and particularly of " Sanitas oil " as liquid and vapour, on the bacilli, of diphtheria, tuberculosis, glanders, cholera, typhoid, and scarlet fever, found that : — 1. "One-tenth per cent, of the oil was incapable of destroying the microbe of typhoid in bouillon, but 1 per cent, prevented its develop- ment." 2. "One-quarter per cent, completely destroyed Micrococcus scarlatincB in nutrient gelatine, J per cent, prevented its development (six tubes in each case)." 3. "Eight tubes, each containing 100 c.c. of nutrient gelatine, were inoculated with Bacillus diphtherice from pure sub-cultures of the microbe; and after three weeks' incubation at 20° C, h c.c. of Sanitas oil was added to each tube, and the incubation continued four days. As a result, the microbes in all the tubes were found to have been destroyed, as animals susceptible to diphtheria on being inoculated were unaffected." 4. " The bacilli of tuberculosis and of glanders were destroyed respectively by 1 per cent, in six, and by ^ per cent, in seven days." 5. "The spirilla of Asiatic cholera (Koch) in ten tubes of bouillon (slightly alkaline) were killed in five days by 1 per cent, of the oil. It was further demonstrated that it is quite impossible to inoculate gelatine plate cultivations containing 1 per cent, of Sanitas oil with * Lancet, vol. i., 1890, p. 809. + Patent No. 2,524, 1883. ORGANIC SUBSTANCES. 217 the microbe of cholera ; although when Sanitas was absent the microbes gave rise to colonies." 6. An apparatus was fitted by which the vapour of Sanitas oil from a flask heated to 100° C. in a water bath was passed into test-tubes con- taining nutrient media in which the above-mentioned organisms were growing. They were all destroyed in from four to fifteen minutes. From this it is concluded that the vapour itself possesses genuine germicidal powers, and should be of service in the treatment of diseases of the throat and lungs. It must be remembered, however, that these are not quite the conditions under which the agent would be employed in practice ; the bacterial growths seem to have been at or near the surface of the nutrient gelatine, instead of having pene- trated deeply into the tissues. No mention is made as to whether any water was placed in the flask with the oil ; the vapour of a fluid with so high a boiling point as Sanitas oil seems hardly likely to pass over at the temperature of boiling water except in the presence of steam. Dr. Bond, of Gloucester,* Dr. Poehl,t and Mr. Kingzett himself | have placed " Sanitas " and its varieties in the very first rank of disinfectants. On the other hand, Vallin§ says that the statements should be accepted with reserve, admitting, however, that " this product, being unknown in France, we have not been able to experiment on its efiicacy.'' Harding Crowther|| points out that equal parts of vaccine lymph and Sanitas fluid did not prevent the inoculation succeeding. It might therefore be used as a preservative. Tripe and Stevensonll and Longstaff and Hare,** after numerous experiments, arrived at the conclusion that " the Sanitas fluid and powder do not disinfect better than slaked lime;" they recognise, however, that this substance retards putrid decomposition, but that "it is little active in deodorising substances already putrid." It is obvious that Sanitas, like some other preparations, has suffered by being over extolled ; its chief points of interest are : — ■ 1. The "fluid" is non-poisonous, non-corrosive, and does not stain. 2. It certainly oxidises most organisms and their products when in sufficient quantity and strength, say 1 or 2 parts per 100. 3. In antiseptic power it is about equal to the cresol preparations and superior to the carbolic ; over both it has the advantage, shared * Brit. Med. Journ., 1875, p: 239. t Revue d'hygiene, 1879, p. 510. J Sanitary Becord, 1879, p. 370, and 1880, p. 348. § Disinfectants, 1882, pp. 177 and 316. || Med. Times and Gaz., 1879, p. 361. ^ Med. Times and Gaz., 1880, p. 51, "Disinfectants in contradistinction to Deodorants and Antiputrefactive agents." ** Sanitary Record, 1878, p. 353. 218 DISINFECTION AND DISINFECTANTS. with permanganate and the halogens, of chemical destruction of the microbes and of exhalations. 4. Its action on sulphuretted hydrogen is not great, that on ammonia is almost nil. It can, however, be used with an absorbent like chloride of zinc, but not with ferrous sulphate, sulphurous acid, or other re- ducing agents. 5. Its price is decidedly higher than some other disinfectants if quantity required be considered. A " Sanitas water-cart block, con- sisting of Sanitas in a highly concentrated (solid) state," intended to he placed inside the cart for disinfecting streets, has been proposed, but it is more than doubtful whether this could be done efiiciently ■except at a prohibitive cost. 6. It is valuable for toilet use when a persistent odour is not an •objection. Many people find it very agreeable. It ranks about equal to sodium hypochlorite (liquor sodse ohlorinata, p. 63). 7. More evidence as to its stability or constancy of composition is required. 8. Further independent investigations as to its efficacy in epidemics like typhus, cholera, &c., as to the poisonous dose of " Sanitas oil,'' and whether it has irritant external effects, seem also desirable. Kingzett calculates that the eucalyptus forests of New South Wales and South Australia alone contain, at any moment, sufficient oil in the leaves, ready to be evaporated into the atmosphere under the agency of warm winds, to form no less than about 93 million tons of peroxide of hydrogen, and 507 million tons of camphoraceous prin- -ciples.* A fluid called " Pinol " is advertised, derived from Pinus pumilo. It Tesembles other terpene preparations, but is somewhat more pleasant in odour. We have no experience of its efficiency. The Wandsworth Chemical Works manufacture "the Pineotas series," including fluid, oil, sawdust, and soap, also carbolic prepar- ations, sheep dips, &c.t * Social Science Congress, Manchester, 1879 ; also see the same author's Nature's Hygiene. t For further chemical information as to the terpenes and their derivatives, see ■0. Wallach, Liebig's Annalen, vols, ccxxvii., coxxx., ccxxxix., ecxlvi., &c., also on essential oils, ka., Journ. Soc. Ghem. Ind., 1888, p. 226. On cresols, Frauklaud and Ward's Second Report, abridged in Journ. Soc. Chem. Ind., 1893, pp. 1,051-3. On phenol and camphor in antiseptic dressings, see Gosselin and A. Bergeron, Comptes Rendus, Sept. 29, 1879, " Experiments on the Behaviour of Blood mixed with known quantities of Phenol, Alcohol, and Camphorated Spirit." COMPOUNDS RELATED TO THE ALCOHOLS. 219 CHAPTER XI. COMPOUNDS RELATED TO THE ALCOHOLS. Methyl Alcohol : Wood Spirit — Methyl Chloride — Chloroform — Methene Bi- chloride. Formic Aldehyde or "Formalin": its Properties and Disinfectant Value — Action on Bacteria — Other Aldehydes. Ethyl or Ordinary Alcohol : Not a Reliable Antiseptic except when Concentrated — Higher Alcohols — Acetone. Formic Acid and Sodium Formate. Acetic Acid : Aromatic Vinegar — Acetic Acid as a Poison — Pyroligneous Acid^Aoetates. Glycerine : its Uses — Glycerine Soaps — Preservation of Food. Oleic Acid, Oils, and Fats: Lanolin. Petroleum: Hexane— Vaseline. Vegetable Acids : Tartaric, Citric, Malic, Oxalic, Succinic. Methyl Alcohol, CHg.OH, is a colourless liquid closely resembling ethyl alcohol, but boiling at a lower temperature, 66° C. In the crude form of wood spirit it has long been used to preserve anatomical specimens, owing its efficiency in great part to the creosote,