GHEMI 5 TRY 
 
) 
 
THE CHEMISTRY 
 
 OF 
 
 COOKING AND CLEANING 
 
 A MANUAL FOR HOUSEKEEPERS 
 
 BY 
 
 ELLEN H. RICHARDS 
 
 Instructor in Chemistry, Woman's Laboratory, 
 Massachusetts Institute of Technology, 
 Boston 
 
 BOSTON 
 ESTES & L AU RI AT 
 
 3OI 305 WASHINGTON ST 
 
 18S2 
 
Copyright ^ 1881. 
 BY ESTES & LAURIAT. 
 
PREFACE. 
 
 JN this age of applied science, every opportunity 
 of benefiting the household should be seized 
 upon. 
 
 The family is the heart of the country's life, and every 
 philanthropist or social scientist must begin at that 
 point. Whatever, then, will enlighten the mind, and 
 lighten the burden of care, of every housekeeper will be 
 a boon. 
 
 At the present time, when the electric light and 
 the gas stove are familiar topics, there is, after all, no 
 branch of science which might be of more benefit to 
 the community, if it were properly understood, than 
 Chemistry — the Chemistry of Common Life. John- 
 ston's excellent book with that title deserves a wider 
 circulation, and a more careful study. 
 
viii 
 
 PREFA CE. 
 
 But there is a space yet unoccupied for an elemen- 
 tary work which shall give to non-scientific readers 
 some practical information as to the chemical com- 
 position of articles of daily use, and as to their action 
 in the various operations in which they are employed. 
 
 The public are the more ready for the application 
 of this knowledge since Chemistry is taught in nearly 
 all High Schools, and every child has a dim idea of 
 what some part of it means. To gather up into a 
 definite and practical form these indistinct notions is 
 the aim of this little book. 
 
 There is, lingering in the air, a great awe of chem- 
 istry and chemical terms, an inheritance from the age 
 of alchemy. Every chemist can recall instances by 
 the score in which manufacturers have asked for 
 recipes for making some substitute for a well-known 
 article, and have expected the most absurd results to 
 follow the simple mixing of two substances. Chemicals 
 are supposed by the multitude to be all-powerful, and 
 great advantage is taken of this credulity by unscrupulous 
 manufacturers. 
 
 The number of patent compounds thrown upon the 
 market under fanciful and taking names is a witness 
 
PREFACE. 
 
 ix 
 
 to the apathy of housekeepers. It is time that they 
 should bestir themselves for their own protection. A 
 little knowledge of the right kind cannot hurt them, 
 and it will surely bring a large return in comfort and 
 economy. 
 
 These mysterious chemicals are not so many or so 
 complicated in structure but that a little patient study 
 will enable any one to understand the laws of their 
 action, as far as they are concerned in the common 
 operations of the household. 
 
 No attempt is here made to cover the whole ground 
 of chemical science, but only to explain such of its 
 principles as are involved in the raising of bread, and 
 in a few other common processes. 
 
CONTENTS. 
 
 Chap. Page. 
 I. Introduction, , , r 
 
 II. Starch, Sugar, and Fat, as Food. . . 16 
 
 III. Nitrogenous Food and t' e Chemistry 
 
 of Nutrition, 37 
 
 PART II. 
 
 I. The Chemistry of Cleaning, . . . 55 
 II. Chemicals for Household Use, . . .80 
 
CHAPTER I. 
 
 INTRODUCTION. 
 
 E recognize substances, as we know people, 
 
 by their characters (properties) and by 
 their appearance. Sugar we call sweet ; if any- 
 thing is sour, we call it acid. Sugar and salt 
 dissolve in water. Carbonic acid gas will extin- 
 guish the flame of a candle. These are proper- 
 ties of the several substances. A teaspoonful of 
 sugar heated over a fire turns black, swells up 
 to a large bulk, emits a gas which burns with a 
 smoky flame, and finally there is left a black, 
 crumbly mass, which seems like what it is, fine 
 charcoal. There is nothing which we consider 
 sugar left, no sweetness, none of the properties 
 which we know under the name of sugar. There 
 
2 
 
 THE CHEMISTRY OF 
 
 is a change, a loss of identity. This change is 
 called a chemical one. 
 
 Add a solution of an acid to a solution of 
 an alkali, and observe that the acid substance and 
 the alkaline substance are no longer in existence 
 as such. There is, instead, a neutral saline sub- 
 stance dissolved in water. The new substance 
 has not the properties of either of the others. 
 The acid and the alkali have both lost their 
 identity. A chemical change, then, involves a loss 
 of identity. 
 
 " We must be very careful not to transfer our 
 ideas of composition, drawn chiefly from the mix- 
 tures we use in common life, directly to chem- 
 istry. In these mixtures the product partakes, to 
 a greater or less degree, of the character of its 
 constituents, which can be recognized, essentially 
 unchanged, in the new material. In all instances 
 of true chemical union and decomposition, the 
 qualities of the substances concerned in the pro- 
 cess entirely disappear, and wholly different sub- 
 stances with new qualities appear in their place."* 
 
 * "The New Chemistry." — Josiah P. Cooke. 99. 
 
COOKING AND CLEANING. 3 
 
 All the substances about which we know any- 
 thing are composed of a few elementary bodies. 
 The grain of wheat, the flesh of animals, the 
 dangerous poison, all are capable of being sep- 
 arated into the simple substances of which they 
 are composed. The chemical element is that 
 substance out of which nothing essentially differ- 
 ent * has ever yet been obtained. Pure gold is 
 an element, a simple substance, from which nothing 
 can be taken different from itself. A gold coin 
 contains a little copper or silver, or both, and is 
 not pure gold; it is a mixture of two or more 
 elementary substances. The oxygen in the air is 
 an element, a single thing. Water is a compound 
 of two elements, oxygen and hydrogen, which are 
 gases when they exist as simple substances. 
 
 There are about seventy of these elementary 
 substances known to the chemist ; about ten or 
 twelve of them enter into the compounds which 
 we use in the kitchen. The others are found only 
 in the chemical laboratory or in the physician's 
 medicine case, and a few are so rare as to be 
 
 * "Treatise on Chemistry."— Roscoe & Schorlemmer. p. 51. 
 
4 
 
 THE CHEMISTRT OF 
 
 considered curiosities. Most of these elements 
 unite with each other, and, in the compounds thus 
 formed, other elements may exchange places with 
 those already there, so that a few elementary 
 bodies, by the variety of combination, make up 
 the objects of daily use. 
 
 To understand something of the nature of these 
 chemical substances and their common forms is 
 a necessity for every housekeeper who would not 
 be cheated of her money and her time. 
 
 It is important for every one to remember that 
 laws govern all chemical changes ; for one is often 
 asked to believe that some chemical sleight of hand 
 can make one pound of washing-soda worth as 
 much as two, and that some special preparation 
 of flour will give a third more bread than any 
 other. 
 
 As has been said, we recognize substances by 
 their properties, and the chemical elements have 
 two essential characteristics which must be con- 
 sidered at the outset of our discussion. 
 
 It is assumed that they are composed of homo- 
 geneous particles, the so-called atoms, the smallest 
 
COOKING AND CLEANING. 
 
 5 
 
 masses of matter which enter into chemical com- 
 bination. The particles have a definite weight, 
 constant for each substance. This weight is known 
 in chemistry as the atomic weight. 
 
 Hydrogen being the lightest substance yet known, 
 its atomic weight is taken as the unit. 
 
 TABLE I. 
 
 NAME. SYMBOL. ATOMIC WEIGHT. 
 
 Hydrogen H i 
 
 Sodium (Natrium) Na 23 
 
 Calcium Ca 40 
 
 Oxygen O 16 
 
 Carbon C 12 
 
 The atom of oxygen weighs 16, and the atom of 
 calcium 40 times as much as the atom of hydrogen. 
 The letters or symbols in chemical formulse rep- 
 resent this definite weight, so that while the word 
 oxygen means only that collection of properties 
 to which we give the name, the letter O in a 
 formula indicates also 16 times the weight of H, 
 which is taken as 1. 
 
 These symbols give a definiteness to the chemical 
 
6 
 
 THE CHEMISTRY OF 
 
 terms which words merely cannot convey, and 
 therefore they are a great aid to the right com- 
 prehension of the laws of combination. In a table 
 at the end of the book will be found the atomic 
 weight of all the elements referred to in the text. 
 
 The atoms of each element have also their own 
 value in uniting and exchanging places with the 
 others. 
 
 The unit of value is an arbitrary standard. Some- 
 thing else might have been taken than the unit 
 chosen, but the relative value of all the elements 
 as compared with each other is constant. 
 
 At the outposts of the Hudson's Bay Territory 
 all trade is on a system of barter or exchange, and 
 a basis of value is necessary. The skin of a beaver 
 is agreed upon as the unit from which to count 
 all values. For example : a red fox skin is worth 
 two beaver skins, a silver fox skin is worth 
 four beaver skins. All of the hunter's stock is 
 valued in this way, and also articles to be purchased 
 are valued by the same standard, a knife is pur- 
 chased for four beaver skins, a gun is worth three 
 silver fox or twelve beaver skins. Chemists have 
 
COOKING AND CLEANING. 7 
 
 agreed upon a unit of value in exchange, and the 
 unit thus agreed upon is the atomic weight of 
 hydrogen above referred to ; that is, the smallest 
 relative weight of hydrogen known to enter into 
 combination with other elements. It is, in a sense, 
 an arbitrary choice, but having once accepted it 
 as the unit, we can count all other values, in union 
 or in exchange, from its value. 
 
 TABLE II. 
 
 NAME. SYMBOL. 
 
 Sodium (Natrium) Na 
 Calcium Ca 
 Oxygen O 
 Carbon C 
 
 NUMBER OF ATOMS OF 
 HYDROGEN 
 WHICH THE ATOM OF 
 THE SUBSTANCE WILL RE- 
 PLACE IN COMPOUNDS. 
 
 For the convenience of the reader, this exchange- 
 able value will be indicated by the numbers over 
 the letters in the formulae given in this book, 
 although the practice is not universal. 
 
 The chemist has constructed a sign language, 
 based upon these two properties of the elements, 
 which aids the mind in grasping the idea of 
 
8 
 
 THE CHEMISTRY OF 
 
 chemical changes. The symbols are, as it were, 
 the chemist's alphabet. 
 
 The non-scientific reader is apt to look upon 
 the acquisition of this sign language as the 
 school-boy regards the study of Chinese — as the 
 work of a lifetime. While this view might not 
 be so very far from the truth, if one were to 
 attempt to remember all the symbols of the com- 
 plicated compounds which are possible in the 
 union and interchange of the seventy or more 
 elements, yet the properties and combinations of 
 the dozen of them which make up the common 
 substances of daily use are not beyond the reach 
 of the busy housewife, and can be comprehended 
 in a few hours of thoughtful reading. "To mas- 
 ter the symbolical language of chemistry, so as to 
 fully understand what it expresses, is a great step 
 towards mastering the science."* 
 
 Hydrogen seems to be the connecting link be- 
 tween the other elements, which may, for our 
 present purpose, be divided into two classes, as; 
 shown in 
 
 * " The New Chemistry." p. 149. 
 
COOKING AND CLEANING. 9 
 
 TABLE HI. 
 
 Some elements which can 
 
 be substituted for 
 H, and for each other in 
 chemical compounds. 
 
 Sodium 
 
 Potassium 
 
 Calcium 
 
 EXCHANGE 
 VALUE. 
 I 
 
 Na i 
 
 II 
 
 Ca 2 
 Hydrogen 
 
 Some elements which unite 
 
 with H, and with 
 Class I., as well as with 
 each other. 
 
 EXCHANGE 
 VALUE. 
 
 Chlorine 
 
 Oxygen 
 
 Carbon 
 I 
 
 H ] 
 
 I 
 
 CI 
 
 II 
 
 o 
 
 IV 
 
 C 
 
 I I II 
 
 H unites with CI, and forms HC1, or muriatic 
 I I 
 acid. K exchanges places with H, and the new 
 
 ill ii 
 compound is KC1. H 2 unites with O, and forms 
 
 1 ii 1 I 
 H 2 0, or water. K 2 exchanges places with H 2 , 
 
 I II IV 
 
 and the new compound is K 2 0. C unites with 
 
 II IV II 
 
 2 and forms C0 2 , carbon dioxide, or carbonic 
 
 IV II I II 
 
 acid gas. C0 2 unites with H 2 0, and becomes 
 
 I IV II I 
 
 H 2 C0 3 , or carbonic acid in solution. Na 2 ex- 
 1 
 
 changes places with H 2 , and the new compound 
 
10 
 
 THE CHE MIS TR T OF 
 
 I IV II 
 
 is Na 2 C0 3 , or commercial soda ash, the compound 
 
 with which the laundress is familiar, under the 
 
 name of washing crystal. 
 
 The letters mean always the smallest relative 
 
 quantity known to combine with anything else, 
 
 and when the elements combine in more than 
 
 one proportion, we indicate it by writing two 
 
 i i 
 
 times or three times the units. Thus H 2 or 2H 
 means twice the unit value of H. 
 
 Some of the compounds formed by the union 
 of the elements given in the Tables are very 
 familiar substances. 
 
 I ir 
 
 H 2 Water. 
 
 1 x 2, 16 Two parts by weight of hydrogen. 
 
 Sixteen parts by weight of oxygen. 
 1 O will unite with 2 H. 
 
 II II 
 
 Ca O Quick-lime. 
 
 40, 16 Forty parts by weight of calcium. 
 
 Sixteen parts by weight of oxygen. 
 1 Ca will exchange places with 2 H. 
 
 IV II 
 
 C O2 Carbonic acid gas. 
 
 12, 16 x 2 Twelve parts by weight of carbon. 
 
 Thirty-two parts by weight of oxygen. 
 
COOKING AND CLEANING. 11 
 
 The exchanges and interchanges of the ele- 
 ments according to these two laws of value and 
 weight are chemical reactions, and the expres- 
 sion of them is called a chemical equation. A 
 certain modicum of chemical arithmetic is essen- 
 tial to the right understanding of these reactions. 
 
 " In the laboratory we never mix our materials 
 at random, but always weigh out the exact pro- 
 portions . . . for, if the least excess 
 of one or the other substance over the propor- 
 tions indicated is taken, that excess will be wasted. 
 It will not enter into the chemical change." * 
 
 In the economy of nature nothing is lost. The 
 wood and coal burned in our stoves do not 
 vanish into thin air, without adding to its weight. 
 Twelve lbs. of coal (not counting the ash), in 
 burning, take 32 lbs. of oxygen, and there are 
 formed 44 lbs. of carbonic acid gas. 
 
 In all chemical equations there is just as much 
 in weight represented on the one side of the 
 sign of equality (=) as on the other. 
 
 * "The New Chemistry." /. 151. 
 
12 
 
 THE CHEMISTR 2' OF 
 
 For instance, in the equation 
 
 ii i i ii ii i II 
 
 HC1 + NaHO = NaCl -f H a O 
 
 Muriatic Caustic Sodium Water. 
 Acid. Soda. Chloride or 
 
 Salt. 
 
 36.5 + 40 = 58.5 + 18 
 
 76.5 = 76.5 
 
 The sum of the weights of the two substances 
 taken is equal to the sum of the weights of the 
 two new substances formed as the result of the 
 reaction. 
 
 The present science of chemistry may be said 
 to date from the discovery of the law of definite 
 proportions, which gave a firm basis for all cal- 
 culations. If we wish to obtain 44 lbs. of car- 
 bonic acid gas (carbon dioxide), we can tell 
 just how much pure charcoal must be taken, by 
 writing out the reaction thus : 
 
 IV 1 IV 11 
 
 C + o 2 = co 2 
 
 The atomic weight of Carbon is 12, X 1 = 12 
 The atomic weight of Oxygen is 16, X 2 = 32 
 
 44 
 
 Therefore 12 lbs. of charcoal must be burned 
 in order to obtain 44 lbs. of carbonic acid gas. 
 
COOKING AND CLEANING. 
 
 13 
 
 This law of definite proportion by weight can- 
 not be too strongly emphasized. It is the inva- 
 riable rule of chemical action, and it will be 
 referred to again and again in discussing the 
 chemical changes occurring in cooking and in 
 digestion. 
 
 When more than two elements enter into com- 
 bination, it is common for two or more to band 
 together, and in this case the group has an 
 exchange value of its own, which is not the sum 
 of the values of the separate elements, but which 
 is constant, and dependent upon these values in 
 a way which it is not necessary to explain here. 
 
 These partnerships will be included in brackets 
 II ii i 
 as (S0 4 ) (C0 3 ) (N0 3 ), not that these letters 
 
 represent actual compounds existing by themselves, 
 
 I 11 IV 11 11 1 
 as do H 2 0, C0 2 , CaG 2 , but that the group en- 
 closed in the brackets passes from one compound 
 into another as if it were only one element, and 
 the numbers over the^ bracketed letters will indi- 
 cate the exchange value of the partnership, not 
 of the elements separately. A few illustrations 
 will serve to make this clearer. 
 
14 
 
 THE CHEMISTRY OF 
 
 TABLE IV. 
 
 Mineral Acids and Compounds : 
 
 Till I II I II 
 HC1 H(N0 3 ) H 2 (S0 4 ) H 2 (C0 3 ) 
 
 Muriatic. Nitric. Sulphuric. Carbonic 
 I I I I II II II II 
 
 NaCl K(N0 3 ) Ca(S0 4 ) Ca(C0 3 ) 
 
 Salt. Saltpetre. Plaster of Marble. 
 
 Paris. 
 
 Reactions and Equations : 
 
 I II II II II II I II 
 
 H,(S0 4 ) + Ca(CO :t ) = Ca(S0 4 ) -f H 2 (C0 3 ) 
 
 I II II I II II 
 
 H 2 (S0 4 ) + 2(NaCl) = Na 2 (S0 4 ) -f 2(HC1) 
 
 I II II I I II II 
 
 H 2 (S0 4 ) + NaCll =NaH(,S0 4 )+ HC1 
 
 It will be seen that the groups do not sep- 
 arate, but that they combine with the single 
 elements by the same law as that which governs 
 the combinations of the simple substances. 
 
 It is also to be observed that where two atoms 
 
 of hydrogen can be replaced in a compound, as 
 i II 
 
 in 11 2 (S0 4 ), either one or both can be exchanged 
 for an atom of equal replacing value, and the 
 two compounds thus formed will differ in their 
 properties. This will be shown later on, in the 
 case of cream of tartar. 
 
OF COOKING AND CLEANING. 
 
 For a full and clear exposition of the principles 
 of the science, the reader is referred to " The 
 New Chemistry," by J. P. Cooke. 
 
CHAPTER II. 
 
 STARCH, SUGAR, AND FAT, AS FOOD. 
 
 'YyHEREVER there is life, there is chemical 
 change, and as a rule a certain degree of 
 heat is necessary, in order that chemical change 
 may occur. Vegetation does not begin in the colder 
 climates until the air becomes warmed by the 
 heat of spring. When the cold blasts of winter 
 come upon the land, vegetation ceases. If plant 
 Life is to be sustained during a northern winter, 
 artificial warmth must be supplied. This is done 
 by keeping up a furnace or stove heat. In 
 chemical terms, carbon from coal, wood, or gas 
 is caused to unite with the oxygen of the air to 
 form carbonic acid gas, and by this union of two 
 elements, heat is produced : 
 
 16 
 
COOKING AND CLEANING. 17 
 
 IV II IV II 
 
 C + o 2 = C o 2 . 
 In wood and gas there is another compound 
 which is utilized : 
 
 IV I II IV II I II 
 
 CH 4 -f 4 == C0 2 -f 2 H 2 0. 
 
 These two chemical reactions express the changes 
 
 which cause the production of artificial heat used 
 
 for domestic purposes. 
 
 As many animals live in temperatures in which 
 
 plants would die, it is evident that they must 
 
 have some source of heat in themselves. This 
 
 is found in the union of the oxygen of the air 
 
 breathed, with the carbonaceous matter eaten as 
 
 food, and the formation of carbonic acid and 
 
 IV 11 I II 
 
 water (C0 2 and H 2 0), just as in the case of the 
 
 combustion of the wood in the grate. Only, in- 
 stead of this union taking place in one spot, and 
 so rapidly as to be accompanied by light, as in 
 the case of the grate fire, it takes place in each 
 drop of the fluid circulating in the body, and so 
 slowly and continuously as not to be noticed. 
 Nevertheless the chemical reaction seems to be 
 identical. 
 
18 
 
 THE CHE MIS TR T OF 
 
 The first condition of animal life to be studied 
 is, then, that portion of the food which supplies 
 the heat necessary for the other chemical changes 
 to take place. The class of foods which will be 
 here considered as those for the production of 
 animal heat, includes carbon compounds, chiefly 
 composed of carbon, hydrogen, and oxygen. 
 
 These carbonaceous bodies need abundance of 
 oxygen for their slow combustion or oxidation, 
 and hence the diet of the animal must include 
 fresh air, — a point too often overlooked. It does 
 not make a bright fire to pile on the coal 
 without opening the draught. 
 
 A certain quantity of heat is produced by other 
 causes than' this combustion of carbon compounds, 
 which will be considered later, but the best 
 authorities seem to now agree that the chief heat- 
 producing foods used by the human race include 
 starch, sugar, and fat. 
 
 Starch is the first in importance, both from its 
 wide distribution and its extensive use. Starch is 
 found in all plants in greater or less abundance. 
 It is laid up in large quantities in the seeds of 
 
COOKING AND CLEANING. 19 
 
 many species. Rice is nearly pure starch, wheat 
 and the other cereals contain sixty to seventy 
 per cent of it. Some tubers contain it, as pota- 
 toes, although in less quantity, ten to twenty per 
 cent. It is formed from the carbonic acid gas 
 and water contained in the air, by means of the 
 living plant-cell and the sun's rays, and it is 
 the end of the plant life, the stored energy of the 
 summer, prepared for the early life of the young 
 plant another year. 
 
 Common sugar, cane-sugar, is found in fruits 
 and the juices of some plants. It is directly or 
 indirectly a product of plant life. The chemical 
 transformations of starch and sugar have been 
 very carefully and scientifically studied, with refer- 
 ence to brewing and wine-making. 
 
 Several of the operations concerned necessitate 
 great precision in respect to temperature and 
 length of time, and these operations bear a close 
 analogy to the process of bread-making by means 
 of yeast. The general principles on which the 
 conversion of starch into sugar, and sugar into 
 alcohol, are conducted, will therefore be stated as 
 
20 
 
 THE CHEMISTRY OF 
 
 preliminary to a discussion of starch and sugar as 
 food. 
 
 There are two distinct means known to the 
 chemist, by which this change can be produced. 
 One is by the use of acid and heat, which 
 changes the starch into sugar, but can go no 
 farther. The other is by the use of a class of 
 substances called ferments, some of which have 
 the power of changing the starch into sugar, and 
 others of changing the sugar into alcohol and 
 carbonic acid gas. These substances are in great 
 variety, and the germs of some of them are always 
 present in the air. 
 
 A substance is formed in sprouting grain which 
 is called diastase, or starch converter, which first 
 changes the starch into sugar or glucose, under 
 the influence of warmth, as is seen in the pre- 
 paration of malt for brewing. The principal 
 chemical . change is expressed by the following 
 re-action : 
 
 IV I II I II IV I II 
 
 C 6 H 10 O a -f H 2 O + ferment = C 6 H 12 O e 
 Starch. Water. Sugar (glucose). 
 
 The sugar formed from starch is one of the 
 
COOKING AND CLEANING. 21 
 
 class of sugars commonly called glucose. These 
 
 sugars differ in some of their properties from 
 
 ordinary cane sugar, but cane sugar is easily 
 changed into glucose : 
 
 IV I II I II IV I II 
 
 C, a H M 0„ + H 2 O + ferment — 2 C 6 H 12 O e 
 Cane Sugar. Water. Glucose. 
 
 So, whether we start with starch or cane-sugar, 
 glucose is produced by one kind of fermentation, 
 and this glucose is then converted by yeast into 
 alcohol and carbonic acid. In beer, the alcohol 
 is the product desired, but in bread-making the 
 chief object of the fermentation is to produce 
 carbonic acid to puff up the bread, the alcohol 
 escapes in the baking. 
 
 IV 1 11 
 
 iv 1 11 
 
 2 Co H G O 
 
 C 6 H 12 Oe= J IV A n h ° l 
 Dextrose. ) 2 C 2 
 
 ^ Carbonic Acid Gas. 
 
 The alcohol, if burned, would give carbonic 
 acid gas and water. 
 
 IV I II II IV II I II 
 
 2 C 2 H 6 0+ 12 O = 4 C0 2 + 6H 2 
 
 Alcohol. Oxygen. Carbonic Water. 
 
 Acid Gas. 
 
 It will be seen that the total number of atoms 
 
22 
 
 THE CHEMISTRY OF 
 
 of carbon remains constant. There are six in the 
 starch, and 2+4=6 in the carbonic acid gas 
 at the end, and but two atoms of hydrogen have 
 been added, while 13 atoms of oxygen have been 
 required; hence, 16 lbs. of starch will yield 
 26 lbs. of carbonic acid gas and 10.8 lbs. 
 of water, more than double the weight of the 
 starch. These products of decomposition are 
 given back to the air in the same form in 
 which those substances existed from which the 
 starch was originally formed. 
 
 The same cycle of chemical changes goes on 
 in the human body when starchy substances are 
 taken as food. Such food, moistened and warmed 
 in the mouth, becomes mixed with air, by reason 
 of the property of the saliva to form froth, also 
 it is impregnated with ptyalin, a substance which 
 can change starch into sugar, as can the diastase 
 of the malt. The mass then passes into the stomach, 
 and the change once begun, goes on. As soon as 
 the sugar is formed, it is absorbed into the circula- 
 tory system and is in some manner oxidized, 
 changed into carbonic acid gas and water. 
 
COOKING AND CLEANING. 23 
 
 No starch is used in the human system as such; 
 it must undergo this transformation into sugar be- 
 fore it can be absorbed. Whatever of it passes out 
 of the stomach unchanged, meets a very active 
 converter in the pancreatic juice. If grains of 
 starch escape these two agents, they leave the 
 system in the same form as that in which they 
 entered it. 
 
 The cooking of pure starch as rice, farina, etc., 
 requires little explanation. The starch grains are 
 prepared by the plant to keep during a season of 
 cold or drought, and are very close and compact; 
 they need to be swollen and distended by moisture 
 in order that the chemical change may take place 
 readily, as it is a law that the finer the particles, 
 the sooner a given change takes place. For in- 
 stance, powdered alum will dissolve in water much 
 sooner than a crystal of alum, or marble-dust in 
 acid sooner than a piece of marble. Starch grains 
 may increase in bulk twenty-five times in process 
 of hydration. 
 
 The cooking of the potato and other starch- 
 containing vegetables, is likewise a mechanical 
 
24 
 
 THE CHEMISTRY OF 
 
 process very necessary as a preparation for the 
 chemical action of digestion ; for raw starch has 
 been shown to require a far longer time and 
 more digestive power than cooked starch. Little 
 change can take place in the mouth when the 
 starch is not heated and swollen, and in case the 
 pancreatic secretion is disturbed the starch may 
 not become converted at all. 
 
 The most important of all the articles of diet 
 which can be classed under the head of starch 
 foods is bread. Wheat bread is not solely starch 
 but it contains a larger percentage of starch than 
 of anything else, and it must be discussed under 
 this topic. 
 
 Bread of some kind has been used by man- 
 kind from the first dawn of civilization. During 
 the earlier stages it consisted chiefly of powdered 
 meal and water, baked in the sun, or on hot 
 stones. This kind of bread had the same char- 
 acteristics as the modern sea-biscuit, crackers and 
 hoe-cake, as far as digestibility was concerned. 
 It had great density, it was difficult to masticate, 
 and the starch in it presented but little more 
 
COOKING AND CLEANING, 25 
 
 surface to the digestive fluids than that in the 
 hard compact grain, the seed of the plant. 
 
 Experience must have taught the semi-civilized 
 man that a light porous loaf was more digestible 
 than a dense one. Probably some dough was 
 accidentally left over, until fermentation had set in 
 and the possibility of porous bread was thus sug- 
 gested. 
 
 The ideal loaf, light, spongy, with a crispness 
 and sweet pleasant taste, is not only aesthetically, 
 but chemically, considered the best form in which 
 starch can be presented to the digestive organs. 
 The porous condition is desired in order that as 
 large a surface as possible shall be presented to 
 the action of the chemical converter, the ptyalin 
 of the saliva. There is also a better aeration in 
 the process of mastication. 
 
 Very early in the history of the human race, 
 leavened bread seems to have been used. This 
 was made by allowing flour and water to stand 
 in a warm place until decomposition had well set 
 in. A portion of this dough was used to start 
 fermentation in fresh portions of flour and water 
 
26 THE CHEMISTRY OF 
 
 to be made into bread. This kind of bread had 
 to be made with great care, lest lactic acid and 
 other bodies, unpleasant to the taste, should be 
 formed. 
 
 Because of this disagreeable taste, and because 
 of the possibility that the dough might reach 
 the stage of putrid fermentation, chemists and 
 physicians sought for some other means of ren- 
 dering the bread light and porous. The search 
 began almost as soon as chemistry was worthy 
 the name of science, and one of the early 
 patents bears the date 1837. A good deal of 
 time and thought has been devoted to the per- 
 fecting of unfermented bread ; but since the 
 process of beer making has been universally 
 introduced, yeast has been readily obtained, and 
 is an effectual means of giving to the bread a 
 pleasant taste. Since the chemistry of the yeast 
 fermentation has been better understood, a change 
 of opinion has come about, and nearly all scien- 
 tific and medical men now recommend fermented 
 bread. 
 
 The chemical reactions concerned in bread raising 
 
COOKING AND CLEANING. 27 
 
 are identical with those in beer making. To the 
 flour and warmed water is added yeast, a sub- 
 stance capable of causing the alcoholic fermenta- 
 tion. The yeast begins to act upon the starch 
 at once, especially if the dough is of a semifluid 
 consistency, but no change is evident to the eye 
 for some hours, as the formation of sugar gives 
 rise to no other products : 
 
 But as soon as the sugar is decomposed into 
 alcohol and carbonic acid gas, the latter product 
 makes itself known by the bubbles which appear 
 and the consequent swelling of the whole mass. 
 
 It is the carbonic acid gas (carbon dioxide) 
 which causes the sponge-like condition of the loaf 
 by reason of the peculiar tenacity of the gluten, 
 one of the constituents of wheat. It is a well- 
 known fact that no other kind of grain will make 
 
 IV I II I II IV I II 
 
 C 6 H 10 O 5 + H 2 = C 6 H 12 O s 
 
 Starch. Water. Sugar. 
 
 IV I II 
 
 Carbonic Acid Gas. 
 
28 
 
 THE CHEMISTRY OF 
 
 as light bread as wheat. It is the right propor- 
 tion of gluten (a nitrogenous substance to be 
 considered later), which enables the light loaf to 
 be made of wheat flour. 
 
 The production of carbonic acid gas is the end 
 of the chemical process, the rest is purely me- 
 chanical. The kneading is for the purpose of 
 rendering the dough elastic by a spreading out 
 and thorough incorporation of the already fer- 
 mented mass with the fresh flour. 
 
 Another reason for kneading is, that the bubbles 
 of gas may be broken up into as small portions 
 as possible, in order that there may be no large 
 holes, but only very fine ones, evenly distributed 
 through the loaf, when it is baked. 
 
 The temperature at which the dough should be 
 maintained during the chemical process, is the 
 most important point. A lesson can be learned 
 from the distillers of spirit. The best temperature 
 for the first stage of the alcoholic fermentation 
 is 70 to 75 F., the maximum is 82 to 90 . 
 Above 90 , the production of acetic acid is liable 
 to occur. 
 
COOKING AND CLEANING. 29 
 
 IV I II II IV I II I II 
 
 C 2 H 6 O -f- 2 = C 2 H 4 2 + H 2 O. 
 
 Alcohol. Acetic Acid. 
 
 The more dense the dough, the more yeast is 
 needed. After the dough is stiffened by the fresh 
 flour and is nearly ready for the oven, the tem- 
 perature may be raised to 160 or 165 F., the 
 temperature of the beer mash. A quick change 
 then occurs which is so soon stopped by the heat 
 of the oven, that no time is allowed for souring. 
 
 In the use of leaven, the lactic fermentation 
 is liable to take place, because sour dough often 
 contains a ferment different from ordinary yeast, 
 and this produces a different set of reactions. 
 
 The temperature should be carefully regulated, if 
 light and sweet bread is desired. The baking of 
 the loaf has for its object to kill the ferment, 
 to heat the starch sufficiently to render it easily 
 soluble, to expand the carbonic acid gas and 
 drive off the alcohol, and to form a crust which 
 shall have a pleasant flavor. The oven must be 
 hot enough to raise the temperature of the inside 
 of the loaf to 212 F. The most favorable tem- 
 perature for baking is 400 to 550 F. 
 
30 
 
 THE CHE MIS TR T OF 
 
 The brown coloration of the crust, which gives 
 a peculiar flavor to the loaf, is probably caused 
 by decomposition due to the high heat. Some 
 dextrine may be formed. One hundred pounds of 
 flour are said to make from 126 to 150 pounds 
 of bread. This increase of weight is due to the 
 incorporation of water, very possibly by a chem- 
 ical union, as the water does not dry out of the 
 loaf as it does out of a sponge. 
 
 The bread seems moist when first taken from 
 the oven, and dry after standing some hours, but 
 the weight will be found nearly the same. It is 
 this probable chemical change which makes the 
 difference, to delicate stomachs, between fresh bread 
 and stale. A thick loaf is best eaten after it is 
 twenty-four hours old, although it is said to be 
 " done," when ten hours have passed. Thin biscuits 
 do not show the same ill effects when eaten hot. 
 The bread must be well baked in any case, in order 
 that the process of fermentation may be stopped. 
 
 The expansion of water or ice into 1700 times 
 its volume of steam is sometimes taken advantage 
 of in making snow-bread, water gems, etc. It 
 
COOKING AND CLEANING. 31 
 
 plays a part in the lightening of pastry and of 
 crackers. 
 
 Air, at 70 , expands to about three times its 
 volume at the temperature of a hot oven, so that 
 if air is entangled in a mass of dough, it gives 
 a certain lightness when the whole is baked. This 
 is the cause of the sponginess of cakes made with 
 eggs. The viscous albumen catches the air and 
 holds it, even when it is expanded, unless the 
 oven is too hot, when the sudden expansion is 
 liable to burst the bubbles and the cake falls. 
 
 As has been said, the production of the porous 
 condition, by means of carbonic acid, generated in 
 some other way than by the decomposition of 
 starch, was the study of practical- chemists for 
 some years. Among the first methods proposed, 
 was one undoubtedly the best theoretically, but 
 very difficult to put in practice, viz., the liberation 
 of carbonic acid gas from bi-carbonate of sodium, 
 by means of muriatic acid. 
 
 I 1 iv 11 11 
 
 Na H C 3 + H CI = 
 
 Soda. Hydrochloric 
 Acid. 
 
 II I II IV 
 
 = Na CI -f- H 2 O + C O a 
 
32 
 
 THE CHEMISTRY OF 
 
 The difficulty lies in the fact that this libera- 
 tion of gas is instantaneous on the contact of the 
 acid with the soda, and only a skilled hand can 
 mix the bread and place it in the oven without 
 the loss of much of the gas. Tartaric acid (the 
 acid phosphates), sour milk (lactic acid), vinegar 
 (acetic acid), alum, all of which have been used, 
 are open to the same objection. Cream of tartar 
 is the only acid substance commonly used which 
 does not liberate the gas by simple contact in 
 the cold. It unites with soda only when heated, 
 because it is very slightly soluble in cold water. 
 For the even distribution of the gas by thorough 
 mixing, cream of tartar would seem to be the 
 best. The chemical reaction is shown in the table 
 on page But as, beside gas, there are other 
 
 products which remain behind in the bread, in 
 the case of all the so-called baking powders, 
 the healthfulness of these residues must be con- 
 sidered. 
 
 Common salt, the residue from the first-men- 
 tioned reaction, is the safest, and perhaps the 
 residues from acid phosphate are next in order. 
 
COOKING AND CLEANING. 33 
 
 The tartrate, lactate, and acetate of sodium are 
 not known to be especially hurtful. As the im- 
 portant constituent of Seidlitz powders is Rochelle 
 salt, the same compound as that resulting from the 
 use of cream of tartar and soda, it is not likely 
 to be very deleterious, taken in the small quantities 
 in which even habitual " soda-biscuit " eaters take 
 it. 
 
 The various products formed by the chemical 
 decomposition of alum and soda are possibly the 
 most injurious, as the sulphates are supposed to 
 be the least readily absorbed salts. Taking into 
 consideration the advantage given by the insolubility 
 of cream of tartar in cold water, and the com- 
 paratively little danger from its derivative, Rochelle 
 salt, it would seem to be, on the whole, the best 
 substance to add to the soda in order to liberate 
 the gas ; but the proportions must be chemically 
 exact, according to the reaction given. At least, 
 there must be no alkali left, for a reason which 
 will be given under the head of hindrances to 
 digestion. 
 
 Hence, baking powders prepared by weight 
 
34 
 
 THE CHEMISTRY OF 
 
 and carefully mixed, are a great improvement on 
 the teaspoonful measured by guess. The reactions 
 of the various baking powders with the proportions 
 of each will be given on page 
 
 Another group of substances which, by their slow 
 combustion or oxidation in the animal body, yield 
 carbonic acid gas and water, and furnish heat to 
 the system, comprises the animal fats : as, for 
 instance — suet, lard and butter; and the vegetable 
 oils, as olive oil, the oily matter in corn, oats, etc. 
 
 These fatty materials all have a similar compo- 
 sition, containing when pure only carbon, hydrogen, 
 and oxygen. They differ from starch and sugar 
 in the proportion of oxygen to the carbon and 
 hydrogen, there being very little oxygen relatively 
 in the fatty group, hence more must be taken from 
 the air for their combustion. 
 
 Ci8 H36 O2 C6 H10 O5 
 
 Stearine in Suet. Starch. 
 
 One pound of starch requires one and two-tenths 
 pounds of oxygen, while one pound of suet requires 
 about three pounds of oxygen for perfect combus- 
 tion. At the same time, a greater quantity of heat 
 
COOKING AND CLEANING. 35 
 
 can be obtained from the fats, pound for pound, 
 than from starch or sugar; hence, people in Arctic 
 regions require fat. 
 
 A most noticeable difference between the starch 
 group and the fat group, is that the latter is stored 
 up in the system against a time of need. This is 
 the more easily done, since the fats do not seem 
 to undergo any essential change in order that they 
 may be absorbed. They pass the mouth and stomach 
 without any chemical change, and only when they 
 encounter the bile and the other intestinal juices, 
 is there any question as to what happens. 
 
 With these fluids, the bile especially, the fats 
 form emulsions in which the globules are finely 
 divided and rendered capable of passing through 
 the membranes into the circulatory system. The 
 change, if any, is not one destructive of the proper- 
 ties of the fatty matters. The globules are carried 
 along by the blood, and deposited wherever needed, 
 to fill up the spaces in the muscular tissue, and 
 to serve as a reserve supply of fuel. 
 
 There seems to be good reason for believing 
 that the animal does derive some fat from the 
 
36 THte CHEMISTRY OF COOKING, ETC. 
 
 other constituents of its food, but it is not an 
 important question in the diet of mankind, for 
 even the rice eaters use butter or oil with their 
 food. 
 
 It must not be inferred from what has been said 
 that the oxidation of starch and fat is the only 
 source of heat in the animal body. A certain 
 quantity is undoubtedly derived from the chemical 
 changes of the other portions of food, but the 
 chemistry of these changes is not yet fully under- 
 stood. 
 
CHAPTER III. 
 
 NITROGENOUS FOOD AND THE CHEMISTRY OF NUTRITION. 
 
 JN the previous chapter, the food necessary for 
 the existence of the adult animal was con- 
 sidered ; but animals do more than exist, they 
 move and exert force, in mechanical terms they 
 do work • also the young animal grows. 
 
 For growth and work, something else is needed 
 beside starch and fat. The muscles are the in- 
 struments of motion and they must grow and be 
 nourished, in order that they may have power. 
 The nourishment is carried to them by the blood 
 corpuscles. We find in these, as well as in mus- 
 cular tissue, an element which we have not here- 
 tofore considered, nitrogen. We find it also in the 
 products of their decomposition, hence we reason 
 
 37 
 
38 
 
 THE CHEMISTRY OF 
 
 that if the wear and tear of the muscles causes 
 the liberation of nitrogenous compounds, which 
 pass out of the system as such, this loss must 
 be supplied by the use of some kind of food 
 which contains nitrogen. Starch and fat do not; 
 therefore they cannot furnish it to the blood. 
 
 The typical food of this class is albumen, white 
 of egg ; hence the terms albuminous and albuminoid 
 are often used as descriptive of the group. The 
 other common articles of diet containing nitrogen 
 are the casein of milk, the musculine of animal 
 flesh, the gluten of wheat, and the legumen of 
 peas and beans. The proportion of the element 
 in each is shown in the table on page 53. 
 
 The chemical changes which these bodies un- 
 dergo are not well understood. The nitrogenous 
 food is finely comminuted in the mouth, because, 
 as before stated, chemical action is rapid in pro- 
 portion to the fineness of division ; but it is in 
 the stomach that the first chemical change occurs. 
 
 The agents of this change are the pepsin and 
 the acid of the gastric juice ; the two together 
 render the nitrogenous substance soluble and dia- 
 
COOKING AND CLEANING. 39 
 
 lysable, capable of passing through the membranes. 
 Neither seems able to do this alone, and it 
 does not seem to matter what acid is present so 
 long as it is acid and just acid enough ; but if the 
 acid is neutralized, action ceases ; hence the danger 
 of soda biscuit with too much soda. 
 
 The chemical changes which go on after the 
 albumen is taken into the system are not known. 
 A decomposition of some sort takes place, and the 
 nitrogen passes out of the system in urea, being 
 separated by the kidneys, as carbonic acid gas is 
 by the lungs. 
 
 The effect of cooking upon nitrogenous food 
 should be such as will render the substance more 
 soluble, because in this case digestibility means 
 solubility. Therefore white of egg (albumen) and 
 curd of milk (casein), when hardened by heat, 
 must not be swallowed in lumps. 
 
 In the case of flesh, the cooking should soften 
 and loosen the connecting tissue, so that the little 
 bundles of fibre, which contain the nutriment, may ^ 
 fall apart easily when brought in contact with the 
 teeth. Any process which toughens and hardens 
 
40 
 
 THE CHEMISTRY OF 
 
 the meat should be avoided. The cooking of 
 beans and all leguminous vegetables should soften 
 and loosen the compact grains. Hard water should 
 be avoided, as an insoluble lime or magnesia com- 
 pound of legumen is formed. 
 
 We have now considered the three classes of 
 food under one or more of which all staple articles 
 of diet may be placed — the starch food, the fats and 
 the nitrogenous material. Some general principles of 
 diet, indicated by science, remain to be discussed. 
 
 One of the most obvious questions is : Which is 
 best, — starch or fat, beans and peas, or flesh? 
 As to starch or fat, the question has been answered 
 by experience, and science has only tried to explain 
 the reason. The colder the climate the more fat 
 the people eat. The tropical nations live chiefly 
 on starch foods, as rice. From the statements on 
 page 50, it will be seen that this is right ; fat yields 
 more heat than rice. Therefore the inference is 
 plain that in the cold of winter fat is appropriate 
 food, while in the heat of summer rice or some 
 other starch food should be substituted. 
 
 No such evident rule can be seen in the case 
 
COOKING AND CLEANING. 41 
 
 of the albuminous foods. At most, the class can 
 be divided into three groups. The first includes 
 the material of vegetable origin, as peas, lentils, 
 and the gluten of wheat. The second comprises 
 the white of egg and the curd of milk, material of 
 animal origin. The third takes in all the animal 
 flesh used by mankind as food. 
 
 Considering the question from a purely chemical 
 standpoint, without regarding the moral or social 
 aspects of the case, two points stand out clearly : 
 ist. If the stored-up vegetable matter has required 
 the force derived from the sun to prepare it, the 
 tearing apart, and giving back to the air and earth, 
 the elements of which it was built up, will yield 
 so much force to whatever tears it down ; but a 
 certain amount of energy must be used up in 
 this destruction. 2nd. If the animal, having accom- 
 plished this decomposition of the vegetable, and 
 appropriated the material, is killed, and the pre- 
 pared nitrogenous food in the form of muscle is 
 eaten by man, then no force is necessary to render 
 the food assimilable ; it is only to be dissolved 
 in order that it may enter into the circulation. 
 
42 
 
 THE CHE MIS TR T OF 
 
 The force-producing power is not lost ; it is 
 only transferred to another animal body. Hence 
 the ox or the sheep can do a part of man's 
 work for him in preparing the vegetable food for 
 use, and man may thus accomplish more than he 
 otherwise could. There is, however, another side 
 to this question. Nearly all, if not all, young 
 animals live on food of animal origin. The young 
 of the human race live on milk, but it has been 
 found by experience that milk is not the best 
 food for the adult to live upon to the exclusion 
 of all else. It is not conducive to quickness of 
 thought or general bodily activity. 
 
 This fact, with many others, leads us to the 
 conclusion that mankind needs some vegetable 
 food. Two other facts sustain this inference. The 
 digestive organs of the herbivorous animals form 
 fifteen to twenty per cent, of the whole weight 
 of the body. Those of the carnivorous animals 
 form five to six per cent., those of the human 
 race about eight per cent. The length of the 
 canal through which the food passes bears about 
 the same relation in the three classes. A mixed 
 
COOKING AND CLEANING. 43 
 
 diet seems to be indicated as desirable by every 
 test which has been applied, but the proportions 
 in which the vegetable and animal food are to be 
 mingled, as well as the relative quantities of car- 
 bonaceous and nitrogenous material which will give 
 the best efficiency to the human machine are not 
 so easily determined. 
 
 Dietaries, based upon experience and chemical 
 analysis, have been prepared for soldiers' rations, 
 and for use in prisons. Many cook-books and 
 most works on physiology give lists of quantities. 
 
 One who has studied the question for years 
 says : " Not only the age and occupation, but 
 also the individuality of the person play an im- 
 portant part in the regulation of diet, and decide 
 not only the quantity but also the kind of the 
 food, and the form in which it is to be taken . . 
 For the proper assimilation of the nourishment and 
 its complete effect in the organism, the food must 
 be agreeable ; it must relish . . A supply of 
 needful nourishment is not enough. Man requires 
 yet more. He must find his food pleasing to the 
 taste . . The boiling and roasting of food 
 
44 
 
 THE CHE MIS TR T OF 
 
 materials are operations which we find only among 
 civilized people, and they have been developed 
 with the advance of civilization. The whole art 
 of cooking amounts to this : So to prepare the 
 food that it will best answer its end."* 
 
 The nutrition of the animal body, that is, the 
 assimilation of the food taken, is dependent upon 
 absorption. Absorption is dependent upon pre- 
 vious chemical processes. These processes are 
 contingent upon the secretions, the saliva, the 
 gastric juice, etc. ; and it is a well-known fact 
 that the flow of these liquids is, lo a great ex- 
 tent, under the control of the nerves. Whatever 
 excites the nerves pleasantly, causes an abundant 
 secretion of the chemical agents of food change. 
 In this fact lies the secret of modern cooking, the 
 judicious use of condiments. 
 
 Pettenkofer (Konig, page 21) says of condi- 
 ments : " I may compare them to the right use 
 of lubricants for an engine, which indeed cannot 
 replace the steam power, but may help it to a 
 
 * Die menschlichen Nahrungs-und Genussmittel, von Dr. J. Konig. 
 Berlin, 1880. 100. 
 
COOKING AND CLEANING. 
 
 45 
 
 much easier and more regular action, and besides, 
 prevent quite naturally the wearing out of the 
 machine. In order to be able to do this, one 
 condition is absolutely essential : the lubricant must 
 not attack the machine, it must be harmless " 
 
 Cooking has thus become an art worthy the 
 attention of intelligent and learned women. The 
 laws of chemical action are founded upon the law 
 of definite proportions, and whatever is added 
 more than enough, is in the way. The head of 
 every household should study the condition of her 
 family, and tempt them with dainty dishes if that 
 is what they need. If the ashes have accumulated 
 in the grate, she will call" a servant to shake them 
 out so that the fire may burn. If she sees that 
 the ashes of the food previously taken are clog- 
 ging the vital energy of her child, she will send 
 him out into the air, with oxygen and exercise to 
 make him happy, but she will not give him more 
 food. 
 
 Nature seems to have made provision for the 
 excess of heat, resulting from the oxidation of 
 too much starch or fat, by the ready means of 
 
46 
 
 THE CHEMISTRY OF 
 
 evaporation of water from the surface, this loss of 
 water being supplied by drinking in a fresh sup- 
 ply, which goes, without change, into the circu- 
 lation. The greater the heat, the greater the 
 evaporation ; hence the importance of water as an 
 article of diet must not be overlooked. For an 
 active person, the supply has been estimated at 
 three quarts per day. Water is the heat regulator 
 of the animal body. 
 
 While dangerous disease seldom seems to result 
 from eating an excess of starch or fat, because 
 the portion not wanted is rejected as so much 
 sand, many of the most complicated disorders 
 do result from an excess of nitrogen diet. 
 
 The readiness with which such substances undergo 
 putrefaction, and the many noxious products to 
 which such changes give rise, should lead us to 
 be more careful as to the quantity of food. 
 
 A growing person needs about one part of 
 nitrogenous food to four of starch and fat; a grown 
 person, one part nitrogenous food to five or six 
 of starch and fat. A fair average ration per day 
 is perhaps : 
 
COOKING AND CLEANING. 47 
 
 Bread 
 
 i lb. 10 oz. 
 
 Fat 
 
 to 2 OZ. 
 
 Rice (cooked) 
 
 Flesh 
 
 h lb. 
 h lb. 
 
 All processes of cooking and the use of all con- 
 diments which hinder digestion should be avoided. 
 Woody fibre or cellulose, as bran, irritates the 
 digestive canal, and causes it to empty itself of 
 the food before the chemical change is complete. 
 An excess of sugar sometimes decomposes with 
 the formation of acids which have the same effect. 
 
 Tannin, tobacco, salt in excess, and alcohol, all 
 harden the albuminous part of the food, and by 
 this means hinder solution. 
 
 Certain substances, as alcohol and coffee, lessen 
 the amount of food needed for the time being. 
 
 The fats 'all decompose at about 300 F., into 
 various bodies, some of them exceedingly acrid 
 and irritating to the mucous membrane of the nose 
 and throat, and which must also prove offensive 
 to the lining of the stomach. This is probably the 
 reason why many people cannot bear food fried 
 in fat, • 
 
48 
 
 THE CHEMISTRY OF 
 
 In counting the cost of the several articles of 
 diet, not only the price per pound, but the digesti- 
 bility must be taken into account. 
 
 It has been found by experiment that of the 
 total starch in rice less than one per cent, is 
 rejected, while in potatoes nearly eight per cent, is 
 not used. (See table, page 52). 
 
 The cost of a diet which derives all the nitrogen 
 from the animal kingdom has been estimated in 
 Germany as 9.2 marks per day; while an entire 
 vegetable diet, giving the same chemical con- 
 struction, is given at 1.95 marks per day. This 
 is a very evident reason why the working people 
 of all lands (except America) live on vegetable 
 food almost entirely. 
 
COOKING AND CLEANING. 
 
 49 
 
50 
 
 THE CHEMISTRY OF 
 
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COOKING AND CLEANING. 
 
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52 
 
 THE C HEM IS TR T OF 
 
 Digestibility of some articles of food shown 
 by the per cent, of the several constituents re- 
 jected : 
 
 
 Nitrogen. 
 
 Fat. 
 
 Starch Matter. 
 
 Maize 
 
 15-5 
 
 17-5 
 
 3-2 
 
 Rice 
 
 20.4 
 
 7-i 
 
 •9 
 
 Potatoes 
 
 32.2 
 
 3-7 
 
 7.6 
 
 Macaroni 
 
 17.I 
 
 5-7 
 
 1.2 
 
 Yellow Beets 
 
 39-o 
 
 6.4 
 
 18.2 
 
 White Bread 
 
 18.7 
 
 
 .8 
 
 Roast Meat 
 
 2-5 
 
 21. 1 
 
 
 Eggs 
 
 2.9 
 
 5-o 
 
 
 Milk 
 
 7.0 
 
 7.i 
 
 
 Butter 
 
 "•3 
 
 2.7 
 
 
 Bacon 
 
 12. 1 
 
 17.4 
 
 
 It has been estimated (Moleschott) that a work- 
 ing man needs daily 130 grms.* of nitrogenous 
 food and 448 grms. of non-nitrogenous food, starch, 
 fat, etc. 
 
 The following table shows the weights of the 
 different kinds of food which must be eaten in 
 order that the required quantity may be obtained : 
 
 * 28 grms. = 1 ounce nearly. 
 
COOKING AND CLEANING. 
 
 For 
 130 grms. 
 Nitrogenous 
 
 Substances. 
 
 Cheese 33® 
 
 Lentils 49 1 
 
 Peas 58 2 
 Beans " Acker- 
 
 bohnen " 590 
 
 Ox Flesh 614 
 
 Eggs 968 
 
 White Bread 1,444 
 
 Corn " 1,642 
 
 Rice 2,562 
 
 Rye Bread 2,875 
 
 Potatoes 10,000 
 
 For 
 
 448 grms. 
 Non-nitrogenous 
 Substances. 
 
 Rice 57 2 
 
 Maize 625 
 
 White Bread 631 
 
 Lentils 806 
 
 Peas 819 
 Beans " Acker- 
 
 bohnen " 823 
 
 Eggs 90 2 
 
 Rye Bread 930 
 
 Cheese 2,011 
 
 Potatoes 2,039 
 
 Ox Flesh 2,261 
 
 Daily Rations in grms. 
 
 Albuminous 
 
 [(nitrogenous) Starch Mineral 
 
 Food. Fat. Food. Salts. Water. 
 
 Soldier's Ration 
 
 (ordinary) 119 5 6 485 
 Soldier's Ration 
 
 (very rich) 116 209 40° 
 
 Working Men 148 87 526 30 2858 
 
 (Mean of estimates by 12 different authorities.) 
 
54 THE CHEMISTRY OF COOKING, ETC. 
 
 The daily need of a woman is counted as 
 three-fourths or four-fifths that of a man. 
 
 Elementary Composition in 
 
 # of C. H. 
 
 0. 
 
 N. S. 
 
 Vegetable Albumen c^.i 7.2 
 
 20.5 
 
 17.6 T.6 
 
 Egg " 534 7-o 
 
 22.4 
 
 15.7 1.6 
 
 Flesh (Fowl) 53.18 7.03 
 
 .48 
 
 15-75 i-56 
 
 Casein (Curd of Milk) 53.5 7.05 
 
 .88 
 
 15.77 -8 
 
 Of 100 parts of food (solid 
 
 and liquid) taken, 
 
 is discharged : 
 
 
 
 By the Intestines 
 
 6.7 
 
 per cent. 
 
 " " Kidneys 
 
 49-3 
 
 (< (< 
 
 " " Skin and Lungs 
 
 42.6 
 
 << <( 
 
PART II. 
 
 CHAPTER I. 
 
 THE CHEMISTRY OF CLEANING. 
 
 ^^"EXT to the materials for food, those used for 
 the very necessary operations of cleaning are 
 perhaps of greatest interest to the housekeeper. 
 
 This chapter will discuss the properties of the 
 chemical substances which are suited to aid in 
 performing the work of cleansing to the best 
 advantage. 
 
 First in importance among these chemical ma- 
 terials are soap and its substitutes. 
 
 " Whether the extended use of soap be preceded 
 or succeeded by an improvement in any com- 
 munity — whether it be the precursor or the result 
 of a higher degree of refinement amongst the 
 
 55 
 
50 
 
 THE CHE MIS TR T OF 
 
 nations of the earth — the remark of Liebig must 
 be acknowledged to be true, that the quantity of 
 soap consumed by a nation would be no inaccurate 
 measure whereby to estimate its wealth and civiliza- 
 tion. Of two countries with an equal amount of 
 population, the wealthiest and most highly civilized 
 will consume the greatest weight of soap. This 
 consumption does not subserve sensual gratification, 
 nor depend upon fashion, but upon the feeling of 
 the beauty, comfort and welfare attendant upon 
 cleanliness ; and a regard to this feeling is coin- 
 cident with wealth and civilization." * 
 
 It is surely a problem of the greatest interest to 
 every housekeeper, how to keep her household 
 and its belongings in a state of cleanliness that 
 shall be a state of perfect health ; for a large 
 portion of disease is a direct result of uncleanly 
 ways. [The toleration of impure air in close rooms 
 is one of the most common, as well as one of the 
 most easily remedied of these uncleanly ways.] 
 
 This state of cleanness must also be attained 
 at the least cost in money, time and labor. Such 
 
 * Muspratt's Chemistry as applied to Arts and Manufactures.^ 
 
COOKING AND CLEANING. 57 
 
 a question ought to stir the business capacity of 
 every woman in charge of a house. As we have 
 said, soap and its substitutes justly claim, first 
 of all, our attention. 
 
 Many primitive peoples find a substitute for soap 
 in the roots, bark or fruit of certain plants. Nearly 
 every country is known to produce such vegetable 
 soaps, the quality which they possess of forming 
 an emulsion with oily substances being due to a 
 peculiar vegetable substance, known as Saponin. 
 Many of these saponaceous barks and fruits are 
 now used with good results — the "soap bark" 
 of the druggist being one of the best substances 
 for dressing over black dress goods, whether of 
 silk or woollen. 
 
 The fruit of the Soapberry tree — Papindus 
 Saponaria — a native of the West Indies, is said 
 to be capable of cleansing as much linen as sixty 
 times its weight of soap. 
 
 Wood ashes were probably used as cleansing 
 material long before soap was made, as well as 
 long after its general use. Their properties and 
 value will be considered later. 
 
58 
 
 THE CHEMISTRY OF 
 
 Soaps for laundry use are chiefly composed of 
 alkaline bases, combined with fatty acids. Their 
 action is "gently but efficiently to dispose the 
 greasy dirt of the clothes and oily exudations of 
 the skin to miscibility with, and solubility in wash 
 water." * 
 
 We may state it in this way. All kinds of 
 cleansing, whether it be of our skins, our clothes, 
 our painted wood-work, our windows or our dishes, 
 consist of two distinct operations : first, the solu- 
 tion or emulsion of the oily matter which causes 
 the dust and dirt to adhere ; second, the mechan- 
 ical removal of the dust and dirt, which, in most 
 cases, is effected by water. Sometimes, as in the 
 case of silver and paint, the cleansing agent is 
 fine sand or chalk. 
 
 It will readily be seen that the first operation — 
 the removal of the oily matter — is of prime im- 
 portance in the laundry. In order clearly to 
 understand the question of the best means to 
 secure this removal, we must first consider the 
 
 * Chemistry applied to the Manufacture of Soaps and Candles. 
 Morfit. 
 
COOKING AND CLEANING. 
 
 59 
 
 properties of the grease and oily matters, and next, 
 what agents will dissolve them or form an emulsion 
 with them. 
 
 Oily matters in general are soluble in certain 
 substances, as salt is soluble in water, and can be 
 recovered in their original form from such solutions 
 by simple evaporation. Some of them readily 
 combine with alkalies to form the kind of com- 
 pound which we call soap. Others in contact with 
 the alkalies form emulsions, so-called, in which the 
 fatty globules are suspended, forming an opaque 
 liquid. These emulsions are capable of being in- 
 definitely diluted with clear water, and by this means 
 the fatty globules are all carried away. The opacity 
 of soap-suds is due to the fact that it contains 
 particles in suspension, the nature of which will be 
 presently shown. 
 
 Setting aside the vegetable saponin, we have 
 then two classes of agents which affect oily mat- 
 ters, — the one class by simple solution, as turpen- 
 tine, alcohol, ether, benzine, etc. ; the other class 
 by a direct union, or by the formation of an 
 emulsion. Agents of the latter class are substances 
 
60 
 
 THE CHEMISTRY OF 
 
 known in chemistry as the alkali metals, and in 
 order to justify the somewhat extended discussion 
 of these alkali metals, we must remind our readers 
 that the value of all soaps as detergents depends 
 upon the alkali chiefly. To the distinguished 
 French chemist, Chevreul, is due our knowledge 
 of the action of soaps. 
 
 "The neutral salts formed by the alkalies and the 
 fat acids are decomposed by the water, whereby 
 insoluble double fat acid salts, — stearates, palmi- 
 tates, oleates — are separated, while the alkali is 
 set free. By means of the free alkali the im- 
 purities clinging to the materials are removed." 
 
 Every woman must have noticed the peculiar 
 opaque appearance of soap-suds, even before any- 
 thing has been washed in it. This is due to the 
 suspension in the water of the particles of these 
 "insoluble double fat acid salts." 
 
 [Hot water will dissolve soaps without this de- 
 composition, but on cooling the separation takes 
 place.] 
 
 As each soap-maker claims that his product 
 contains something which renders it better than 
 
COOKING AND CLEANING. 61 
 
 other soaps, or different from them, and as the 
 chief stress in his recommendation rests on the 
 fatty matters used, " Oil soap is superior to resin 
 soap," and the like, it behooves the housekeeper 
 to remember that, within certain limits of course, 
 the kind of fatty acid does not so much matter 
 to her (provided only that it is not putrid or 
 otherwise unfit for use) as the quantity and quality 
 of the alkali, and as she is often called upon to 
 believe that some new chemical has just been 
 discovered which makes a far more efficient soap 
 than the world has ever before seen, it may be 
 instructive for her to follow our discussions of the 
 alkali metals and their compounds. 
 
 The chemical group of " alkali metals " com- 
 prises six substances — Ammonium, Cassium, Lithium, 
 Potassium, Rubidium and Sodium. Two of the 
 six — Cassium and Rubidium — were discovered by 
 means of the spectroscope, not many years ago, in 
 the mineral waters of Durckheim, and probably 
 the total amount for sale of all the salts of these 
 metals, could be carried in one's pocket. A third 
 alkali metal — Lithium — occurs in several minerals, 
 
62 
 
 THE CHEMISTRY OF 
 
 and its salts are of frequent use in the laboratory, 
 but it is not sufficiently abundant to be of com- 
 mercial importance. 
 
 As regards the three remaining alkali metals, the 
 i i ii 
 
 oxide of Ammonium, (NH 4 )HO, is known as "Vola- 
 
 i I ii 
 
 tile Alkali," the oxides of Potassium, KHO, and 
 i i ii 
 
 Sodium, NaHO, as " Caustic Alkalies." With these 
 three alkalies and their compounds, and these alone, 
 are we concerned in housekeeping. The volatile 
 alkali, Ammonia, has been recently prepared in quan- 
 tity and price such that every housekeeper may 
 become acquainted with its use. It does not often 
 occur in soaps, and its use is confined to the more 
 delicate cleansing operations, the bath, the washing 
 of woollens, and other cases where its property of 
 evaporating, without leaving any residue to attack the 
 fabric or to attract anything from the air, is invaluable. 
 This property affords a safeguard against the care- 
 lessness of the laundress in not sufficiently rinsing 
 the fabric, and this imperfect rinsing is at the bottom 
 of most of the trouble in washing woollens with 
 soap or caustic alkali. All flannels worn next the 
 
COOKING AND CLEANING. 63 
 
 skin, all the woollens of an infant's wardrobe, should 
 be washed in water made soft and alkaline by 
 ammonia, or ammonium carbonate. An additional 
 advantage will be found in the fact that the shrink- 
 age of woollens thus washed is very slight. The 
 ammonium compounds are somewhat more ex- 
 pensive than the caustic alkalies, but in the present 
 time, when an ammoniacal liquor is largely produced 
 as a secondary product in the manufacture of coal 
 gas, the cost is not excessive compared with the 
 benefit its use confers. For use in the bath, and 
 for woollens, the ammoniacal gas liquor must have 
 passed through a process of purification, in order 
 to free it from some other products of the de- 
 structive distillation of coal, which is not healthful 
 or useful. This caution must be borne in mind, 
 as a crude article is sometimes sold for cleaning 
 paint or carpets ; this is not fit for the uses we 
 have been specifying. 
 
 Ammonia water, bought of the best dealers in 
 chemicals and druggists' supplies, costs about 30 
 cents a pint, without the bottle. 
 
 A pint of this liquid possesses as much alkaline 
 
64 
 
 THE CHEMISTRY OF 
 
 I IV II I II 
 
 value as ten ounces of sal soda, Na 2 C0 3 + ioH 2 0, 
 and has not the injurious properties of the latter, 
 even when used in excess. As the alkali is volatile, 
 and water nearly boiling will retain only about one- 
 seventh as much of the ammonia gas as water at 
 the ordinary temperature of the air, it will be seen 
 that the directions on the various bottles of 
 " Magical " washing fluids which contain ammonia, 
 to pour the required quantity into hot water, with 
 the word "hot" especially emphasized, are at 
 variance with the known properties of this sub- 
 stance. The fluid should be largely diluted with 
 cold water, and then added to the warm water, 
 never to water too hot to bear the hand in. 
 
 Ammonia is most excellent for cleaning glass 
 (but not for brass, as it dissolves copper, and 
 copper salts) . 
 
 A teaspoonful of ammonia, added to a quart 
 of water, is the best possible agent for cleansing 
 hair brushes. 
 
 For use in travelling, the solid ammonium car- 
 bonate is preferable ; for use in hard water it is 
 
COOKING AND CLEANING. 65 
 
 also better, as the lime is precipitated out by it as 
 by sal soda. It costs twenty-five or thirty cents 
 a pound, and one pound of it is of as much 
 alkaline value as two pounds of sal soda. 
 
 The compounds of the two alkali metals, Potas- 
 sium and Sodium, are capable of saponifying fats 
 and forming the complex substances known as 
 soaps. 
 
 For the compounds of these alkalies, employed 
 in the manufacture of soap, we shall use the 
 popular terms " potash " and "soda," as less likely 
 to cause confusion in our readers' minds. Potash 
 makes soft soap ; soda makes hard soap. Potash 
 is derived from wood ashes, and in the days of 
 our grandmothers soft soap was the universal 
 detergent. Potash (often called Pearlash) was 
 cheap and abundant. The wood fires of every 
 household furnished a waste product ready for its 
 extraction. Soda ash was, at that time, obtained 
 from the ashes of sea-weed, and of course was 
 not common inland. Aerated Pearlash (Potassium 
 bicarbonate), under the name of saleratus, was used 
 for bread. 
 
66 
 
 THE CHE MIS TR T OF 
 
 The discovery by the French manufacturer, 
 Leblanc, of a process of making soda ash from 
 the cheap and abundant sodium chloride, or com- 
 mon salt, has quite reversed the conditions of the 
 use of the two alkalies. Potash is now some 
 eight cents a pound, soda ash is only three. 
 
 In 1824, Mr. James Muspratt, of Liverpool, first 
 carried out the Leblanc process on a large scale, 
 and he is said to have been compelled to give 
 away soda by the ton to the soap-boilers, before 
 he could convince them that it was better than 
 the ashes of kelp, which they were using on a 
 small scale. But the soap trade, as we now know 
 it, came into existence after the soap-makers real- 
 ized the value of the new process. Soda ash is 
 now the cheapest form of alkali, and housekeepers 
 will do well to remember this fact when they are 
 tempted to buy some new " ine," or "crystal." 
 
 In regard to the best form in which to use the 
 alkali for washing purposes, experience is the best 
 guide, — that is, experience reinforced by judgment; 
 for the number of soaps, and soap substitutes, in 
 the market is so great, and the names so little 
 
COOKING AND CLEANING. 67 
 
 indicative of their value, that only some general 
 information can be given. 
 
 In the purchase of soap, it is safest to choose 
 the make of some well-known and long-established 
 firm, of which there are several who have a repu- 
 tation to lose if their product is not good ; and, 
 for an additional agent, stronger than soap, it is 
 better to buy sal soda (sodium carbonate) and 
 use it knowingly, than to trust to the highly lauded 
 packages of the grocery. A pound of sal soda 
 contains from four to five times as much alkali as 
 a pound of hard soap, and therefore it should 
 be used with care. 
 
 Washing soda should never be used in the solid 
 form, but should be dissolved in a separate vessel, 
 and the solution used with judgment. The inju- 
 dicious use of the solid is probably the cause of 
 the disfavor with which it is so often regarded. 
 One of the most highly recommended of the scores 
 of " washing compounds" in the market, doubtless 
 owes its popularity to the following directions : 
 "Put the contents of the box into one quart of 
 boiling water, stir well, then add three quarts of 
 
G8 
 
 THE CHEMISTRY OF 
 
 cold water : this will make one gallon. For washing 
 clothes, allow two cupfuls of liquid to a large tub 
 of water." 
 
 As the package contains about a pound of 
 washing soda, this rule, which good housekeepers 
 have found so safe, means about two ounces to a 
 large tubful of water, and this in solution. 
 
 Ten pounds of washing soda can be purchased 
 of the grocer for the price of this one-pound 
 package, with its high-sounding name. Nearly all 
 the compounds in the market depend upon washing 
 soda for their efficiency. Usually they contain 
 nothing else. Sometimes soap is present and, 
 rarely, borax. In one or two, ammonia has been 
 found. 
 
 For hard water, a little sal soda is almost indis- 
 pensable. Borax is a very good cleansing agent 
 for many purposes. The sodium is in a milder 
 form than in washing soda. For delicate fabrics 
 and for many colored articles, it is the safest 
 substance to use. 
 
 On first thought, we may wonder why we need 
 to add these chemical agents to soap, when our 
 
COOKING AND CLEANING. 69 
 
 grandmothers did without them ; but we must 
 remember that our grandmothers used soft soap 
 and wood ashes for all the cleansing operations 
 for which we now depend upon hard soap. It is 
 a recognized fact that soft soap is much more 
 caustic and hence more effective in removing 
 grease than hard soap. The reason for this lies 
 partly in the fact that the gelatinous character of 
 the soap allows a considerable proportion of free 
 lye to be mechanically held in the mass, and partly 
 because potash is a more powerful chemical agent 
 than soda. 
 
 Many prudent housewives still make soft soap 
 for their own use. Many more add to the effi- 
 ciency of the common soap by dissolving several 
 pounds of it in hot water, adding about one-third 
 as many pounds of sal soda, and allowing the 
 mass to cool into a white, soft curd. 
 
 A washing fluid, said to be of great value, is 
 prepared by the addition of freshly slaked lime to 
 a solution of sal soda. When the liquid has 
 become clear, alcohol is added to it, and it is 
 bottled for use. 
 
70 THE CHEMISTRY OF 
 
 II I II 
 
 Slaked lime, CaH 2 2 , or caustic lime, and car- 
 i ii 
 
 bonate of soda, Na 2 (CO s ), put together in solution, 
 
 ii ii 
 
 must inevitably result in carbonate of lime, Ca(C0 3 ), 
 I I ii 
 
 and caustic soda, 2NaHO, — a compound much 
 more dangerous to use in excess than sal soda. 
 The alcohol dilutes this caustic solution, and the 
 little gill cup used to measure the fluid for use, 
 insures safety. The mistress who considers herself 
 cautious will sanction the use of this "fluid," when 
 she will not allow sal soda to be used. 
 
 Turpentine has been sometimes recommended as 
 an addition to washing fluids, but its use may be 
 attended with danger, as, when applied in hot 
 water, to the bare arms of the laundress, it is 
 readily absorbed, and is liable to cause illness. 
 
 There is a compound of sodium of great value 
 for laundry and common use, which seems to take 
 the place of the old-time soft soap. This is sodium 
 silicate, water-glass, or soluble glass. It is manu- 
 factured for print works, and its common name is 
 "water-glass," that is, glass soluble in water, and 
 free from the lime or lead of the common window- 
 
COOKING AND CLEANING. 
 
 71 
 
 glass. Being made from clean materials, sand and 
 soda, or potash, it has no reminder of the dead 
 meat or bone-boiler's establishment, as soap some- 
 times has. The affinity of the alkali for the silica 
 is not strong, and yet it holds until some stronger 
 acid comes in contact with it. By virtue of this 
 property, it is said by the few housekeepers who 
 have hitherto had access to it, not to injure the 
 fabric, even if used in excess, and to give to 
 linen the clean, fresh appearance of new cloth. 
 It is hoped that an agent so valuable to the 
 housekeeper may soon be accessible to all. 
 
 The removal of spots from clothing is a subject 
 which has perplexed every woman. 
 
 The fabrics upon which we wish to operate are 
 nearly all colored, and the modern dye is such a 
 complex and unstable compound that disaster is 
 not uncommon. 
 
 Chloroform, ether, alconol, benzine, turpentine, 
 all dissolve gre-ase, but all are liable to show an 
 enlarged ring if not very carefully applied, and the 
 water in ether and alcohol affects many colors. 
 Turpentine is useful for some coarser fabrics, but 
 
72 
 
 THE CHEMISTRY OF 
 
 for the most delicate silks and woollens benzine 
 or naphtha is the safest, not injuring the color, and, 
 if pure, completely volatile. 
 
 For grease on carpets or other articles, where 
 washing is out of the question, absorbents may 
 be used : such as powdered soapstone, magnesia, 
 buckwheat flour, etc. 
 
 These absorbents are also sometimes used to 
 remove spots other than those caused by grease. 
 
 Grass stains often baffle the best laundress. A 
 sure, if expensive, solvent for chlorophyl (the green 
 coloring matter of plants) is alcohol, if applied 
 while the stain is still fresh. Fruit stains are generally 
 removed by the well-known process of pouring 
 on boiling water. In some cases oxalic acid is 
 better. 
 
 Red iron rust is most readily soluble in muriatic 
 acid, and if one has a little knowledge of chemical 
 principles, this acid may be of great use in the 
 laundry. It is very readily washed out with clear 
 water, and it does not affect most fast colors. As 
 the iron compound formed is also soluble, it can 
 be taken away entirely. The efficacy of salt with 
 
COOKING AND CLEANING. 73 
 
 lemon is probably due to the setting free of a small 
 amount of muriatic acid. 
 
 Black iron stains, as those from the inks made 
 with iron, may be best removed by oxalic acid, 
 although it has little effect on red iron stains. 
 The iron forms a colorless compound with the acid 
 but great care must be taken to remove all of it by 
 a thorough washing. The difficult solubility of oxalic 
 compounds makes this harder. It is well to 
 wash the article with ammonia water finally, in 
 order to remove the last traces of acid. Oxalic 
 acid and ammonia are two of the most useful 
 agents in the laundry. For further details, see 
 chapter II. 
 
 It may comfort some young housewife to know 
 that mildew is beyond the art of the chemist. It 
 seems to be a vegetable growth, which attacks 
 the cotton fibre, and in a measure destroys it, as 
 dry rot does a stick of timber. If it is superficial 
 only, successive washings and bleachings in the 
 sun will remove it. If deep seated, its removal is 
 hopeless ; as in other cases, prevention is the best 
 cure. Some cloth is very liable to mildew, and 
 
74 
 
 THE CHEMISTRT OF 
 
 servants are often blamed for its appearance without 
 good cause. 
 
 We will now consider some of the preparations 
 for the mechanical removal of " matter in the wrong 
 place" — tarnish on silver, spots on paint, etc. 
 
 The matron of fifty years since, took care of her 
 silver herself, or superintended the cleaning very 
 closely, for the heirlooms were precious, or the 
 gifts of friends valuable. The silver was hardened 
 by a certain proportion of copper, and took a polish 
 of great brilliancy and permanence. The matron 
 of to-day, who has the same kind of silver, and 
 who takes the same care, is the exception. Plated 
 ware is found in nearly every household in our 
 villages. The silver deposited from the battery 
 is only a thin coating, and is of pure, soft metal — 
 very bright when new, but easily scratched, easily 
 tarnished, and never again capable of taking a beautiful 
 polish. The utensils, being of comparatively little 
 value, are left to the table-girl to clean, and of course 
 she uses the material which will save her labor. 
 
 In order to ascertain if there was any foundation 
 for the prevalent opinion that there was mercury 
 
COOKING AND CLEANING. 75 
 
 or some equally dangerous chemical in the silver 
 powders commonly sold, we have purchased sam- 
 ples in Boston and vicinity, and in New York and 
 vicinity. 
 
 Thirty-eight different kinds have been found. 
 Of these, 
 
 25 were dry powder. 
 10 " partly liquid. 
 3 " soaps. 
 
 Of the twenty-five powders, fifteen were chalk 
 or precipitated calcium carbonate, with a little 
 coloring matter, usually rouge. 
 
 6 were diatomaceous earth. 
 2 " fine sand entirely. 
 2 " u " partly. 
 
 Mercury was found in none. No other injurious 
 chemical was found in any save the "electro-plating 
 battery in a bottle," which contained potassium 
 cyanide, KCy, a deadly poison ; but it was labelled 
 poison, although the label also stated that all salts 
 of silver are poison when taken internally. This 
 preparation does contain silver, and does deposit a 
 thin coating, but it is not a safe article. 
 
76 
 
 THE CHEMISTRY OF 
 
 Of the nine polishes, partly liquid, five contained 
 alcohol and ammonia for the liquid portion ; four, 
 alcohol and sassafras extract. The solid portion, 
 in all cases, was chalk, with, in one case, the 
 addition of a little jeweller's rouge. 
 
 The caution to be observed in the use of these 
 preparations is in regard to the fineness of the 
 material. A few coarse grains will scratch the 
 
 II IV II 
 
 coating of soft silver. Precipitated chalk, CaC0 3 , 
 
 IV II 
 
 or well-washed diatomaceous earth, Si0 2 , seem to 
 be of the most uniform fineness. 
 
 We may learn a lesson in this, as well as in 
 many other things, from the. old-fashioned house- 
 wife. She bought a pound of whiting for twelve 
 cents, floated off the fine portion, or sifted it 
 through fine cloth, and obtained twelve ounces of 
 the same material, for three ounces of which the 
 modern matron pays twenty-five or fifty cents, 
 according to the name on the box. 
 
 Silver is liable to tarnish from many causes, some 
 of which can be avoided. Flannel is apt to con- 
 tain sulphur, and should not be used to wrap up 
 
COOKING AND CLEANING. 77 
 
 silver articles. Clean, soft tissue paper first, then 
 a bag of Canton flannel, form a good covering. 
 Want of sufficient ventilation in a house shows 
 itself very quickly by the tarnish on the silver, 
 caused by foul air and coal gas. 
 
 Iron and steel oxidize in damp air, according 
 to the rule that the presence of water favors 
 chemical change. A little oily coating will exclude 
 the air and hence no oxidation can ensue. 
 
 The mechanical removal of spots on paint and 
 kitchen utensils is effected by scouring agents, 
 
 II IV II n IV II 
 
 such as chalk, CaC0 3 , whiting impure, CaCO s , 
 pumice and Bristol brick (silicates), fine sand 
 
 IV II 
 
 Si0 2 , and preparations which owe their cleansing 
 properties to one of these solids. 
 
 A frequent source of annoyance is the bluing, 
 which seems to be indispensable to the city laun- 
 dress, who has not fresh grass, or the white snow 
 of the country on which to whiten her clothes. 
 
 Three substances are at present used for this 
 purpose. Indigo, from the plant Indigo tinctoria, 
 has been known from time immemorial. Soluble 
 
'78 
 
 THE CHE MIS TR T OF 
 
 Prussian blue, a chemical compound containing 
 iron, is a recent invention. Ultramarine, the third, 
 is a silicate, insoluble in water, giving a tint by 
 means of the very fine blue powder, which is im- 
 pacted in the cloth. 
 
 The indigo bags of olden time have been almost 
 entirely replaced by numerous " Soluble Blues," 
 all of which are Prussian blue of greater or less 
 strength. 
 
 It must be borne in mind that this substance is 
 decomposed by the fixed alkalies, and if the clothes 
 are not rinsed free from soap-suds or washing 
 soda, mysterious iron-rust spots may appear on 
 the linen, caused by the decomposition of the 
 bluing. The general yellowish tint, which is so 
 often seen on linen, is probably due to this cause. 
 
 Of fifteen different kinds of bluing which were 
 examined, not one was anything but Prussian blue. 
 Here, as in so many other cases, the young house- 
 keeper who has had some training in a chemical 
 laboratory, has an advantage over one who has not, 
 in her idea of absolute cleanliness, and her con- 
 ception of the inexorable laws of chemical change. 
 
COOKING AND CLEANING. 
 
 79 
 
 A long chapter might be written on the subject 
 of economy in the case of the multitude of chemical 
 preparations so freely offered for sale. There is 
 so much for the young housewife to do that she 
 is tempted by every promise of making labor easier, 
 and is very ready to try anything that is 
 recommended. 
 
 She thinks that if her servants are provided with 
 all the modern appliances for doing work quickly 
 and well, it is their fault if they do not ac- 
 complish it. She forgets that the past generation 
 of women, who succeeded in keeping their families 
 healthy and happy, brought brains to the work ; 
 they knew, too, the properties of the substances 
 they used, because they prepared them at home. 
 
 When American girls will learn to apply Chem- 
 istry and Physics to every-day life, we may hope 
 for a speedy solution of the servant-girl ques- 
 tion. 
 
CHAPTER II. 
 
 CHEMICALS FOR HOUSEHOLD USE. 
 
 I. 
 
 Acids. 
 
 HERE are three acids which should be found 
 
 in every laundry cupboard : acetic acid, 
 
 IV I II II 
 
 C 2 H 4 2 ; muriatic or hydrochloric acid, H CI; and 
 
 oxalic acid, C 2 H.0 4 . 
 
 Vinegar can be used in many cases instead of 
 acetic acid ; but vinegar contains coloring matters 
 which stain delicate fabrics, and it is better to 
 use the purified acid, especially as the so-called 
 vinegar may contain sulphuric acid. 
 
 If soda has been spilled on black silk an ap- 
 plication of acetic acid will usually restore the 
 color. 
 
 IV 
 
 ii 
 
THE CHEMISTRY OF COOKING, ETC, 81 
 
 Many of the bright blue flannels and other 
 fabrics found at the present time in our markets 
 owe their brilliant shades to an acid compound of 
 a coal-tar color, and as soon as they are washed 
 in soap or ammonia, the alkali neutralizes the 
 acid, and the color becomes pale and faded in 
 appearance. If acetic acid or vinegar is added to 
 the second rinsing water, the bright color is in all 
 such cases restored. This fact was discovered by 
 accident, and is well worth remembering. Of 
 course, not all shades of blue are made with this 
 compound, and hence not all faded blues can be 
 thus restored. It is well to test a bit of the 
 cloth before washing the whole garment. 
 
 A weak acid like acetic acid is safe to use on 
 many fabrics which would be injured by a strong 
 acid. 
 
 Muriatic or hydrochloric acid is useful in a 
 multitude of ways. By means of it, the writer 
 once restored, in a few minutes, a delicate blue 
 cambric dress, which had been quite ruined by nu- 
 merous large stains of red iron rust. The cloth was 
 laid over a large bowl half filled with hot water, 
 
82 
 
 THE CHEMISTRY OF 
 
 and the spots thus steamed were touched with a 
 drop of the acid, and as soon as the iron was 
 dissolved, the cloth was plunged into the water to 
 prevent injury to the cotton fibres. All the spots 
 were thus dissolved off ; the garment was then 
 quickly rinsed in several waters, and finally in water 
 containing a little ammonia, which neutralized any 
 trace of acid still remaining. This process is by 
 far the best for removing red iron stains from 
 white cloth. 
 
 Porcelain or china, stained with iron, can be 
 cleaned with muriatic acid. For the porcelain or 
 enamelled water-closet basin it is especially useful, 
 but the acid must be removed by rinsing with 
 water followed by a little alkali to save the iron 
 pipes below. 
 
 The acid must not be used on marble, as it 
 dissolves it with great rapidity, and the polish is lost. 
 
 The property which muriatic acid, in common 
 with the so-called stronger acids, possesses — that of 
 liberating carbonic acid gas with brisk effervescence 
 from its compounds, renders this acid valuable for 
 the detection of carbonates. 
 
COOKING AND CLEANING. 83 
 
 For instance, if the label of a washing powder 
 claims it to be something new, and requires that 
 it be used without soda, as soda injures the clothes, 
 it can be tested as follows : Put half a teaspoonful 
 of the powder into a tumbler, add a little water, 
 then a few drops of muriatic acid. A brisk effer- 
 vescence will prove it to be a carbonate, and if 
 the edge of the tumbler is held near the colorless 
 flame of an alcohol lamp, the characteristic yellow 
 color of sodium will complete the proof. If the 
 acid is added drop by drop until no more effer- 
 vescence occurs, and there remains a greasy scum 
 on the surface of the liquid in the tumbler, the 
 compound contains soap as well as sal soda, for 
 the acid unites with the alkali of the soap and 
 sets free the grease. 
 
 If some very costly silver polishing powder is 
 offered as superior to all other powders, a drop 
 or two of muriatic acid will decide whether or not 
 
 II IV II 
 
 it is chalk or whiting (CaC0 3 ) by the efferves- 
 cence or liberation of the carbonic acid gas. 
 
 Oxalic acid is purchased in white crystals, 
 and for use a saturated solution is made ; as one 
 
S4 
 
 THE C HEM IS TR T OF 
 
 part of it dissolves only in several parts of water, it 
 is well to keep an excess of the crystals in the bottle. 
 It is somewhat poisonous, and should not be left 
 in the solid form within reach of careless people. 
 A small bottle of liguid can, however, be kept 
 with other laundry articles. 
 
 This acid is the only efficient means which is 
 known to the writer, for removing the shoe- 
 leather stains from white stockings. It will take 
 out most fruit stains on napkins and from the 
 fingers ; for the latter purpose tartaric acid will 
 also serve. 
 
 Oxalic acid is invaluable to the housekeeper 
 as a means of removing black iron stains, such as 
 those caused by the iron inks. 
 
 It is a more powerful acid than acetic acid, 
 and must be carefully removed from cloth by 
 rinsing with water and finally by ammonia. 
 
 Oxalic acid is very efficient as an agent for 
 cleaning brass, and seems even safer to use than 
 acetic, as the compound of the latter with copper 
 salts is one of the most dangerous of the copper 
 compounds. 
 
COOKING AND CLEANING. 
 
 85 
 
 TV II 
 
 Sulphurous acid gas (S0 2 ) is obtained by burn- 
 ing sulphur, and is the well-known agent for 
 bleaching. It will often remove spots which noth- 
 ing else will touch. The cloth or other substance 
 should be moistened and held over a bit of burning 
 julphur ; as the agent is an acid, the same pre- 
 cautions must be observed as in the case of the 
 other acids, as to the removal of the corrosive 
 substance. 
 
 2. Alkalies. 
 
 The uses of ammonia water and ammonium carbon- 
 ate, have been considered in the text ; a precaution 
 to be taken is, that the bottles should not be kept 
 with other bottles containing liquids for internal use, 
 as distressing accidents have occurred from swallow- 
 ing ammonia. 
 
 Caustic soda or potash is better for greasy tins 
 than soap ; a swab should be used to apply it, 
 however, as it is corrosive to the hands. Silicate 
 of soda may also be used for this purpose. 
 
 Some alkali should be always at hand. The 
 alkali compounds, sodium carbonate (sal soda) 
 
86 
 
 THE CHEMISTRY OF 
 
 I V II I II II IV II 
 
 Na 2 C0 3 + H IO H 2 and calcium carbonate CaC0 3 , 
 
 are of daily use as has been already explained in 
 the previous chapter. 
 
 BOOKS FOR REFERENCE. 
 
 For Teachers: 
 
 " History of Chemical Theory." 
 
 A. Wurtz. 
 
 Translated and edited by Henry Watts. 
 " Elementary Manual of Chemistry." 
 
 Eliot and Storer. 
 
 "Physiology and Hygiene." (Chapter on Digestion.) 
 
 Huxley and 7"oumans. 
 
 "Treatise on Chemistry." 
 
 Roscoe and Schorlemmer. 
 
 For General Readers : 
 " Elements of Chemistry." 
 
 Le Roy C. Cooley. 
 
COOKING AND CLEANING. 87 
 
 "The Birth of Chemistry." 
 
 Rod-well. 
 
 "Chemistry of Common Life." 
 
 Johnston and Church {?ieiv edition). 
 
 "The New Chemistry." 
 
 J. P. Cooke. 
 
 "Lessons on Elementary Chemistry." 
 
 Henry E. Roscoe. 
 
 " Fermentation." 
 
 Schntzenberger. 
 
 " Vortrage uber die Entwickelungsgeschichte der Chemie 
 in den letzten Hundert Jahren." 
 
 Dr. A. Ladenburg . 
 
 Table of some common elements with their atomic 
 weights and symbols. 
 
 NAME. 
 
 SYMBOL. 
 
 ATOMIC WEIGHT. 
 
 Hydrogen 
 
 H 
 I 
 
 CI 
 
 I. 
 
 Chlorine 
 
 35*5 
 
 Sodium 
 
 I 
 
 .Na 
 
 23- 
 
 Potassium 
 
 I 
 
 K 
 I 
 
 Ag 
 
 II 
 
 O 
 
 II 
 Cu 
 
 39.1 
 
 Silver 
 
 Oxygen 
 
 Copper 
 
 108. 
 16. 
 63-4 
 
THE CHE MIS TR T OF COOKING, ETC. 
 
 NAME. 
 
 Calcium 
 
 Barium 
 
 Lead 
 
 Zinc 
 
 Boron 
 
 Gold 
 
 Iron 
 
 Aluminum 
 
 Tin 
 
 Silicon 
 
 Carbon 
 
 Nitrogen 
 
 Arsenic 
 
 SYMBOL. 
 
 ATOMIC WE 
 
 II 
 
 
 Ca 
 
 40. 
 
 II 
 
 
 Ba 
 
 i37- 
 
 II 
 
 
 Pb 
 
 207. 
 
 II 
 
 
 Zn 
 
 65.2 
 
 III 
 
 
 B 
 
 1 r. 
 
 III 
 
 
 Au 
 
 197. 
 
 II IV 
 
 
 Fe or Fe 
 
 56. 
 
 II IV 
 
 
 Al or Al 
 
 27.4 
 
 II IV 
 
 
 Sn or Sn 
 
 11S. 
 
 IV 
 
 
 Si 
 
 28. 
 
 IV 
 
 
 C 
 
 12. 
 
 III V 
 
 
 N or N 
 
 14. 
 
 III V 
 
 
 As or As 
 
 75- 
 
INDEX. 
 
 Page. 
 
 Absorption of Food, ... 44 
 
 Acetic Acid, 80 
 
 Acids : 
 
 Acetic, • . . • • .• .• 80 
 Hydro-chloric or Muriatic, 80 
 
 Oxalic, 73-80 
 
 ^ Tartaric, 49 
 
 Acid Phosphate, 49 
 
 Albumen, 38 
 
 Albuminous Food, .... 41 
 
 Alcohol, 29-59-71 
 
 Alkalies, 85 
 
 Caustic, 62 
 
 Volatile, 62 
 
 Alum, 33-49 
 
 Ammonia, 61-63-64-85 
 
 Ammonium Carbonate, . 63-64-85 
 
 Assimilation, 44 
 
 Atomic Weight, 5 
 
 Baking Powders, 32*49 
 
 Benzine, 59-7* 
 
 Bluing, 77 
 
 Books for Reference, ... 86 
 
 Borax 68 
 
 Bread, 24 
 
 Fermented, 28 
 
 Reason for Kneading, . 28 
 Temperature for Ferment- 
 ing 28 
 
 Temperature for Baking, 29 
 
 Snow- Bread, 30 
 
 Soda-Bread, .... 31-32-33 
 Carbonic Acid, Gas, . . . 27-31-49 
 
 Cassium; 61 
 
 Chemical Change, .... 1-16 
 
 Element, 3 
 
 Equation, 11 
 
 Reaction, ...... 11 
 
 Chloroform, ji 
 
 Pagk. 
 
 Cleaning : 
 
 Brass, 84 
 
 Brushes, 64 
 
 Glass, 64 
 
 Paint, . 64 
 
 Silver, 74*75 
 
 Cooking;, 45 
 
 Of Starch, 23 
 
 Of Nitrogenous Food, . 39 
 Cost of Nitrogenous and Vege- 
 table Diet in Germany 
 
 compared, . . : . . 48 
 
 Cream of Tartar, 32-49 
 
 Danger : 
 
 Acetic Acid on Copper, . 84 
 
 Ammonia, 85 
 
 " Battery in a Bottle," . 75 
 
 Hardwater, 40 
 
 Soda, 39 
 
 Turpentine in Washing, . 70 
 
 Diastase, 20 
 
 Ether, 59-71 
 
 Fats 34-35 
 
 Decomposition of . . . 47 
 
 Fruit Stains, 72 
 
 Glucose, 21 
 
 Gluten, 27 
 
 Grass Stains, 72 
 
 Grease on Carpets, .... 72 
 Growth Nitrogenous Food re- 
 quired for, 37 
 
 Heat— Artificial, ..... 16 
 
 Source of in Animals, . 17 
 
 Heat-producing Food, ... 18 
 
 Ink Stains, 73 
 
 Iron, Black Stains of . . 73-82-84 
 Rust, ...... 72-78-81 
 
 Law of Definite Proportion by 
 
 Weight, i» 
 
90 
 
 INDEX. 
 
 Page. 
 
 Lime, - 
 
 Lithium, 61 
 
 Magical Washing Fluids, . . 64 
 
 Mildew, 7 , 
 
 Milk \\ 
 
 MuiUticAcid 8i 
 
 Nitrogen, 37 
 
 Percentage of in Food, . 50-53 
 Required in Growth and 
 
 Work, , 7 
 
 Oils, 34.35 
 
 Oxalic Acid, 83 
 
 Pearl Ash, 65 
 
 Plate Powders, 75 
 
 Potash, 65-85 
 
 Potassium, 61 
 
 Potassium Cyanide, .... 75 
 Princ pies of I >iet, .... 40 
 Properties of Substances, . . 1 
 Proportion of Nitrogenous 
 
 Food required, ... 46 
 Ptyalin in Saliva, .... 22 
 Relation of Climate to Food, 40 
 Removal of Spots, . . . 71-72-85 
 Residues from Baking Pow- 
 ders, 32-33 
 
 Restoring Color, 80-81 
 
 Roche lie Salts, 49 
 
 Rubidium, 61 
 
 Rust of Iron, 72-81 
 
 Sal Soda, 65-67-85 
 
 Salt, 32-47 
 
 Saponin, 57 
 
 Silver-Tarnish, 74 
 
 Snow-Bread 30 
 
 Soa P'- , 55-58 
 
 Bark, , 57 
 
 Berry Tree, 57 
 
 Soda, . ....... 33-49-85 
 
 Soda Ash, 66 
 
 Soda Bread, 31-32-33 
 
 Sodium, 61 
 
 Carbonate, 67 
 
 Silicate, 70 
 
 Soft Soap, ....... 69 
 
 Page. 
 
 Soluble Glass, 70 
 
 Stains, 71-72-80-82-84 
 
 Starch, . ,8 
 
 Chemical Changes of . . 20 
 
 Cooking of 23 
 
 Sugar 20 
 
 Tables: 
 
 I. Atomic Weights, . 5 
 II. Exchangeable Val- 
 ues, 7 
 
 III. Interchangeable 
 
 Values, ... 9 
 
 IV. Mineral Acids, . . 14 
 Baking Powders ... 49 
 Composition of Some Ani- 
 mal Food, 50-54 
 
 Composiiion of Some 
 
 Vegettble Food, . . 51-54 
 Comparative Digestibility 
 
 of Food, 52 
 
 Daily Weight of Food 
 
 Required, 53 
 
 Percentages of Waste, . 54 
 
 Tannin, 47 
 
 Temperature for Fermenting 
 
 Bread, 28 
 
 For Baking Bread, . . 29 
 
 Tests with Muriatic Acid, . 83 
 
 Tobacco, 47 
 
 Turpentine 59-70-71 
 
 Transfer of Force- Producing 
 
 Power, 42 
 
 Unit of Value, 6-7 
 
 Vinegar, 80 
 
 Volatile Alkali, 62 
 
 Yeast, 27 
 
 Yellow Tint on Linen, ... 78 
 
 Washing Fluids, 69-70 
 
 Washing Woollens, .... 62-63 
 Water as the Heat- Regulator 
 
 of the Body, .... 46 
 
 Water Glass, 70 
 
 Wood Ashes, 57-59 
 
 Work, Nitrogenous Food Re- 
 quired for 37 
 
'7 f> 
 
 S : \ 
 
 GETTY RESEARCH INSTITUTE 
 
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