The chemistry of cooking and cleaning

Preface

IN 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.

There is a space yet unoccupied for an elementary work which shall give to non-scientific readers some practical information as to the chemical composition 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 most persons have a dim idea of what some part of it means. To gather up these indistinct notions into a definite and practical form is the aim of this little book.

iv PREFACE.

There is, lingering in the air, a great awe of chemistry 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 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, so far as they apply to 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.

PREFACE

To the Second Edition.

THE science of chemistry has made rapid strides in the past fifteen years. Biological science has sprung from infancy to sturdy manhood during the same time, and a knowledge of both with their relations to each other is necessary to the right understanding of the manifold operations of life. All the sciences and all the arts are taxed by thq intelligent home-maker for the proper foundation and continuance of the complex life of the home.

The establishment of more homes and their right conduct when established, which results in the better utilization of time, money and strength, means the perpetuity, prosperity and power of the nation.

Without trespassing upon the domain of household bacteriology, a knowledge of the chemistry of cooking and cleaning must include some discussion of the sources of dirt, its composition and its dangers, and the discussion of methods for its removal, which shall at the same time be speedy, safe and effectual.

vi PREFACE.

Experience teaches that in domestic work there is no best rule of universal application. Circumstances vary so widely that principles, alone, can be laid down. Each case requires a large proportion of judgment — a compound of more complex composition than any chemical substance ever dealt with.

If any housekeeper finds a method better for her purpose than the one specified here, let her keep to its use and tell it to others. This work will have accomplished its purpose if it interests those who understand already the principles of cooking and cleaning; gives a few answers to those who continually ask "Why?" and "How?" and stimulates to study and thought the many who have long labored with willing hearts but with untrained minds and hands.

Boston, 1897.

I. Dust 71

II. Dust Mixtures (Grease and Dust) . . 87

III. Stains, Spots, Tarnish 100

IV. Laundry 118

V. Chemicals for Household Use .... 145

Books of Reference 153

Index 155

THE CHEMISTRY OF COOKING AND CLEANING.

CHAPTER I. Matter and Its Composition

WE give the name matter to the objects which can be recognized by any one of our senses. There are many kinds of matter and many forms of one kind. Ice melts into water, water changes into steam. In our stoves, the hard, black coal disappears, leaving a soft, gray ash, that weighs much less than the original coal. Something has been taken away.

The leaf is covered by wind-blown soil and soon no leaf is there; but the matter of which it was composed is still somewhere, for that is never lost. Living matter is in constant change from one form to another. Our bodies are composed of matter, and to their continued existence, as well as to their growth, material substances are necessary. Some changes come quickly, some slowly. Years, ages even, are sometimes necessary to bring a result that is visible to us.

Matter.

A familiar substance, sugar, for example, may be subjected to different changes. Put two tablespoonfuls of white sugar into a scant half cup of water. The sugar disappears. The clear water changes to a syrupy liquid. If the water is allowed to evaporate slowly, the sugar is found to remain.

A teaspoonful of sugar dropped upon the warm stove changes in character. There appears a black mass, which is readily recognized as charcoal.

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 substance dissolved in water. The new substance has the properties of neither of the others. The acid and the alkali have lost their identity.

Dissolve a teaspoonful of sugar in a cupful of water. Add a very little yeast and put the cup in a warm place. Soon bubbles of gas rise and break on the surface; while, on distilling the liquid, a new acquaintance presents itself in the form of alcohol. The first-mentioned change in the sugar is a physical change — the character of the substance is not permanently altered. The second is a chemical change — the substance loses its individual character. The third change in the sugar, most important for our present purpose, combines chemical and physical changes caused by the action of life. When the syrup "sours" or ferments, we know that living organisms are at work in the solution, changing the substance by their own processes of growth. To this class, then, we may apply the name biological change. Here belong the changes in our own bodies which enable them to live and grow. Death comes when these "vital" changes can no longer proceed in a normal, healthy manner.

Changes in matter, then, are of two kinds.

I. Physical. Change of form, without change of character. This is brought about by outside forces: heat, blows, etc.

II. Chemical. Change of character, with or without change of form. This is brought about by chemical agencies, by fire and electricity — also forces from without.

Physical and chemical forces, working together, allow of biological results, caused by living cells producing energy or force by means of their life processes.

Under these heads come the numerous changes which every housewife observes and which all should understand, so far as such understanding is necessary for the true economy of the house.

We have seen that matter is subject to two kinds X?™* of

•> JVl atter.

of change. Experience teaches that matter exists in three different forms — solids, liquids and gases.

It teaches, also, that by the action of outside forces some solids become liquids and some liquids become gases. The reverse process, also, is known — gases change into liquids and liquids into solids. The chemist or physicist is able to change matter from one form into another in many more instances than are observed in ordinary experience. h r a°n|e C in USmg What force, or forces, cause or can be made to tatter. cause these changes? Before an iron kettle or

stove can be made, the metal from which it is formed must be subjected to intense heat, when it will become a liquid and can be poured into molds of any desired shape. The solid ice melts or becomes water at a low temperature; but at a higher degree of temperature, the water becomes steam or gas. Some solids, as camphor and iodine sublime, that is, pass directly into the gaseous form.

Heat, then, is one force which brings about a change of state in material substances. If heat be abstracted from a liquid, the latter may become a solid, as when water becomes ice. Like changes are less readily brought about by pressure, gases becoming liquids; liquids becoming solids. Cold and pressure, acting together, are able to liquefy the air even, and other gases once called permanent.

The forces exerted from without, then, are pressure, and the addition or subtraction of heat.

COOKING AND CLEANING.

Experience teaches that solid and liquid matter may be divided into smaller and smaller divisions until the particles are no longer visible under a powerful microscope. The scientist is led by his observations to the belief that matter is made up of infinitesimal particles or atoms and that chemical changes take place among these atoms and groups of atoms. They are invisible and indestructible. Each atom occupies space and has weight. Two or more atoms united make a molecule, which also is very far from being visible. It may be composed of two or more atoms of the same substance or many atoms of different substances.

In the social world there are individuals, families and communities; so in the material world there are atoms, simple molecules and complex groups of molecules. The groups or molecules are always separated from each other by greater or less distances. If the groups are many and the distances between them infinitely small, there is a "solid crowd." There must be some force to widen the distance between the groups and make them free to move among themselves. A layer of fat is a crowded mass of molecules — a solid. Heat drives the molecules apart, increases the distance between them, gives them a chance to move more freely and produces, thus, the liquid condi-

Atoms and Molecules.

States of Matter.

tion. Still further separation, with the breaking up of certain groups causes a freedom of movement in any and all directions, giving a gas or gases. If not restrained, these may pass entirely beyond our ken though still existent, for "matter cannot be created or destroyed at will."

Different degrees of heat produce varying degrees of liquefaction. The molecules may be given only a slight freedom of movement, causing a semi-liquid state, as in the melting of solder, of gelatine, and of tar. When the molecules are driven further apart the mass necessarily occupies more space. This is expansion. All matter expands or occupies more space under the action of heat; but in gases, the proportion of expansion is much the greatest, for the molecules have perfect freedom of movement. This expansion of gases with heat makes possible the process of ventilation by means of an open fire, and is one factor in the rise of dough.

Into these molecular spaces, molecules of other substances may enter. The molecules of solids, however, do not readily pass between one another in this way. The solids must be changed to liquids, that their molecules may have freedom of movement. This is commonly brought about by solution.

The degree of solubility of any substance depends largely upon the temperature of the solvent. Common salt dissolves nearly as well in cold as in warm water. "Soda" and alum dissolve more readily in warm than in cold, while cream of tartar requires hot water for its complete solution.

The amount of solid which water will dissolve saturation, usually increases with the temperature to a certain degree. After this no more will dissolve and the solution is "saturated." Gases readily dissolve in water, but, usually, in cold solutions only.

The action of the liquid is increased if the solid be first powdered, for a greater area is thus presented to the action of the liquid. It is usually more rapid when the powder is placed upon the surface. Under these conditions each particle, while dissolving is surrounded by a thin envelop of syrup, which becomes heavier and sweeter. The film of syrup is washed away by the solvent liquid, so that a clean surface is continually exposed to be acted upon. Some particles are so light that they will not sink; then the process of solution is very slow. Solution is a valuable agent in bringing about chemical action during many processes of cooking and cleaning.

Water is a nearly universal solvent. It dissolves Solvents, larger quantities of more substances than any other liquid. Some solids, however, dissolve more readily in other liquids, as camphor in alcohol. Silver, copper and tin are not perceptibly dissolved in pure water, while most of their compounds, as nitrate of silver and sulphate of copper, are thus soluble. Lead dissolves more readily in pure water than in that containing some impurities. Gold may be dissolved in a warm mixture of two strong acids. Many of these metallic solutions which may be formed in cooking utensils and water pipes are poisonous, and a knowledge of them becomes a matter of great importance to all housekeepers.

A process of daily occurrence in the household greatly resembles solution. It consists in the taking up of water, which produces an increase of bulk or "swelling," but no true solution. Gelatine swells in cold water and may then be dissolved in hot water. Starch "jells" by taking up water; so we soak the cereals which consist largely of starch, that they may be more quickly acted upon by heat.

CHAPTER II. Elementary Chemistry

MOST substances with which we deal in ordinary life are compounds of two or more elementary constituents. The grain of wheat, the flesh of animals, the dangerous poison, are each capable of separation into simpler substances. Finally a substance is found which cannot be divided without losing its identity. The chemical element is that substance out of which nothing essentially different has ever yet been obtained.

Pure gold is an element from which nothing Elements. can be taken different from itself, but gold coin contains a little copper or silver or both. The oxygen of the air is an element. Air is a mixture of two or more elements. Oxygen and hydrogen, both gaseous elements, unite in certain proportions to form the chemical compound, water.

There are about eighty of these elements known to the chemist, while their compounds are infinite. For his convenience the chemist abbreviates the names of the elements into symbols which he uses instead of the names. Usually, the first or the first two letters of the Latin name are taken.

These symbols mean much more, however, than time saved, as we shall see.

Most of the elements unite with each other. Then in the resulting compounds, one or more elements may be exchanged for others, so that a multitude of combinations are formed out of few elementary substances. The bulk of our food, clothing and furniture is made up of only five or six of these elements, although about twenty of them enter into the compounds used in the household. The others are found in nature, in the chemical laboratory or in the physician's medicine case. A few are so rare as to be considered curiosities.

Every housewife should understand something of these chemical substances — their common forms, their nature and their reactions, that she may not be cheated out of time and money, and, more important still, that she may preserve the health of those for whom she cares.

All chemical changes are governed by laws. Under like conditions, like results follow. No chemical sleight of hand can make one pound of washing soda do the work of two pounds, or one pound of flour make a third more bread at one time than at another.

It has been assumed that all compounds are formed by the union of atoms — those smallest homogeneous particles of matter. Each atom has its definite weight, which remains constant. This weight is known in chemistry as "atomic weight." No single atom can be weighed by itself, but it is found that hydrogen is the lightest substance known, so the weight of its atom is called one. All other substances are compared with this unit, i. e., their atoms weigh one, two, three or more times the hydrogen atom.

Reckoned in this way the atom of oxygen £ hei £ i( { al weighs sixteen and the carbon atom twelve times as much as the atom of hydrogen. The symbol of an element, then, represents its constant atomic weight; so that, while the word oxygen means only the collection of properties to which is given the name, the symbol O indicates a definite quantity which is sixteen times the weight of the H atom.

The number of atoms used is indicated by a small figure placed below and at the right of the symbol. When no figure appears, one atom is understood. In a compound, the number of molecules is designated by a large figure at the left of the formula : H 2 S0 4 means one molecule containing two atoms of hydrogen, one of sulphur, four of oxygen. 4H 2 S0 4 means four molecules containing eight atoms of hydrogen, four of sulphur, sixteen of oxygen. A little chemical arithmetic is needed to compute the weight of these molecules. Molecular weight is the sum of the atomic weights of the constituent elements. Our chemical example then stands :

Two atoms of H= 2

One atom of S^ 32

Four atoms of O^ 64

One molecule of H 2 S0 4 =: 98 Four molecules of H 2 S0 4 =392

392 what? All weights are referred to the standard H ; so the four molecules weigh 392 times as much as the hydrogen atom.

The symbols, then, are the chemist's shorthand alphabet, or his sign language. The non-scientific reader is apt to look upon the acquisition of this sign language as the schoolboy regards the study of Chinese — as the work of a lifetime. He would be near the truth were he to attempt to remember the symbols of all the complicated compounds known and constantly increasing; but a study of the properties and combinations of the few which make the common substances of daily use need not frighten the most busy housewife, for they can be comprehended in a few hours of thoughtful reading. Then a little practice will make them as familiar as the recipe of her favorite cake. "To master the symbolical language of chemistry, so as to fully understand what it expresses, is a great step toward mastering the science."

Having thus prepared the ground and collected Laws oi materials, the foundation may be laid — i. e., the laws of chemical combination. It has been said that the elements unite with each other and exchange places one with another. In society there are persons whose powers of attraction toward others vary widely. In conversation upon any subject, one person may interest, with ease, one individual; another may hold two interested listeners; while a few, with rare gifts, may hold together a group of many. We say the last person has a stronger holding power than the other two. This may serve to illustrate what is known by experiment to be a fact among atoms. The chemist finds an atom of one element holding to itself one atom of a different element; another, holding two; while a third may hold three or more.

Chlorine will hold to itself only one atom of H, making HC1, muriatic acid; but O holds two — H 2 — water; N holds three — NH 3 — ammonia; and C, four — CH 4 — "fire damp.'*

Under different conditions, some elements show different powers of attraction toward the same element; so again this chemical society resembles social life. Sometimes N will hold to itself one atom of O, sometimes two, and sometimes three with an atom of H besides.

Exchange Value.

The chemist must understand all these holding powers, which he calls the valence of an element; but to him the housewife may leave the thorough knowledge, while she recognizes that by virtue of this valence, compounds are formed with widely different qualities; thus, H 2 is pure water, while H 2 2 , hydrogen peroxide, is a disinfectant and a bleaching agent; S0 2 , sulphur dioxide, used for bleaching straw and fabrics, also a germicide, is a gas; while S0 3 is a white crystalline solid.

Valence is a variable quality, but in uniting, or exchanging places with each other, the atoms of each element have a value which remains constant. This value is expressed in terms of a certain unit which chemists have chosen as a standard.

At the outposts of the Hudson's Bay Territory all trade is on a system of barter or exchange, and therefore a basis of value is necessary. The skin of a beaver is agreed upon as the unit from which to count all values. A red fox skin is worth two beaver skins ; a silver fox skin is worth four beaver skins. All the hunter's transactions are based upon these values. If he wishes to purchase a knife, he must pay four beaver skins; a gun will cost him three silver fox or twelve beaver skins.

The chemist's standard of value is the atomic weight of hydrogen. They choose this because it is the smallest relative weight known to enter into combination with other elements. Having once accepted this arbitrary choice, all values are counted from its value. For the convenience of the reader, this exchangeable value will be indicated by Roman numerals over the symbols in the formulae given in this book, although this practice is not universal.

The exchange value of other elements is found £o™ s bina " by experiment. For our present purpose, these elements may be divided into three classes with hydrogen for a connecting link.

Exchange Values.

Table I.

Some common elements which unite with H:

Chlorine CI 1

Iodine I 1

Bromine Br 1 1

Oxygen O 11 > +H 1

Sulphur S n

Nitrogen N nI

Carbon C™

H 1 unites with CI 1 , atom for atom, their values being the same. O n unites with two of H 1 , its value being twice that of H 1 ; while N m equals three of H 1 ; and C IV , four.

Table II.

Some common elements which unite with each other and with compounds of H.

Carbon C 1 ^

Oxygen O n

Sodium Na 1

Potassium K 1

Calcium Ca 11

Chlorine CI 1

Nitrogen N HI

Sulphur S«

Phosphorus P v

C™ unites with 2 n making C IV 2 n , carbon dioxide or carbonic acid gas; C IV 2 n unites with H 2 I O n forming H 2 I C iy 3 11 , carbonic acid gas in solution. Ca 11 unites with O n , forming Ca n O n , quicklime; Ca XI O n unites with H^O 11 , forming CanH^Oj, 11 , slaked lime.

Table III.

Some common elements which may be substituted for H in a compound, thereby making a new compound :

Sodium Na 1

Potassium K 1

Calcium Ca 11

Carbon C J V

Phosphorus P 111 or PV

Tin SnH r Sn™

Zinc Zn"

Sulphur S n

Copper Cu 11

Lead Pb"

Gold Auin

Aluminum Al 11 or A1 IV

H I C1 I is muriatic or hydrochloric acid. As Na 1 has the same value as H 1 , it may be substituted for it, and we have Na I Cl I , common salt. H 2 I C IV 3 11 is carbonic acid in solution. Na 2 * may be substituted for the H 2 X forming Na^C^Og 11 , the commercial soda ash. Soda ash added to water and allowed to crystallize from it gives the familiar "washing crystals." H I N III 3 n is nitric acid. One atom of K 1 will replace the H 1 , forming K I N III 3 n , or saltpetre.

Some of the compounds formed by the union Union and

x Exchange.

and exchange of these various elements are very familiar substances.

"In the laboratory we never mix our materials at random, but always weigh out the exact proportions . . . for, if the least excess of one or the other substance over the proportions indicated is taken, that excess will be wasted. It will not enter into the chemical change."* It is this exact-

*"The New Chemistry," p. 151.

ness in dealing with matter which gives to the study of chemistry its great value from an educational standpoint. In the economy of nature nothing is lost. Wood and coal burn in our stoves. The invisible product of their combustion, C IV 2 n , passes into the air, but adds a definite amount to the weight of the air. Twelve pounds of coal (free from ash) in burning take from the air thirty-two pounds of oxygen and give back to the air forty-four pounds of carbon dioxide.

Water is always composed of two atoms of hydrogen to one of oxygen, whether the quantity formed be one molecule or one million molecules. The water molecule, H^O 11 (atomic weights, H 2 T =2, O n =i6) weighs 18, then for every eighteen parts by weight of water, there will be two parts by weight of H 1 and sixteen parts by weight of O n .

C IV 2 n , carbon dioxide, has one atom of carbon and two atoms of oxygen in each molecule ; while by weight, twelve parts are C IV and thirty-two are O n . The exchanges and interchanges among the elements according to these two laws of value and weight form chemical reactions. The written expression of the reaction is called a chemical equation. In all chemical equations there is just as much weight represented on one side of the sign of equality {—) as on the other.

COOKING AND CLEANING.

C I v+0 2 II =Civo 2 n

12 + 32 Carbon. Oxygen.

HiCl* + NaiO n Hi =

Muriat- Caustic

ic Acid. Soda.

- 44 Carbon Dioxide.

Na^l 1 + HJO"

Sodium, Water.

Chloride or Common Salt.

This shows that the sumi of the weights of the two substances taken is equal to the sum of the weights of the new substances formed as the result of the reaction. These facts lead up to one of the fundamental laws of the present science of chemistry — the Law of Definite Proportions: In any chemical compound the elements ahvays unite in the same definite proportion by weight.

The atomic weights of elements united in a compound are then spoken of as the combining weights; thus, twelve and thirty-two are the combining weights of C IV and O n . Out of this first law grows a second — the Law of Multiple Proportions: When elements form more than one compound, they unite according to some multiple of their combining weights.

As we have noticed, sulphur and oxygen form different compounds — S0 2 and SO s — where the combining weights are thirty-two to thirty-two for the first and thirty-two to forty-eight for the second.

These two laws are the corner-stones upon which all reactions are built. If we wish to obtain forty-four pounds of carbon dioxide (carbonic acid gas) we may, according to our first law, write out the reaction which we know will take place.

c+o 2 =co 2

The combining weight of carbon is 12.

One atom= 12

The combining weight of oxygen is 16.

Twt> atoms= 32

Then we must take twelve pounds of carbon and thirty-two pounds of oxygen to make our desired forty-four pounds of gas.

Exchange of When more than two elements enter into corn-

Groups.

bination, it is common for two or more to band together. In such a case the group has an exchange value of its own, which is not the sum of the values of its separate elements, but which is a constant value, dependent upon their values in a way which it is not necessary to explain here. These partnerships will be included in brackets, as (SOJ 11 , (C0 3 ) n , (NO.) 1 . These groups do not represent actual compounds, which exist alone, like lyO 11 , IPCl 1 , C IV 2 n , N^Cl 1 ; but the group

COOKING AND CLEANING.

enclosed by the brackets passes from one compound into another as if it were one element. The numeral over the bracketed letters indicates the exchange value of the partnership, not the sum of the elements. A few illustrations will make this clearer.

Table IV.

Mineral acids and some of their common compounds :

HiQi Hi(N0 3 ) 1

Muriat- Nitricj

ic Acid. Acid.

Compounds :

NaiQi

Salt.

KJCNOs)!

Saltpetre.

H,i(SO0 n

Sulphuric Acid.

Ca«(SO0«

Plaster of Paris.

Carbonic Acid.

Marble.

Reactions among the above substances : H 2 i(S04) II +Caii(C0 3 ) II =Ca"(S04) n +H 2 i(C03) n H 2 i(SO 4 )n+2(Na I Q I )=Na,i(SO0 II +2(HiCli)i H 2 i(S04) II +NaiCl I =NaiHi(S04) II +HiCli