SUBSTANCE

FORMULA

SUBSTANCE

FORMULA

Water.........

H20

Calcium Oxide

(Lime)

Peroxide of Hydrogen

H2O2

CaO

Lime Water . . . .

CaOH

Sulphuric Acid . .

H2SO4

Calcium Carbonate

CaCO3

Sulphur Dioxide .

SO2

Calcium Hypochlorite (Chloride of Lime) ....

Ca(ClO)2

Hydrochloric Acid

HCl

Acetic Acid ....

C2H4O2

Sodium Thiosul-phite ("Hypo") .

Na2S2O3

Tartaric Acid . . .

C4H606

Cream of Tartar (Acid potassium tartrate) . . . .

KC4H5O6

Cane Sugar ....

C12H22O11

Milk Sugar ....

C12H22O11+H2O

Carbon Dioxide . .

CO2

Grape Sugar . . .

C6H12O6

Carbon Monoxide .

CO

Starch

(C6H10O5)x

Caustic Soda . . .

NaOH

Cellulose

(C6H10O5)y

Caustic Potash . .

KOH

Stearine (in fat) .

C3H5(O2C18H35 )3

Sodium Carbonate (Anhydrous) . .

Na2C03

Palmitin (in fat) .

C3H5(O2C16H31)3

Soap...

NaO2C18H35, NaO2C16H31, etc.

Sodium Carbonate ( Crystalline) (Washing Soda) .

Na2CO3+12H2O

Albumen . . .

(Not definitely known.)

Sodium Bicarbonate

NaHCO3

Alcohol......

C2H5OH

Wood Alcohol . .

CH3OH

Ammonia (gas) . .

NH3

Glycerine.......

C3H5(OH)3

Ammonium Hydrate (Ammonia

Water)...........

NH4OH

G'soline, N'phtha

C6H14, C7H18.

Benzine, etc. . .

C8H18, etc.

tested for fastness to light by exposing to direct sunlight for a day or two, saving a portion of the cloth as before for comparison. If the dye will stand direct sunlight without appreciable change for this length of time, it will not give much trouble by fading. Wall paper may be tested for fading in a similar way.

The industrial chemist always endeavors to test materials in a manner as nearly like the way they are to be used as possible. For example, if he were testing two samples of flour to be used for making bread, he might make up two small loaves, using carefully weighed quantities of each sample of flour and other materials and baking the loaves at one time, compare the result. In such cases it is usual to have a "standard" flour or other material to use for comparison.

This method of testing by comparison could often be used by housekeepers provided reasonable care were taken as to weights and conditions. Working thus, flour, baking powder, soap, spices, flavoring extracts, in fact almost all the raw materials of the kitchen and laundry could be tested.

The chemicals for househald use are chiefly acids, alkalies, and solvents for grease. Acids and alkalies are opposed to each other in their properties and if too much of either has been used, it may be rendered in-nocent or neutralized by the other; as when soda has turned black silk brown, acetic acid or vinegar will bring the color back.

Testing by Comparison

The acids which should be on the chemical shelf for the household are acetic, hydrochloric (muriatic), oxalic. Vinegar may be used in many cases instead of acetic acid, but vinegar contains coloring matter which stains delicate fabrics and it is better to use the purified acid. Hydrochloric and oxalic acids are strong acids and will harm most household materials if allowed to act for long time. Acetic acid is a weak acid and as it is volatile, evaporates without becoming concentrated as do the others.

Some bright blue flannels and other fabrics, when washed with soap or ammonia become changed or faded in color. If acetic acid or vinegar be added to the last rinsing water, the original appearance may be restored. Not all shades of blue are made by the same compounds, hence not all faded blues can be thus restored.

The use of these acids has been indicated in the previous pages, and there remains to be considered, only certain cautions. Hydrochloric acid is somewhat volatile. It will escape even around a glass stopper and will eat a cork stopper; therefore, either the glass stopper should be tied in with an impervious cover - rubber or parchment - or a rubber stopper used, for the escaping fumes will rust metals and eat fabrics.

Oxalic acid should be labeled Poison.

The bleaching agents, "chloride of lime" and Javelle water owe their beneficent effect to substances of an acid nature which are liberated from them. They should all be used in solution oniy, and should be kept in bottles with rubber stoppers.

Sulphurous acid gas, obtained by burning sulphur, will often remove spots which nothing else will touch. The amount given off from a burning sulphur match will often be sufficient to remove from the finger fruit stains or those made by black kid gloves.

The alkalies which are indispensable are:

1st. Ammonia - better that of the druggist than the often impure and always weak "household ammonia." The strong ammonia is best diluted about one-half, since it is very volatile, and much escapes into the air.

2nd. Potash and Caustic Soda, which are to be had at the grocers in small cans. The lye obtained from wood ashes owes its caustic and soap-making properties to potash. The caustics are corrosive in their action, and must be used with discretion.

Crystallized sodium carbonate, the sal-soda of the grocer, is chemically speaking a salt and not an alkali, but it gives all the effect of one, since the carbonic acid is so weak that it readily gives place to other substances.

Sal-soda is a very cheap chemical, since it is readily manufactured in large quantities, and forms the basis of most of the washing powders on the market. With grease, it forms a soap which is dissolved and carried away.

3rd. Borax is a compound of sodium with boric acid, and acts as a mild alkali. It is the safest of all the alkalies, and affects colored fabrics less than does ammonia.

Solvents for grease are alcohol, chloroform, ether, benzine, naphtha, gasolene - all volatile - kerosene and turpentine. Of these chloroform is the most costly, and is used chiefly for taking spots from delicate silks. Fabrics and colors not injured by water may be treated by alcohol or ether. Benzine, naphtha or gasolene are often sold, each under the name of the other. If care is taken to prevent the spreading of the ring, they can be safely used on any fabric. They do not mix with water, and are very inflammable.

The less volatile solvents are kerosene and turpentine. Kerosene is a valuable agent in the household, and since some of the dealers have provided a deodorized quality, it should find an even wider use. The lighter variety is better than the 150-degree fire test, which is the safe oil for lamps. As has been indicated in the preceding pages, the housewife will find many uses for this common substance.

On account of the purity and cheapness of kerosene, turpentine is less used than formerly, although it has its advantages.

These household chemicals should have their own closet or chest, as separate from other bottles as is the medicine chest, and especially should they be separated from it Many distressing accidents have occurred from swallowing ammonia by mistake.

In addition to these substances, certain others may be kept on hand, if the housewife has sufficient chemical knowledge to enable her to detect adulteration in the groceries and other materials which she buys.