A few of these simple tests are given with the chemicals needed.

Directions for Using the Housekeeper's Laboratory.

When directed to make a solution acid or alkaline, always test it by means of the litmus paper:

Blue turned to red means acid. Red turned to blue means alkaline.

Only by following the directions can the test be relied upon. Under other circumstances than those given, the results may mean something else.

Use the acids in glass or china vessels only. Metals may be attacked. Do not touch brass with ammonia or marble with acid. Aluminum is quickly corroded by the alkalies.

Heating or burning a substance often gives evidence of its character. Organic solids will char, leaving charcoal (carbon) when heated and will disappear completely when burned. Some salts melt; others do not.

All the carbonates that the housewife is likely to meet will give an effervescence of carbon dioxide with muriatic acid and most of them with acetic acid.

Substances of an acid nature will effervesce with a solution of cooking soda. The test will be more delicate if the solutions are warm.

To test for sulphuric acid or soluble sulphate in soda, cream of tartar, baking powder, vinegar, sugar or syrup: Add muriatic acid to the solution (if the insoluble part is sulphate of lime, it will dissolve in the acid on heating), then add barium chloride. A heavy white precipitate proves the presence of sulphuric acid, either free or combined. If the solution is not distinctly acid at first, it is not free.

To test for lime in cream of tartar, baking powder, sugar or syrup: Make the solution alkaline with ammonia and ammonium oxalate. A fine white precipitate proves the presence of lime. Good cream of tartar will dissolve in boiling water, and will show only slight cloudiness when the test for lime is applied.

To test for phosphates in cream of tartar or baking powder: Make acid by nitric acid, and add ammonium molybdate. A fine yellow precipitate or yellow color proves the presence of phosphates.

To test for chlorides in soda, baking powder, sugar, syrup or water: Make the solution (a fresh portion) acid with nitric acid, and add silver nitrate. A white curdy precipitate or a cloudiness indicates chlorides.

To test for ammonia in baking powder: Add a small lump of caustic soda to a strong water solution. Red litmus will turn blue in the steam, on heating.

To test for alum in cream of tartar, baking powder or bread: Prepare a fresh decoction of logwood; add a few drops of this to the solution or substance, and render acid by means of acetic acid. A yellow color in the acid solution proves absence of alum. A bluish or purplish red, more or less decided, means more or less alum.

To test for starch in any mixture which has been cooked, simply moisten with dilute tincture of iodine such as is kept by the druggists. An intense blue color will show the presence of even a minute quantity of starch. If the substance has not been heated, boil a portion and let cool and then test with a few drops of iodine solution. Heat destroys the blue color of iodine with starch and therefore the test must be made in cold solutions.

If the label of a washing powder claims it to be something new, and requires that it be used without soda, as soda injures 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 effervescence 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 appear and complete the proof. If the acid is added drop by drop, until no more effervescence 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. Acetic acid or a solution of oxalic acid may be used in place of the muriatic acid.

If some very costly silver polishing powder is offered as superior to all other powders, a drop or two of muriatic acid or of warm vinegar will decide whether or not it is chalk or whiting by the effervescence or liberation of the carbonic acid gas.

In making all the foregoing tests, it is well to observe the effect of the chemicals used on the substance to be tested for, and so become familiar with the characteristic color or appearance of the test. For example, before testing a washing powder, add a little acid to a soap solution and observe the greasy film produced, and in testing for alum add a very little alum solution to some flour and test with the logwood solution, noting the color given. This procedure will lead to more reliable results.

Caution! Use a new solution of a fresh portion of the first one for each new test and follow directions exactly. This is essential to remember.

Sample Tests