How To Detect Adulterants In Coffee

I. Shake some ground coffee in cold water. Pure coffee usually floats on the surface, while ordinary adulterants sink; chicory colors the water a brownish red.

How To Test Extracts. 1. Vanilla

Evaporate a quantity of the extract to about 1/3 its original volume. Add enough water to restore the first volume. The resins which give the flavor will appear as a brown feathery mass which sinks to the bottom or "precipitates." If a precipitate is formed, add a few drops of hydrochloric acid, stir, filter through a small funnel in which filter paper is folded and wash out the acid by pouring water through the filter three or four times. Dissolve the precipitate on the paper with a little alcohol. Divide this into two portions. To one add a piece of ferric alum, and to the other a few drops of hydrochloric acid. If neither produces more than a slight change of color, the pure extract of the vanilla bean was used. If there is a distinct change of color, extracts from other sources are present.

2. Lemon

To a test tube nearly filled with water add I t of the extract. If the real lemon is present it will come out of solution and will give a turbid appearance to the solution, and will form an oily layer on the top of the water. If the solution remains clear after diluting with water, very little if any oil of lemon is present.

How To Test For Sulphides

1. Wet the sample of meat or other food with water and stir well.

2. Pour into a flask or wide mouth bottle and add small pieces of pure zinc and a little hydrochloric acid. If sulphide preservatives are present the unpleasant odor of hydrogen sulphide will be noticed. To test this dip a piece of filter paper into lead acetate solution and suspend it in the flask. A black color on the paper indicates the presence of hydrogen sulphide.

How To Detect Alum In Baking Powder

1. Put some logwood chips in a small agate-ware dish, cover with water, and bring to a boil. Throw the water away. Do this three times, then save the fourth extract.

2. Fill a test tube about half full of water and add l t baking powder. Warm it and shake till effervescence ceases, then add a drop or two of hydrochloric acid' to make the solution acid.

3. To this solution add 4 or 5 drops of the logwood extract. A bluish red color indicates the presence of alum. A yellow color shows its absence. Try ,a small bit of alum dissolved in water with the logwood extract to become familiar with the color.

How To Test Ice Cream

1. For glucose:

Add an equal quantity of Fehling's solution to 1 t of the cream to be tested and boil. If a red precipitate appears glucose is present.

2. For starch:

Add a few drops of tincture of iodine. A dark blue color indicates the presence of starch.

3. For gelatine:

To 3 T of ice cream add 6 T of cold water and 3 T of acid mercuric nitrate. Shake vigorously, then let stand 5 minutes. Filter through filter paper. If much gelatine be present, it will be impossible to get a clear solution. Mix a portion of the filtrate with an equal amount of a strong ("saturated") water solution of picric acid. If any gelatine be present a yellow precipitate will be produced immediately.