Home › Tests Or Reagents › To Test Arrow-Root

To Test Arrow-Root

Genuine arrow-root is odorless and tasteless, and produces a sort of crackling noise when pressed or rubbed, and emits no peculiar odor when mixed with muriatic acid. Stirred up in a precipitated in water containing carbonates, mortar with double its weight of a mixture of equal parts of aqua-fortis and water, it does not become gelatinous and adhesive in less than 15 minutes. chlorides, or sulphates. The degree of hardness of water depends on the amount of carbonate of lime held in it in solution, and is ascertained as follows: Dissolve 1 drachm finest white soap in 1 pint proof spirit; so ad- 4383. To Detect Arsenic in Colored Paper. Take a fragment of the paper and just the strength (if not already so) that exput it into a solution of ammonia. If arsenic actly 32 measures are required to be added to be present the liquid will assume a bluish 100 measures of the standard solution of color. In case a further test is required, pour chloride of calcium (see No. 4786), before a a little of the ammoniacal solution on crystals lather can be produced. Every measure of of nitrate of silver, and arsenic, if present, will show itself by leaving a yellow deposit on the crystals. As arsenic is used in coloring all qualities of paper, from the cheapest to the costliest, a knowledge of this test will be of service. this test solution of soap and alcohol, which is required to produce the same effect on 100 measures of a sample of hard water, represents grain of carbonate of lime or of hardness; 2 measures equal 1° of hardness or 1 grain of carbonate per gallon, &c.