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Table of Equivalents of Acids

This table is based on the foregoing table of The accuracy of the tests, when saturation is resorted to, depends greatly on the exact point of neutralization, as already remarked under the head of Acetimetry. The proper point is arrived at when the liquid, after being slightly heated, ceases to redden alkalis; so that, for instance, 1 equivalent (17 litmus, or does not alter the color of turmeric grains) of pure ammonia will exactly neutralpaper (see Test Papers) ; if it turns the lat- ize 1 equivalent (22 grains) dry carbonic acid, carbonic acid , ter brown, too much test-liquid has been &c. added, and the operation becomes useless.

A good method is to tint either the acid sample or the test-liquid with a few drops of litmus (see No. 71), when the reddish shade will gradually deepen to purple as the point of saturation is approached, and the blue color be restored as soon as that point is reached. 79. To test the strength of an Acid by Saturation. Place in a test tube 100 grains of the acid to be examined; if the acid be liquid, dilute it-if solid, dissolve it-in 6 or 8 times its weight of distilled water. Then exactly neutralize it with an alkali added drop by drop. The known quantity of alkali consumed for this purpose se represents an equivalent quantity of the actual acid contained in the test tube. The common practice is to dissolve 1 equivalent (see No. 80) of an alkaline test in water, and to make up the solution to 1000 grains (100 acidimetric divisions). The equivalent value of the test-liquid is then 100; hence, the quantity of the sample tested will bear the same proportion to the equiva- GRAINS.

Anhydrous acetic acid 51 Hydrated or crystallized acetic acid... 60 Dry benzoic acid. 113 Crystallized benzoic acid. 122 Dry boracic acid. 35 Crystallized boracic acid 62 Dry carbonic acid. 22 Dry citric acid. 58 Crystallized citric acid..

Dry hydrochloric acid. 67 36+ Liquid hydrochloric acid (sp.gr.1.16)..109 Dry malic acid...

Dry nitric acid. 58 54 " Liquid nitric acid (sp. gr. 1.5). 67 66 (sp. gr.1.42) 90 Dry oxalic acid. 36 Crystallized oxalic acid. 63 Dry sulphuric acid. 40 Liquid sulphuric acid (sp. gr. 1.845 49 Dry tartaric acid.

Crystallized tartaric acid. 66 75