ACIDIMETRY.

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ammonia marks upon the metrical hydrometer the degree 0^94, that is, 1 c.c.weighs o'94 grm., the 5 c.c. will weigh 0^94 X 5 = 47 grms. And as the 47 grms.contain 0^697 grm. of caustic ammonia, the equation 47 : o'6g7 = ioo : xgives ;r = i4’8 per cent of caustic ammonia. That is, that 100 lbs. of the liquidammonia contains I4'8 lbs. of caustic ammonia and 85’2 lbs. of water andimpurities.

Acidimetry.

Alkalimetry and acidimetry are charadterised by precisely the same methods ;a normal acid being used to estimate in the one case the percentage ofalkali, and a normal alkali in the other to estimate the percentage of pure acidcontained in an acid solution.

The litmus solution is, in the same manner as in alkalimetry, employed asan indicator. 1 c.c. of normal soda solution contains o - 03i of caustic soda,and will neutralise of—

Sulphuric acid.C040 grm.

Hydrochloric acid.C036 ,,

Nitric acid .°'°54 >1

The specific gravity of an acid is determined by the hydrometer, and fromthe specific gravity the percentage of pure acid can be obtained.