Elementary quantitative analysis / by Alexander Classen ; translated, with additions, by Edgar F. Smith.

  • Classen, Alexander, 1843-1934.
Date:
1878
Catalogue details

Licence: Public Domain Mark

Credit: Elementary quantitative analysis / by Alexander Classen ; translated, with additions, by Edgar F. Smith. Source: Wellcome Collection.

    19/352 (page 15)
    lire pliiced a few drops of concentrated sulphuric acid, an equal amount of water and a smaU portion of strong nitric acid. The crucible is gradually heated upon a hot iron plate and the excess of acid evaporated, leaving finally pure copper sulphate, which may be weighed as such; or, the crucible is heated strongly over a Bunsen burner and cupric oxide formed. The crucible should be covered during the operation, and the salt stirred from time to time with a platinum wire. The method was proposed by Dr. Genth, and affords accurate results. The amount of copper in cupric oxide is readily calculated from the formula— CuO : Cu : : wt. CuO : x.'] Sulphuric Acid Determination. —Thx^ is based upon the insolubility of barium sulphate in hot water and strongly diluted acids. The acid in this compound is esti- mated by dissolving about .5 grm. of the salt in water, acidulating the solution with a few drops of hydrochloric acid and boiling. Barium chloride is added as long as a precipitate of barium sulphate is formed, and the solution boiled and stirred for some time after complete precipita- tion has been effected. Proceed as above described, when the barium sulphate has settled, washing the precipitate upon the filter with hot water until silver nitrate produces no turbidity in the washings. The dried precipitate is treated the same as the cupric oxide. The barium sul- phate obtained in this manner generally contains weigha- ble quantities of barium chloride—which were not removed by washing ; therefore digest the weighed precipitate with dilute hydrochloric acid, filter through a small filter, and again wash the precipitate perfectly with hot water, by decantation, ignite and weigh.