A System of Instruction in Quantitative Chemical Analysis (Paperback)

This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1882 edition. Excerpt: ...ammonia, warm gently, and filter through a very small filter into a weighable platinum vessel. Evaporate to dryness on a water-bath, heat to incipient fusion of the alkali chlorides, and after cooling weigh. Prof. Smrrn's method is the most convenient of all methods for extracting alkalies from silicates, and is universally applicable, except perhaps in presence of boric acid. Vhen carried out as here described, the results are sufiieiently accurate in most cases. If, however, the silicate is rich in alkalies, a loss amounting to 0'1 or ' 0'2 per cent of the mineral is possible. If great accuracy is desired in such cases, a repetition of the whole process may be applied to the residue left by treatment of the ignited mass with water. It need hardly be mentioned that unless care be taken to use reagents perfectly free from soda and to avoid action of solutions on glass, an amount of soda may be introduced from these sources equal to 0'1 or 0'2 per cent of the silicate I. Determination. Chlorine may be determined very accurately in the gravimetric as well as in the volumetric way. ' a. Graoiwnetric Jllet/zod.--Determinatz'on as Silver (llzloride. Solution of silver nitrate, mixed with some nitric acid, is added in excess to the solution of the chloride, the precipitated cdaloride is made to unite by heating and agitating, washed by decantation and filtration, dried, and ignited. The details of the process have been given in 115, 1, a. Care must be taken not to heat the solution mixed with nitric acid, before the nitrate of silver has been added in excess. As soon as the latter is present in excess, the silver chloride separates immediately and completely upon shaking or stirring, and the supernatant fluid becomes perfectly...