Plattner's manual of qualitative and quantitative analysis with the blowpipe; . a little retort, the short arm about 3 cm. in length, is putan intimate mixture of grm. of the assay substance with grm. of finely powdered litharge, and the lower end is graduallyheated over the spirit-lamp, provided with a chimney, until thewhole mass is fused and the glass begins to soften. The moisturethat may be present condenses in the middle of the tube, while themercury will settle as a thin film, sometimes scarcely perceptible,upon the sides of the glass. When all of the mercury has beensubl
Plattner's manual of qualitative and quantitative analysis with the blowpipe; . a little retort, the short arm about 3 cm. in length, is putan intimate mixture of grm. of the assay substance with grm. of finely powdered litharge, and the lower end is graduallyheated over the spirit-lamp, provided with a chimney, until thewhole mass is fused and the glass begins to soften. The moisturethat may be present condenses in the middle of the tube, while themercury will settle as a thin film, sometimes scarcely perceptible,upon the sides of the glass. When all of the mercury has beensublimed, the tube is carefully heated so as to concentrate the mer-cury, as much as possible, to a ring at i, the tube is allowed to cool,cut off with a file close to the ring, and the mercury then brushedtogether to one drop and transferred to a weighed capsule. b. Method of Kiistel. This method is given in the Polytechn. CentralU., 1874, p. poorer ores, with a few per cent, of silver, 100 mgr. are taken;of richer ores, 50 mgr. With the aid of a long, smooth paper strip. THE ASSAY FOK MERCUKT. 443 the ore is placed in the lower end, a, of a tube, Fig. 87, and uponit is put a three- or four-fold volume of perfectly dry soda I. Finally, a spiral of thin gold foil, of 300 to 400 mgr. in weight,exactly weighed. The tube is heated in a horizontal position, atthe closed end, over a spirit-lamp, and afterwards for a fewminutes is heated with the blowpipe flame, so that the mercurymay bo entirely volatilized and may combine with the gold. Anyglobules of mercury which may condense on the tube are gatheredby rolling the gold spiral here and there. The spiral is then with-drawn by means of a wire and weighed. Should any water condenseon the gold the latter is dried a short time in a glass over boilingwater. When the mercury is combined with chlorine, as in amalgama-tion residues, soda must also be used (about five volumes) becausechloride of mercury is not decomposed by oxide of lead
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Keywords: ., bookcentury1900, bookdecade1900, bookpublishernewyo, bookyear1902
