A dictionary of chemistry and the allied branches of other sciences Volume 3 - Tapa blanda

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1871 Excerpt: ...absolute alcohol, and crystallised from solution in a small quantity of hot water,'tyrosine then separating first, and the motherliquor afterwards yielding leucine, tolerably pure but not quite wliite. It must therefore be dissolved iu hot water; digested with a small quantity of hydrated oxide of lead; the liquid filtered; the filtrate freed from lead by sulphydric acid, and the crystallised leucine further treated with animal charcoal (Hinterberger, Ann. Ch. Pharm. lxxi. 72). H. Schwanert (ibid. cii. 221) boils 2 lbs. of horn-shavings with 6 lbs. sulphuric acid and 13 lbs. water for 24 hours, renewing the water as it evaporates, then supersaturates with lime, and, after filtering off the gypsum, evaporates the filtrate to 12 lbs. and mixes it with a quantity Of oxalic acid sufficient to produce a slight acid reaction. The liquid filtered from calcic oxalate, and evaporated till a crystalline film forms upon its surface, deposits groups of yellowish lamina? of leucine mixed with tyrosine, more df which crystals may be obtained by evaporating the mother-liquor. The crystalline mass is then dissolved in such a quantity of hot water that the solution on cooling yields crystals of tyrosine only; the leucine solution is then decolorised with animal charcoal, evaporated,' and the leucine which separates is purified by pressure and recrystallisation from hot alcohol. Waaga(Ann. Ch.Pharm.cxviii. 295) proceeds in the same way as Schwanert, excepting that, after precipitating the last portions of lime with oxalic acid, he mixes the filtrate with sulphate of copper, precipitates the copper with sulphydric acid; evaporates the filtered liquid which is then nearly colourless, to the crystallising point; recrystallises the separated leucine from water and dilute alcohol...