Synopsis
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. 1905 Excerpt: ...most to be recommended, while Procter and Searle's method (Wiss. Beilage 1901, p. 65) is simple and reliable with careful manipulation, but in presence of sulphates of iron, alumina, or ammonia may give misleading results. It is best carried out as follows:--4 grm. of the leather is placed in a platinum or porcelain basin, and moistened with 20 c.c. of N/10 sodium carbonate solution and evaporated to dryness on the water bath, and then gently ignited till completely carbonised, but not reduced to a white ash. The residue is powdered and treated with 30 c.c. of N/10 HC1, made up to 100 c.c, 50 c.c. filtered off, and titrated with N/10 soda solution in presence of methyl orange. The excess of soda solution which is required over 5 c.c. represents the free sulphuric acid of 2 grm. of leather and each c.c of soda solution over 5 corresponds to o 245 per cent If less than 5 c.c. is required it simply indicates the presence of lime or some other alkaline bases in the leather, and may be disregarded. The experiments thus far were made with roughtanned skins only. It was now necessary to enquire whether the ordinary methods of dyeing and finishing leather in any way impaired its wearing qualities. For this purpose calf, sheep, goat, seal, and pig skins were obtained in the rough or "crust" condition, and each skin was divided into four portions, of which the first was retained in its rough tanned state; the second was struck out, dyed, freed from superfluous dye by rinsing in water, and dried out; the third portion was struck out, dyed and finished in the usual manner, being glazed by friction after applying an ordinary albumen seasoning, no acid being added to the dye-bath to develop the colour; while the fourth portion was similarly struck out, dyed wit...
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