Encyclopaedia Britannica Volume 7 (Paperback)

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. 1823 Excerpt: ...of carbonaceous matter. The liquid in which the wool had been boiled being evaporated, yielded only a few grains of alum; what remained would not crystallize. This being redissolved and precipitated by means of an alkali, the alumina which was thrown down was of a blate colour, became black when placed on red-hot coals, and emitted alkaline vapours. In this experiment it appears that Uie alum was decomposed by the wool, and part of the alumina had combined with its most detached filaments which were least retained by the force of aggregation; that part of its animal substance had been dis solved and precipitated by the alkali, from the triple Of compound. dani 77. The same experiment was repeated with half' / an ounce of alum and two drams of tartar; but no precipitation followed. A small portion of the tartar, and some irregular crystals of alum, were obtained by crystallization: the remainder refused to crystallize; but being diluted with water, precipitated by potash, and evaporated, it yielded a salt which burned like tartar. The wool which was boiled with the alum had a harsh feel; but the other retained all its softness. The first, after being subjected to the process of maddering, had a duller and lighter tint; but the colour of the latter was fuller and brighter. 78. In the first of these experimente the wool had effected a decomposition of the alum, had united with part of the alumina; and even part of the alum which retained its alumina had dissolved some portion of the animal matter. In the second expeiiment it appears, that the tartar and alum, between which there seems to exist a balance of affinities, can only act on each other by the intermediate action of the wool. The principal use of the tartar seems to be to moderate the action of...