A System of Chemistry Volume 2

A System of Chemistry Volume 2

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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. 1810 edition. Excerpt: ...Philosophical Transactions for 1794. A piece of white lac, from 3 to 15 grains in weight, is probably produced by each insect. These pieces are of a grey colour, opaque, rough, and roundish. When white lac was purified by being strained through muslin, it was of a brown colour, brittle, hard, and had a bitterish taste. It melted in alcohol, and in water of the temperature of 145. In many of its properties it resembles beeswax, though it differs in others; and Dr Pearson supposes that both substances are composed of the same ingredients, but in different proportions. 1. Two thousand grains of white lac were exposed in Properties, such a degree of heat as was just sufficieht to melt them. As they grew soft and fluid, there oozed out 550 grains of a reddish watery liquid, which smelled like newly baken bread. To this liquid Dr Pearsonhas given the name of of laccic aeid. 2. It possesses the following properties i It turns paper stained with turnsol to a red colour. After being filtered, it has a slightly saltish taste with bitterness, but is not at all sour. When heated, it smells precisely like newly baken hot bread. The same liquid appear s on pressing the crude lac between the i fingers; and we are told that when newly gathered it is replete witfc juice. f Pearson's Transl. of the Chemical Ntmtaclalurc. Vol. Il y Book 11 Qn standing-, it grows somewhat turbid, and deposits Division II.' t a small quantity of sediment. Its specific gravity at the temperature of 60 is 1-025 A little of it having being evaporated till it grew very turbid, afforded on st inding small needle-shaped crystals in mucilaginous matter. Two hundred and fifty grains of it were poured into a very small retort and distilled. As the liquor grew warm, mucilage-like clouds...show more

Product details

  • Paperback | 160 pages
  • 189 x 246 x 9mm | 299g
  • Rarebooksclub.com
  • Miami Fl, United States
  • English
  • black & white illustrations
  • 1236600967
  • 9781236600967