Elements of agricultural chemistry, in a course of lectures for the Board of Agriculture / By Sir Humphry Davy.

  • Davy, Humphry, Sir, 1778-1829.
Date:
1813
Catalogue details

Licence: Public Domain Mark

Credit: Elements of agricultural chemistry, in a course of lectures for the Board of Agriculture / By Sir Humphry Davy. Source: Wellcome Collection.

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    Hydrogene - - 12,583 or. Carbon - 76,811 Water or its elements - 12,052 Hydrogene - 11,137 From these results, if resin be a definite compound, it may be supposed to consist of 8 proportions of carbon, 12 of hydrogene, and 1 of oxygene. Resins are used for a variety of purposes. Tar and pitch principally consist of resin, in a partially decomposed state. Tar is made by the slow combustion of the fir; and pitch by the eva- poration of the more volatile parts of tar. Resins are employed as varnishes, and for these purposes are dissolved in alcohol or oils. Copal forms one of the finest. It may be made by boiling it in powder with oil of rosemary, and then adding alcohol to the solution. ' 14. Camphor is procured by distilling the wood of the cam- phor tree (Laurus campliora,) which grows in Japan. It is a very volatile body* and may be purified by distillation. Camphor is a white, brittle, semitransparent substance, having a peculiar odour, and a strong acrid taste. It is very slightly solu- ble in water; more than 100,000 parts of water are required to dissolve 1 part of camphor. It is very soluble in alcohol; and by adding water in small quantities at a time to the solution of camphor in alcohol, the camphor separates in a crystallised form. It is soluble in nitric acid, and is separated from it by water.