PYROXYLIC SPIRIT 



687 



A wood-spirit which refuses to dissolve sandarach may often be rendered a good 

 solvent by adding from 5 to 7 per cent, of acetone. See ACETONE. 



When wood-spirit is required in a state of extreme purity for the purpose of 

 research, it may be obtained by distilling oxalate of methyle with water. Oxalato of 

 methyle, or methyle oxalic ether may be prepared by distilling equal parts of 

 sulphuric acid, oxalic acid, and wood-spirit. The distillate when evaporated very 

 gently yields crystals of the compound in question. As it does not volatilise below 

 322 F., the retort containing the materials for its preparation requires to be pretty 

 strongly heated to bring the ether over. It may be purified by sublimation from 

 oxide of lead. 



Pure methylic alcohol is a colourless transparent liquid, neutral, very inflammable, 

 burning with a blue flame like common alcohol. It has a very nauseous flavour, 

 and is fiery in the mouth. It dissolves in any proportion in water, alcohol, or 

 ether, and is a good solvent for fatty bodies and certain resins. It is miscible with 

 essential oils. 



Wood-spirit may be detected even when greatly diluted with alcohol, by the brown 

 colour which it assumes in presence of solid caustic potash. Even when alcohol con- 

 tains only 2 per cent, of wood-spirit, it acquires a yellow tint in ten minutes on 

 addition of powdered caustic potash. In half an hour the colour becomes brown. 



According to Mr. Maurice Scanlan, wood-spirit may be distinguished from acetone 

 (with which it appears to have sometimes been confounded in medicine), by the 

 action of a saturated solution of chloride of calcium, which readily mixes with the 

 former, but separates immediately from the latter. 



Wood-spirit is but seldom employed now in the arts, as it is generally cheaper and 

 more convenient to use the mixture of 90 parts of spirit of wine with 10 parts of 

 purified wood-spirit, which is now permitted by Government to be employed free of 

 auty under the title of ' methylated spirit.' 



The following table contains the percentages of pure wood-spirit of the specific 

 gravity 0-8136 in various mixtures ; the temperature at which the experiments 

 must be made to correspond with the above table being 60 F. 



According to M. Deville, the above table is not absolutely correct, the spirit used by 

 Dr. Ure not having been entirely free from water. M. Seville's numbers are as follow: 



Percentage of 

 Specific gravity wood-spirit 



0-8070 100 



0-8371 90 



0-8619 80 



0-8873 70 



