MANUFACTURE OF WOOD-VINEGAR. 249 



feet in diameter, and with a correctly conducted influx of water, 

 a product of 0.816 specific gravity is obtained by one operation 

 from crude wood spirit of 0.965 specific gravity. 



This product can be used for many purposes, for instance in the 

 preparation of varnishes. It is, however, not entirely pure, it 

 being rendered turbid by water which is due to a content of the 

 previously-mentioned hydrocarbons ; it further contains some 

 acetone, methyl acetate, aldehyde, ammonia, methylamine, and 

 is not fit for the fabrication of aniline colors. 



For further purification this rectified wood-spirit is diluted 

 with water until it shows a specific gravity of 0.934 and is then 

 allowed to rest a few days, when the greater portion of the hydro- 

 carbons has separated as an oily layer on the top. The clear fluid 

 is now again rectified with an addition of 2 to 3 per cent, of lime, 

 whereby a distillate is obtained which does not become turbid 

 with water but turns yellow in time. 



But neither this twice-rectified Avood-spirit is suitable for all 

 purposes, for instance, not for the preparation of methyl iodide. 

 To remove traces of ammonia and methylamine and to precipitate 

 the last particles of tarry substances, it is again rectified after 

 adding some sulphuric acid, this time, however, in a distilling 

 apparatus standing in a water-bath, whereby a temperature of 

 147.2 to 152.6 is sought to be maintained. One cubic metre 

 (35.31 cubic feet) of wood yields 2 to 3 quarts of methyl alcohol 

 which is not rendered turbid by water. 



For the purification of wood-spirit on a small scale, the above- 

 mentioned property of methyl alcohol to form a solid crystalliz- 

 able combination with calcium chloride can be utilized. Mix 

 the wood-spirit once rectified over lime with dry powdered cal- 

 cium chloride, pour oif the oily layer of foreign substances, which 

 separates, after some standing, upon the surface of the solid com- 

 bination formed, aud heat the solid body in a water-bath to 

 212 F. It is not decomposed at this temperature, while the 

 still-adhering impurities at least partially volatilize. Mix the dry 

 residue with water, whereby the combination is broken np, and 

 distill in a water-bath ; the distillate is quite pure methyl alcohol. 



The examination of commercial wood-spirit extends chiefly to 

 the presence or absence of the previously-mentioned hydro- 



