MANUFACTURE OF WOOD-VINEGAR. 247 



C 3 H 6 O 2 , butyric acid, C 4 H 8 O 2 , valerianic acid, C 5 H 10 O 2 , and caproic 

 acid, C 6 H ]2 O 2 . 



By decomposing the above-mentioned salt-mass with concen- 

 trated sulphuric acid, a black oily layer consisting of a mixture of 

 the above acids separates on the surface. They are but incom- 

 pletely separated by fractional distillation, the separation, however, 

 succeeding better by converting them into compound ethers and 

 subjecting the mixture of these to fractional distillation. 



According to Vincent, 100 parts of syrupy mother-lye are 

 mixed with 20 of 95 per cent, alcohol, and after gradually adding 

 70 parts of concentrated sulphuric acid, the whole is allowed to 

 cool. After some time a black layer separates on the surface, 

 which is taken off, and after shaking with weak soda solution 

 until it shows no acid reaction, and dephlegmating over calcium 

 chloride, is carefully distilled, the distillates passing over between 

 131 and 136.4 F., 165 and 170.6, 203 and 208.4, 237.2 

 and 246.2, 271.4 and 276.8, and 323.6 and 329 being 

 collected by themselves. By decomposing these products with 

 barium-water alcohol is formed, which is removed by evaporation, 

 and the barium salts of the fatty acids. The latter are crystallized, 

 and then the acids separated by sulphuric acid. The first 

 distillate yields formic acid, the second propionic acid, etc. 



Manner of Obtaining Wood Spirit (Methyl Alcohol). 



Crude wood spirit is a mixture of methyl alcohol with methyl 

 acetate, dimethylacetal, acetone, inetacetone, aldehyde, various 

 hydrocarbons, acetates of ammonium and methylamiue, and free 

 acetic acid. 



These substances cannot be separated by fractional distillation 

 alone, because the boiling point of some of them is nearly the 

 same (methyl alcohol 152.6 F., dimethylacetal 147.2, acetone 

 132.8, methyl acetate 131). The crude wood spirit is digested 

 in a still with slaked lime, whereby, with the development of 

 considerable heat, the free acetic acid always present combines 

 with the lime ; ammonia and methylamine are also evolved, and 

 the methyl acetate is gradually decomposed into calcium acetate 

 and methyl alcohol. (By the action of the 



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