38 



58.8 C. It is an excellent solvent for resins, gums, camphor, fats, 

 and gun cotton, and is largely used in the manufacture of smokeless 

 powder, the preparation of celluloid goods, chloroform, iodoform, 

 and sulphonal. 



In addition to that produced directly in the distillation of wood 

 and separated from methyl alcohol as above described, large quan- 

 tities are made from gray acetate of lime by dry distillation at high 

 temperature, decomposition taking place according to the following 

 formula: (C 2 H 3 O 2 ) 2 Ca= CaCO 3 + CH 3 .CO.CH 3 . The distillation and 

 decomposition is conducted in an iron retort, with constant stirring. 

 The distillation takes place in three stages : At first water containing 

 a small percentage of acetone comes over; in the second stage, when 

 the temperature of the mass has risen to 400 C., acetone oils are 

 obtained. The dark brown, highly inflammable distillate separates 

 into two layers on standing, the top layer consisting of the so-called 

 " heavy acetone oils" and the lower of acetone and light acetone oils 

 dissolved in water. The following table gives the percentage yield 

 of products obtained by the distillation of gray acetate of lime : 



Products obtained by distillation of gray acetate of lime. 



The yield of acetone is about 20 per cent of the calcium acetate, or 

 about 13 per cent when made from 40 per cent acetic acid. 



In preparing pure acetone the crude distillate obtained, which con- 

 tains higher ketones, aldehydes, etc., is treated with milk of lime and 

 allowed to stand for some time. The supernatant oily layer is diluted 

 with water and distilled in a column still, yielding as a main fraction a 

 nearly pure product (99 to 99.5 Tralles), which does not become 

 turbid when mixed with water. Another distillation removes traces 

 of aldehydes and empyreumatic materials. The first and last frac- 

 tions obtained in the above distillation, together with oils recovered 

 from the clarification with milk of .lime, are mixed and redistilled, 

 yielding another portion of commercial acetone. The residual oils 

 are the so-called acetone oils of commerce, known as light oils, boiling 

 between 75 and 130 C., and heavy oils boiling between 130 and 

 250 G. They may be used as denaturing agents, as a means for 

 purifying raw anthracene and in secret manufacturing processes. 



[Cir. 36] 



