SCIENCE AND INDUSTRY. 
It may be sold as such or further converted into acetome. Acetate of 
lime usually contains 80 per cent. of calcium acetate. When sodium 
acetate is required, and this has become an important product nowa- 
days in the manufacture of acetic anhydride, the distillate from the 
crude pyroligneous acid is absorbed in a solution of sodium carbonate 
instead of milk of lime.. The volatile constituents are distilled off 
and the residue is concentrated and finally evaporated to dryness. A. 
considerable amount of organic impurities which are always present 
give the product a brown colour, so that it is heated to 820 deg. C, in 
order to destroy the foreign matter. The crude sodium acetate as thus 
obtained is further purified by dissolving in water and recrystallizing. 
Acrtio Actin, 
The greatest proportion of the calcium acetate is converted into 
acetic acid. It is mixed with 95 per cent. sulphuric acid and distilled 
under reduced pressure. The crude calcium acetate is never free from 
impurities, and these react with the sulphuric acid to liberate oxides of 
sulphur. Hence by distilling under reduced pressure, the temperatures 
reached are lower, and in consequence the amount of sulphuric acid 
which is decomposed is greatly reduced. The strength of the acetic 
acid obtained varies with the type of still-head used. First runnings 
are from 25 to 50 per cent. But for the production of glacial acetic 
acid a second distillation is necessary, and an efficient rectifying column 
must be used. Weak acetic acid as obtained from wood products is 
frequently yellowish in colour. This is due to the presence of sulphur 
compounds formed during the distillation. Sulphur dioxide is often 
present in small quantity, and may be detected by its reducing action 
v 
on a dilute solution of potassium permanganate. 
The distillate obtained from the milk of lime liquors has the follow- 
ing composition :— 
Methyl alcohol Sh Ate .. 70 per cent. 
Acetone a3. a “68 + dy PLOS Pies es 
Aldehydes sa A )s Pee winy Ott inta artvine i 
Water a af pe ive Cone ter 
A separation of the constituents is effected by fractional distillation. 
The most important substance thus obtained is, of course, the methyl 
alcohol. Most of the uses for methyl alcohol are such that no ketone 
must be present. Thus in the production ‘of the monomethyl and di- 
methyl anilines, where aniline hydrochloric acid and methyl. alcohol - 
are heated together in an autoclave under pressure, any acetone which 
may be present would react with the aniline to form an insoluble com- 
pound, and at the same time triphenyl methane by-products would be 
formed. Acetone would also be an undesirable impurity in methyl 
alchol which is to be used for the production of formaldehyde. So that 
the fractional distillation has to be carefully carried out to obtain a 
methyl alcohol containing not more than -1 per cent. acetone... ., 
_ It will ‘thus be seen that directly from wood distillation, acctie acid, 
methyl alcohol, and acetone are obtained. But the same industry 
usually carries on the related manufactures of formaldehyde’ from 
methyl alcohol and acetone from calcium acetate. sat N AD) 
688 
