ACETATES AND THEIR MANUFACTURE. 271 



have a bitter, salty taste. They are decomposed by heat into 

 acetone and calcium carbonate. A mixture of this salt and of 

 potassium oxalate gives, on heating, propylene (C 3 H 6 ), while a 

 mixture of carbonates remains behind. By the dry distillation 

 of equal equivalents of acetate and benzoate of calcium aceto- 

 phenone (C 8 H 8 O) is obtained, which by treatment with nitric acid 

 is converted into nitro-acephotenone (C 8 H 7 NO 3 ). By heating the 

 latter with zinc-dust and soda-lime, Emmerling and Engler claim 

 to have obtained artificial indigo-blue. But the quantity of the 

 latter thus obtained is always very small, and it appears to be 

 very difficult to ascertain the precise condition under which the 

 transformation takes place. 



With calcium chloride calcium acetate enters into a crystal- 

 lizable combination ; it also dissolves some sulphate of lead. 



Barium acetate (C 2 H 3 O 2 ) 2 Ba+lJH 2 O. This substance is pre- 

 pared from barium carbonate or barium sulphide and dilute acetic 

 acid. Since barium carbonate, which is found native as witherite, 

 and barium sulphide, which is prepared by heating barium sul- 

 phate with bituminous coal, always contain iron and this iron 

 passes into solution, it is separated by adding some barium water 

 after the point of neutralization is reached. The solution is then 

 filtered and the filtrate again neutralized with acetic acid. 



At a low temperature the solution yields colorless crystals 

 derived from a rhombic prism ; they are extremely deliquescent, 

 readily soluble in water, but with difficulty in ordinary alcohol 

 and almost insoluble in absolute alcohol. They show a slight 

 alkaline reaction, contain 3 equivalents (17.5 per cent.) of water, 

 and are isomorphous with normal acetate of lead (lead sugar), to 

 be described later on. By allowing the concentrated solution to 

 crystallize at a somewhat higher temperature the salt absorbs, 

 however, only 1 equivalent (6.5 per cent.) of water. 



By mixing a concentrated solution of the salt with sulphuric 

 acid, the barium sulphate does not separate in the ordinary form 

 of a fine white powder, but as a semi-transparent, gelatinous mass 

 which retains acetic acid ; for this reason barium acetate is not 

 suitable for obtaining strong acetic acid. 



When subjected to dry distillation barium acetate does not 

 yield acetic acid, but only acetone (and very little empyreumatic 



