54 THE BUTYRIC ACID GROUP. 



colourless, oily fluid, which at a low temperature solidifies in a 

 crystalline form, boils at about 140, has a peculiar sauer-kraut-like 

 taste, and in its general character deports itself like the acids of 

 this group ; it is not perfectly soluble in a small quantity of water, 

 but forms oily drops on it. 



Composition. According to the above formula it consists of : 



Carbon 6 atoms .... 48'649 



Hydrogen 5 .... 6'757 



Oxygen 3 .... 32'432 



Water 1 .... 12-162 



100-000 



The atomic weight of the hypothetical anhydrous acid = 815*5 ; 

 its saturating capacity = 12*31. 



According to the investigations of Kolbe, to which we have 

 already referred, this acid may, or indeed must be regarded as 

 ethyloxalic acid = C 4 H 5 .C 2 O 3 .HO. 



Combinations. With bases this acid forms soluble salts of a fatty 

 and glistening appearance, some of them also conveying a fatty 

 feeling to the touch. 



M etacetonate of. baryta crystallises in small rectangular octo- 

 hedra or rectangular prisms with oblique terminal surfaces. 



Metaceionate of silver forms glistening white granules or small 

 prisms, which are little changed by the action of light, are difficult 

 of solution in water, and when heated fuse, and at length noise- 

 lessly smoulder away. 



Metacetonate of oxide of ethyl in contact with ammonia 

 becomes converted into the colourless crystalline substance called 

 metacetamide, H 2 N. C 6 H 5 O 2 , which, by the agency of anhydrous 

 phosphoric acid, is converted, more easily even than metacetonate 

 of ammonia, into cyanide of ethyl. 



Metacetone, C 6 H 5 O, cannot be obtained from metacetonic acid, 

 but is yielded by the decomposition of one part of sugar or starch 

 with three parts of caustic lime; it forms a colourless, oily, volatile 

 fluid that is essentially different from oxide of cenyl which is isomeric 

 with it. 



Aldehyde of metacetonic acid, C 6 H 5 O.HO, was discovered by 

 Guckelberger,* among the products of distillation, during the 

 oxidation of nitrogenous matters by sulphuric acid and peroxide of 

 manganese ; it is a colourless fluid, having an ethereal odour ; its 

 specific gravity = 0'79j it boils at about 50, is miscible with water 



* Ann. d. Ch. u. Pharm. Bd. 64, S. 46 ff. 



