BUTYRIC ACID. 57 



157; its specific gravity at 0=0*9886; when inflamed, it burns 

 like an ethereal oil. 



Composition. According to the above formula it consists of : 



Carbon 8 atoms .... 54-545 



Hydrogen 7 .... 7'955 



Oxygen 3 .... 27'273 



Water 1 .... 10'227 



100-000 



The atomic weight of the hypothetical anhydrous acid=987'5 ; 

 its saturating capacity = 1 0*1 26. 



According to the beautiful investigations of Kolbe, butyric acid 

 may be regarded as an oxalic acid conjugated with the carbo- 

 hydrogen C 6 H 7 ~C 6 H 7 .C 2 O 3 .HO. 



Combinations. The alkaline butyrates are deliquescent, and not 

 crystallisable ; the compounds of butyric acid with the metallic 

 oxides lose a portion of their acid when heated, and even at an 

 ordinary temperature evolve a strong odour. 



Butyrate of baryta, BaO. Bu-f4HO, crystallises in smooth 

 prisms, grouped together in a wart-like form, and having a fatty 

 glistening appearance ; it retains its water of crystallisation at 100, 

 and dissolves readily in water ; if thrown in small pieces on water, 

 it assumes, like camphor, a rotatory motion till it is dissolved.; 

 further, it turns red litmus blue. 



Butyrate of lime, CaO. Bu + HO, crystallises in fine needles; it 

 has the odour of butyric acid, dissolves readily in cold water, but 

 separates almost entirely on boiling, and on dry distillation yields 

 bodies similar to ethereal oils, namely, butyrone, C 7 H 7 O, and 

 butyral, C 8 H 8 O 2 . 



Butyrate of magnesia, MgO.Bu + 5HO, forms white plates 

 resembling boracic acid. 



Butyrate of zinc decomposes on boiling into a strongly basic 

 insoluble salt. 



Butyrate of copper, CuO.Bu-H2HO, occurs in eight-sided, 

 bluish-green prisms, has a strong odour of butyric acid, and is only 

 slightly soluble in water. At a temperature of about 100 most of 

 the acid is expelled from this salt. 



Butyrate of lead does not crystallise, and is only to be obtained 

 in a syrupy form. 



Butyrate of silver forms white nacreous plates, is almost inso- 

 luble, and smoulders at a glow-heat without explosion. 



