ON THE COMPOSITION OF BIRD-LIME. 29 



When bird-lime is kept for a long time, a thin brittle skin forms 

 on its surface, which is readily soluble in spirit. This skin consists 

 probably of the resinoïd body. If it docs not, then Ave have no evidence 

 as to whether the resinoïd body is produced during the saponification 

 of the bird-lime, or exists in it ready-formed, as the result of slow 

 atmospheric oxidation. 



In composition the resinoïd body differs from mochylic alcohol 

 only in having two atoms less of hydrogen, as the following analyses 

 and calculation show: — 



I. II. C,oH,,0 



Carbon 83.79 83.66 83.87 



Hydrogen 11.80 11.92 11.83 



Oxygen 4.30 



100.00 



The fatty acids of bird-lime. 



The fatty acids of bird-lime are two, as already stated, palmitic 

 acid, and, in small quantity only, a semi-liquid acid, the calcium salt 

 of which is soluble in spirit and in ether. This acid has not been 

 further examined. The other shows all the characters of palmitic 

 acid. Melting point, 61.5°. Analysis (I.) of acid prepared by 

 saponification, and ( II.) of acid obtained by destructive distillation of 

 purified bird-lime: — • 



I. II. Palmitic acid. 



Carbon 74.98 74.86 75.00 



Hydrogen 12.67 12.55 12.50 



Oxygen 12.50 



100.00 



The potassium salt yielded 13.3 per cent, of potassium. 



