ANALYTICAL EVIDENCE. 303 



The composition of the membrane lining the interior of 

 the shell of the egg, approaches closely to that of horn. 

 According to Scherer, it contains 



Scherer.* a 



Carbon . . . .' . . . 50-674 



Hydrogen ...... 6-608 



Nitrogen ...... 16761 



25-957 



Sulphur 



a Ann. der Chem. und Pharm., XL., 60. 



The composition of feathers is also nearly the same as 

 that of horn. 



Scherer.* a 



The analysis here given of the beard of feathers agrees 

 closely with that of horn, while that of the quill is more 

 accurately represented by the attached formula, which 

 differs from that of horn by 1 eq. of oxygen only. 

 a Ann. der Chem. und Pharm., XL., 61. 



7. COMPOSITION OF THE PIGMENTUM NIGRUM OCULI. 



Scherer.* a 



Carbon . . . 58-273 58-672 57-908 

 Hydrogen . . 5-973 5-962 5-817 

 Nitrogen . . 13-768 13-768 13-768 

 Oxygen . . 21-986 21-598 22-507 

 a Ann. der Chem. und Pharm., XL., 63. 



