ITS CHEMICAL RELATIONS. 51 



According to the investigations of Bonders and Mulder, elastic 

 fibre is entirely insoluble in cold concentrated acetic acid. It is 

 only after continuous boiling for some days in this acid that it gra- 

 dually dissolves. 



' When heated with moderately diluted hydrochloric acid, it dis- 

 solves with a brown colour ; the dissolved substance is soluble in 

 water and in alcohol. 



Xanthoproteic acid is formed by the action of nitric acid. 



According to Zollikofer,* when pure elastic fibre is digested in 

 sulphuric acid, diluted with 1 times its weight of water, it yields 

 leucine only, and no glycine. 



[We may here remark, that Zollikofer recommends the follow- 

 ing as the best method of preparing leucine. Take elastic tissue, 

 (for instance, the ligamentum nuchae of the ox,) purify it by extrac- 

 tion with boiling acetic acid and with water, and afterwards boil it 

 for forty-eight hours with sulphuric acid of the above-mentioned 

 strength, then neutralize with milk of lime, boil the pulpy mass 

 that is now formed, and filter* During the evaporation of the 

 filtered fluid on the sand-bath, the lime-salts that become deposited 

 must be as far as possible removed. On further evaporation in the 

 water- bath, the fluid readily yields crystals of leucine. No glycine 

 (as is remarked above) is formed, and the leucine may be purified 

 without animal charcoal by mere recrystallization in spirit and 

 alcohol. G. E. D.] 



Elastic tissue remains unchanged for a long time, at an ordinary 

 temperature, in a moderately concentrated solution of potash, and 

 it is only after it has been heated for some days that it becomes 

 converted into a gelatinous mass. 



Pure elastic fibre cannot be obtained by mechanical means, but 

 must be procured, as we have already observed, by removing the 

 fibrillee of cellular tissue and the fibre-cells by boiling with acetic 

 acid, and then adding a dilute solution of potash. 



Tilanus found in the elastic substance of the ligamentum 

 nuchse, after it had been purified in the above-described manner, 

 55'75-g- of carbon, 7*41$ of hydrogen, and l7'74$ of nitrogen. 

 We do not think that any reliable formula can be obtained from 

 this analysis, even by the help of the analysis of the chlorine- 

 compound. 



Dondersf has recently come to the view, that all cell-mem- 

 branes consist of a substance identical with, or at all events, very 



* Ann. der Ch. u. Pharm. Bd. 82, S. 168-180. 

 t Zeitsch. f. wiss. Zool. Bd. 3, S. 348-358, and Bd. 4, S. 242-251. 



E 2 



