CHEMICAL BASIS OF THE ANIMAL BODY. 85 



hours with 1 p.c. caustic potash at 100C and subsequently with water. 

 This process is then repeated with 10 p.c. acetic acid. Finally it is 

 treated for 24 hours in the cold with 5 p.c. hydrochloric acid, washed 

 with water, boiled with 95 p.c. alcohol and extracted for at least two 

 weeks with ether to remove every trace of adherent fat. By the above 

 method it may be obtained as a pale yellowish powder in which the 

 shape of fragments of the original elastic fibres may be still distinguished 

 under the microscope. When moist it is yellow and elastic, but on drying 

 it becomes brittle and may with difficulty be pulverised in a mortar. 

 Sulphur probably does not enter into its composition (?). It may be 

 dissolved by strong alkalis at 100C, and it also goes into solution when 

 treated with mineral acids at the same temperature ; but in the latter 

 case the solution involves decomposition with the formation of much 

 leucin (30 40 p.c.) and traces (-25 p.c.) of tyrosin when the acid 

 employed is sulphuric 1 . If strong hydrochloric acid be employed with 

 chloride of zinc the same crystalline products are obtained together 

 with ammonia, glycocoll, and an amidovalerianic acid, but no glutamic 

 or aspartic acids 2 . In this respect it differs from both ordinary 

 proteids and gelatin, since the former when similarly treated yield the 

 glutamic and aspartic acids but no glycocoll, and the latter never yields 

 the least trace of tyrosin. During the putrefactive decomposition of 

 elastin products similar to the above are obtained together with some 

 peptone-like substance 3 . When treated with superheated water, or 

 with dilute hydrochloric acid at 100 C. or with pepsin or trypsin in 

 acid and alkaline medium respectively, elastin is more or less rapidly 

 dissolved and undergoes a true digestive change, during which products 

 are formed, many of whose general reactions are analogous to those of 

 the digestive products of proteids 4 . It is however as yet uncertain 

 whether a true elastinpeptone can be obtained ; it is more probable 

 that during the digestion only some of the primary substances 

 (elastoses) make their appearance, since they are completely precipi- 

 tated by saturation with neutral ammonium sulphate 5 . Elastin is also 

 rapidly corroded and dissolved by the action of papai'n. (Gamgee.) 



Hilger 6 has obtained a somewhat similar substance from the shell 

 and yolk of certain snakes' eggs. 



1 Erlenmeyer u. Schoffer, Jn. f. p'rakt. Chem. Bd. LXXX. (1860), S. 357. 



2 Horbaczewski, Monatshefte f. Chem. Bd. vi. (1885), S. 639. 



3 Walchli, Jn. f. prakt. Chem. (N.F.), Bd. xvn. (1878), S. 71. 



4 Horbaczewski, loc. cit. 



5 Chittenden and Hart, loc. cit. 



6 Ber. cl. deutsch. chem. Gesell. 1873, S. 166. See also Krukenberg, VergL- 

 physiol. Stud. n. B. 1. Abth. S. 68. 



