116 THE PROTEIN SUBSTANCES. 



ZOJA found 0.276 per cent sulphur and 16.96 per cent nitrogen in 

 elastin. HEDIN and BERGH found different quantities of nitrogen in 

 aorta-elastin, depending upon whether HORBACZEWSKI'S or SCHWARZ'S 

 method was used in its preparation. In the first case they found 15.44 

 per cent nitrogen and 0.55 per cent sulphur, and in the other 14.67 per 

 cent nitrogen and 0.66 per cent sulphur. RICHARDS and GIBS found 

 0.14 per cent sulphur and 16.87 per cent nitrogen in elastin. 



The quantity of hydrolytic cleavage products are given in the table 

 on page 124. It is sufficient to here call attention to the fact that no 

 aspartic acid and only very little glutamic acid have been found. The 

 hexone bases have been obtained, but only in very small amounts, so 

 that the basic nitrogen represents only 3.34 per cent of the total nitro- 

 gen (RICHARDS and GIES). This fact and the very low sulphur content 

 make it questionable whether the elastin is a unit body. 



Indol and skatol have not been found on the putrefaction of elastin, 1 

 but SCHWARZ. on the contrary, obtained indol, skatol, benzene, and 

 phenols on fusing aorta-elastin with caustic potash. On heating with 

 water in closed vessels, on boiling with dilute acids, or by the action of 

 proteolytic enzymes, the elastin dissolves and splits into two chief prod- 

 ucts, called by HORBACZEWSKI hemielastin and elastinpeptone. Accord- 

 ing to CHITTENDEN and HART, these products correspond to two proteoses 

 designated by them protoelastose and deuteroelastose. The first is soluble 

 in cold water and separates out on heating, and its solution is precipi- 

 tated by mineral acid as well as by acetic acid and potassium ferrocyanide. 

 The aqueous solution of the other does not become cloudy on heating, 

 and is not precipitated by the above-mentioned reagents. According 

 to RICHARDS and GIES, elastoses, especially protoelastoses, and true 

 peptones are formed, the latter only to a slight extent. 



Pure elastin when dry is a yellowish-white powder; in the moist 

 state it appears like yellowish-white threads or membranes. It is insol- 

 uble in water, alcohol, or ether, and shows a resistance toward the action 

 of chemical reagents. It is not dissolved by strong caustic alkalies at 

 the ordinary temperature and only slowly at the boiling temperature. 

 It is very slowly attacked by cold concentrated sulphuric acid, but it 

 is relatively easily dissolved on warming with strong nitric acid. Elastins 

 of different origins act differently with cold concentrated hydrochloric 

 acid; for instance, elastin from the aorta dissolves readily therein, while 

 elastin from the ligamentum nuchse, at least from old animals, dissolves 

 with difficulty. Elastin is more readily dissolved by warm concen- 

 trated hydrochloric acid. It responds to the xanthoproteic reaction 

 and to that with MILLON'S reagent. 



1 See Walchli, Journ. f. priikt. Chem. (N. F.), 17. 



