80 THE PROTEIN SUBSTANCES. 



bacterial proteids, 1 are free from sulphur; some, such as gelatin and 

 elastin, are very poor in sulphur, while others, especially horn sub- 

 stances, are relatively rich in sulphur. On hydrolytic cleavage with 

 mineral acids, the sulphur of the protein substances is regularly, at 

 least in part, split off as cystine (K. MORNER) or, with bodies poorer in 

 sulphur, as cysteine (EMBDEN), but this, according to MORNER and PATTEN, 

 is a secondary formation. From certain protein substances a-thiolactic 

 acid (SUTER, FRIEDMANN, FRANKEL), which MORNER claims is also pro- 

 duced secondarily, mercaptans and sulphureted hydrogen (SIEBER and 

 SCHOUBENKO, RUBNER), and a body having the odor of ethyl sulphide 

 (DRECHSEL) have been obtained. 2 



A part of the sulphur separates as potassium or sodium sulphide on 

 boiling with caustic potash or soda, and may be detected by lead acetate 

 and quantitatively determined (FLEITMANN, DANILEWSKY, KRUGER, 

 FR. SCHULZ, OSBORNE, K. MoRNER 3 ). What remains can be detected 

 only after fusing with potassium nitrate and sodium carbonate and 

 testing for sulphates. The ratio between the sulphur split off by alkali 

 and that not split off is different in various proteins. No conclusions 

 can be drawn from this in regard to the number of forms of combination 

 which the sulphur has in the protein molecule. As shown by K. MORNER, 

 only about three-fourths of the sulphur in cystine can be split off by 

 alkali, and the same is true for the cystine-yielding complex of the pro- 

 tein substances. If the quantity of lead-blackening sulphur in a pro- 

 tein body be multiplied by f, we obtain the quantity corresponding to 

 the cystine sulphur in the body. By such calculation MORNER found 

 in certain bodies, such as horn substance, seralbumin and serglobulin, 

 that the quantity of cystine sulphur and total sulphur were identical, 

 and therefore we have no reason for considering the sulphur in these 

 bodies as existing in more than one form of combination. In other 

 proteins, such as fibrinogen and ovalbumin, on the contrary, only one- 

 half or one-third of the sulphur appeared as cystine sulphur. 



Just as in the products of acid hydrolysis of proteins we know of 

 two forms of oxygen bondage, the hydroxyl form OH and the carbonyl 



1 See Nencki and Schaffer, Journ. f . prakt. Chem. (N. F.), 20, and M. Nencki, Ber. 

 d. d. chem. Gesellsch., 17. 



2 K. Morner, Zeitschr. f. physiol. Chem., 28, 34, and 42; Patten, ibid., 39; Embden, 

 ibid., 32; Suter, ibid., 20; Friedmann, Hofmeister's Beitrage, 3; Sieber and Schou- 

 benko, Archiv d. sciences biol. de St. Petersbourg, 1; Rubner, Arch. f. Hygiene, 19; 

 Drechsel, Centralbl. f. Physiol., 10, 529; Frankel, Sitzungsber. d. Wien. Akad., 112, 

 TI b, 1903. 



3 Fleitmann, Annal. der Chem. und Pharm., 66; Danilewsky, Zeitschr. f. physiol. 

 Chem., 7; Kriiger's, Pfluger's Archiv, 43; F. Schulz, Zeitschr. f. physiol. Chem., 25; 

 Osborne, Connecticut Agric. Expt. Station Report 1900; Morner, 1. c. 



