iQis] Th. Lissizin 23 



To 40 c.c. of the filtrate, which was obtained in the oxidation 

 of the hair with 2 percerit potassium permanganate sol. (p. 19) and 

 which contained 0.0022 gm. of sulfur as sulfuric acid, was added 

 0.2300 gm. of cystin (with a sulfur-content of 0.0614 gm.), and 45- 

 50 c.c. of 2 percent permanganate sol. After the reaction was ended, 

 the fluid was filtered, the precipitate washed and the filtrate together 

 with the washings was evaporated to dryness. The residue was 

 acidified with hydrochloric acid, and the precipitate of oxy-proto 

 sulfonic acid separated by filtration. The new filtrate, with the 

 washings, was then precipitated with barium chlorid in the usual 

 way (XIX). 



XIX. From this precipitate 0.2266 gm. of barium sulfate 

 (0.031 1 gm. of sulfur) was obtained. Thus, from the oxidation 

 of cystin I obtained 0.031 1-0.0022, 0.0289 gm. of sulfur, or 46.9 

 percent of the total sulfur, as sulfuric acid. 



From the results of these experiments it follows that a much 

 larger amount of sulfur is split off as sulfuric acid by the oxidation 

 of cystin with permanganate than by the similar oxidation of keratin. 

 It is f urther to be noted that, in the process, some cystin always re- 

 mains unoxidized and that, among the oxidation products of cystin, a 

 small amount of hydrogen sulfid is always present, while in the dis- 

 tillates of the oxidation products of hair, hydrogen sulfid is never 

 found. 



General conclusions. These data suggest the following con- 

 clusions: In the oxidation of keratin the largest part of the con- 

 tained sulfur remains in organic combination, and only one tenth 

 is converted into sulfuric acid. The oxidations of cystin and of 

 keratin proceed along different lines. 



I have undertaken further work on this subject. 



