536 APPENDIX. 



any trace of it in the sweat either of puerperal women or of per- 

 sons suffering from gout or rheumatism, and it was unquestionably 

 proved that this acid was not present in the sweat collected by 

 Schottin. Favre, who seems to have entirely overlooked the 

 presence of volatile acids in the sweat, maintains, however, that he 

 has not only demonstrated the existence of this acid by the exhi- 

 bition of its zinc-salt and elementary analysis, but that he has 

 determined the actual quantity of the lactate of potash and soda in 

 the sweat at 0'03l7. 



Favre further believes that he has discovered a new nitro- 

 genous acid in the sweat, to which he has given the name of 

 hydrotic or sudoric acid. From two elementary analyses of its 

 silver-salt he assigns to it the formula C 10 H 8 NO 13 . 



With regard to the presence of urea in the sweat, Favre 

 regards it as a normal constituent, and he thinks that it is upon 

 its presence or that of a similar substance that the readiness with 

 which the fluid becomes alkaline depends; but notwithstanding 

 the most careful search, Schottin failed in detecting it, either in 

 the normal sweat generally, or in the sweat of the feet which so 

 soon becomes alkaline. Schottin, however, made the interesting 

 observation (see foot-note to vol. ii, p. 388) that in ur&mia 

 (especially when occurring in cases of cholera) considerable quan- 

 tities of urea pass into the sweat. 



We sometimes find the bodies of persons who have died from 

 cholera coated with a thin bluish layer, which on closer examina- 

 tion is found to consist of a fine powder, composed, for the most 

 part, of urea. 



Lehmann was unable to detect any trace of sugar in the sweat 

 of a diabetic patient, who, contrary to the general rule, perspired 

 very copiously in a hot summer. 



Schottin has instituted several very admirable experiments on 

 the passage of several matters into the sweat, and from these it 

 would appear that benzole acid, and also succinic and tartaric 

 acids, pass very rapidly and unchanged into the sweat. Iodide of 

 potassium was not detected in the sweat until it had been taken 

 for five days (half a drachm daily). When salicin was taken, 

 neither this substance itself nor any of its known products of 

 decomposition, could be detected in the sweat. Quinine, taken to 

 the amount of 12 grammes, did not pass into the sweat. After 

 the ingestion of much sugar of milk., neither a saccharine matter 

 nor lactic acid appeared in the sweat. 



It would be very interesting to decide, whether the benzoic 



