386 PHYSIOLOGICAL CHEMISTRY 



acid, and skatoxyl-sulphuric acid. Pyrocatechol-sulphuric acid also 

 occurs in traces in human urine. The total output of ethereal sulphuric 

 acid (as SOs) varies ordinarily from o.i gram to 0.25 gram for 24 hours 

 and comprise 5-15 per cent of the total sulphur. In health the ratio 

 of ethereal sulphuric acid to inorganic sulphuric acid is about i : 10. 

 These ethereal sulphuric acids originate in part from the phenol, cresol, 

 indole and skatole formed in the putrefaction of protein material in 

 the intestine. The phenol passes to the liver where part of it is conju- 

 gated to form phenol potassium sulphate and appears in this form in the 

 urine whereas the indole and skatole undergo a preliminary oxidation to 

 form indoxyl and skatoxyl respectively before their conjugation and 

 elimination. 



It was formerly generally considered that each of the ethereal sul- 

 phuric acids was formed principally in the putrefaction of protein 

 material in the intestine and that therefore a determination of the total 

 ethereal sulphuric acid content of the urine was an index of the extent to 

 which these putrefactive processes were proceeding within the organism. 

 Folin, however, conducted a series of experiments which seemed to 

 show that the ethereal sulphuric acid content of the urine did not afford 

 an index of the extent of intestinal putrefaction, since these bodies 

 arise only in part from putrefactive processes. He claims that the 

 ethereal sulphuric acid excretion represents a form of sulphur metabolism 

 which is more in evidence upon a diet containing a very small amount of 

 protein or upon a diet containing absolutely no protein. The ethereal 

 sulphuric acid content of the urine diminishes as the total sulphur con- 

 tent diminishes but the percentage decrease is much less. Therefore 

 when considered from the standpoint of the total sulphuric acid content 

 the ethereal sulphuric acid content is not diminished but is increased, 

 although the total sulphuric acid content is diminished. Folin's experi- 

 ments also seem to show that the indoxyl sulphuric acid (indoxyl potas- 

 sium sulphate or indican) content of the urine does not originate to any 

 degree from the metabolism of protein material but that it arises in 

 great part from intestinal putrefaction and that the excretion of indoxyl 

 sulphuric acid may alone be taken as a rough index of the extent of putre- 

 factive processes within the intestine. Indoxyl sulphuric acid, 



CH 



/\ 



HC C C(O.S0 3 H), 



HC C CH 



\/\/ 

 CH NH 



