(INIMICAL UASIS <>r THK ANIMAL K<>I>Y. I'.i? 



be distinguished from hydrochinon by yielding a precipitate \vitli 

 normal acetate ill lead which is Soluble in acetic acid, whereas the 

 latt' T substance does not No simple directions can be given for 

 the separation and estimation of pyrocatechin in presence of 

 phenol, kivsnl, and hydrochinon. 1 



Hut little is known as to the source of this substance in urine 

 apart t'r>m its probable formation from the phenol produced by 

 putrefactive changes in tin- alimentary canal. In herbivora there 

 is some evidence that it is derived from certain aromatic consti- 

 tuents of their food.- 



8. Hydrochinon. CH 4 (OH) 2 . Pared i o. xy he nxol. 



II kfl not yet been described as occurring normally in urine, but 

 only as the result of the invest ion of phenol. It exists in urine 

 as an ethereal compound with sulphuric acid, and is largely tin- 

 cause of the dark colour which this excretion assumes after tin- 

 absorption of phenol on exposure to the air. It resembles pvr<>- 

 cati-chin in effecting the reduction of metallic salts, but differs 

 from it in being nearly insoluble in cold benzol and in not yield- 

 ing any precipitate with normal lead acetate. This latter property 

 sutlices for its separation from pyroeatechin. It is readily con- 

 verted by oxidation into chinon C,,Hi ( } -- whose characteristic odour 

 affords a further means of identification, ami when heated in an 

 open test-tube it yields a blue sublimate. 3 



The third known isomeric dioxyben/ol. vix. meta-dioxybeii/ol 

 sore-in, has not yet been found in the animal body or in 

 urine. 



Tin: IM>K;O SKIMKS. 

 ' 



1. Indol. (Ml N 



Indol oeniix <-haracteri<tically in the f;eces. to which with 



skatol it impait> their ]eculiai Iv unplea-ant odour. 1 It- pi- 



In-ie is due to its formation during tin- putrefactive decomposition 



of proteid^ which u-ually iccur> t' extent in the 



alimentary canal, part of the ind<>l leaving the body in the urine 



:im -alt of indoxyl-iilpliurie ''"/''), the 



mder bi-ing excreted with the f.i-ce<. It may readily be 



obtained, contaminated b\ varying' '|iiantities of phenol and 



/: /,/, v .<,V r/,,,,,. H,| M <i --:.' i, 8. 188. Schmiedeberg, Joe. 



. - 



,,/n/.W. 'V(.i. Mil n (1*7*1. Si. 



t,. the 1;' .ni:lv i|""'' nlarly 



I'.Miiinann 11 I'rm--.- .I"/. /I fifn/^ol. ./<//. ^iippv- 



M.UIII II. 1 ' 



l!:niii,:n.n. /' '/. I',. I \ i 



1 l;.|.!/irj.-\\ski. .\rrl, / .|;j,i.' H, /'/,.,,./ I- 



