230 



sical researclies of Dr. Schunck, and furtber researches are neces- 

 sary to clear iip the nature of the substance which yields in the 

 présence of isatin isatocyanin. as well as to establish definitely Bei- 

 jerinck's contention, that Isatis tinctoria does contain Iree indoxyl. 

 Schunck ') pointed out, that in case Beijerinck's views were correct 

 an extract of the leave of the plant ought to yield indigotin on pas- 

 sing air through it, as a matter of fnct he could notice no forma- 

 tion of the colour. Against Beijerinck's contention niay be put still 

 another objection: that it is not impossible, that isatin dissolved in 

 boiling water partly fonns isatic acid, the hydrogen ions of which 

 may cause hydrolytic action. One thing however to my mind has 

 been proved by the experiment of Beijerinck. namely that the indi- 

 goproducing substances présent in Isatis on the one hand and in 

 Indigofera and Polygonum tinct. on the other are not identical, 

 although indoxyl is the intermediate product in ail cases. 



28. M. L. BIEK et .\1. L. M.iRCHLEWSKl m. c. Absorbcya ultrafioleto- 

 wych promieni przez barwiki iôic'i, urobilin^ i proteinochrom. (Ab- 

 soriJtion of ulti-a - violet rn>/a by hilirubiii, hiliverdin, tirobilin 

 and pi'oteincliroin ). (L'absorption des rai/oiis nltraniolets par les ma- 

 tières colorantes de la bile, l'urobiline et le protéinochrome ). 



It is well known that the colouring matter of the blood and 

 its derivatives, as well as Chlorophyll and its derivatives, cause in the 

 ultraviolet part of the spectrum very charaeteristic absorption bands. 

 According to Hartley -) and bis co-workers the absorption of ultra- 

 violet rays is a preeminently constitutional property of substances» 

 and it might therefore hâve been expected that in the face of the 

 proved ^) convertibility of haematogenic urobilin, which is undoub- 

 tedly closely related to the hepatic urobilin, — the colouring mat- 



') 1. c. 



2) Proc. Eoyal Society 2«, 233, 29, 290. l'hil. Trans, 170, 257. Proc. Royal 

 Society 31, 1. Journal chem. .Society. 47, 685. Ber. d. deut-sch. chem. Gesellsch. 

 18,592, .lourn. cliem. Society, 50. 58, Journ. chem. .Society, .53, 6-il. Her. der deutüch. 

 chem. Gesellsch. 21, 689. etc. 



') Bulletin International de l'Acidémie des Sciences de Cracovie. Classe 

 des Sciences mathématiques et naturelles 1901. p. 277. 



