229 



•Solubility ia 

 wlaeiMl acctic acid 



l n d i r u Vi î ii 



dissolves easily vvitli 

 a iTiaffeiita colour 



1 sa t ocy a n i n. 



easilj with a blue colour, 



whicli disappears oa 



standing. 



absorption spectrum 



solubility in alcohol. 



solubility in coiic 

 suipburic acid. 



a band in tlie green 

 part of tbe spectrum 



a l)and in the yellow part 

 of the spectrum. 



with difficulty giving 

 magenta coloured solution 



with great difficulty 



The blue colour fades away 



quickly 



. ^ , j ,. u 1 "t brst yellowish, the solu- 



at hrst reddish brown. on i ,. , -^ ' ,. 



... » I tion becoines on standing 



heating magenta culour , . " 



" " blue. 



I hiul not enough of isatocyanin to inake a complète analysis, 

 but the appended nitrogen déterminations of two independently pre- 

 pared samples seem to show that the method of purifying mentio- 

 ned above leads to a definite chemical individuum. 



1) 0.1174 gr. gave 9.7 cm^ (t = 14» p = 748 mm) 



eorresponding to 9.56 % N 



2) 0.1100 gr. gave 8.8 cm^^ (t = 12» p = 747 mm) 



eorresponding to 9.32 "/o N. 



As regards the chemical nature of isatocyanin I hâve no sug- 

 gestions to ofFer. I may however mention that it resembles some- 

 what the colouring matter obtained by the action of pyrroline on 

 isatin, and of acetic anhydride on the C(jndensati(in product of pipe- 

 ridine with isatin. The two latter substances are bye the by not iden- 

 tical, as was supposed by Schotten, as may be seen by comparing 

 the absorptions caused by them in the spectrum. The colouring 

 matter obtained from piperidine and isatin causes a band with a ma- 

 ximum intensitv at a 618 — 661. The colouring matter from pyrro- 

 line and isatin causes gênerai absorption of the red but no bands. 

 Isatocyanin causes a band with a maximum intensity on the so- 

 dium line. 



The tacts described above tend to show that the chemical 

 compositions of dried and fresh leaves of Isatis tinctoria vary very 

 considerably. 



That the extracts of dried leaves contairi .a substance which 

 under certain conditions produces indigotin. follows from the clas- 



