Colouring-matters of tlw so-called Bile of Invertebrates. SfG. 397 



On adding an acid, such as nitric, in small quantity, two very 

 characteristic bands came into view : — 



X594— 587 -5 (sp. 17) 



2nd „ X556"5— 542 



At first sight they seem to resemble the bands of acid haBmato- 

 porphyrin, but they are different. To prove this I adapted an inter- 

 polation curve to the drawing of the spectrum of that body figured by 

 Hoppe-Seyler and found the following measurements for acid hsemato- 

 porphyrin : — 



1st Band X601— 589 



2nd „ X566— 546 



For his alkaline hsematoporphyrin the following measurements were 

 found : — 



1st Band X630— 615 



2nd „ X601— 565 



3rd „ X551— 539 



4th „ X521— 498 



Hence they are not identical. 



I have also prepared ha3matoporphyrin in different ways, and find 

 that urohsematin, although closely resembling it, is not the same body, 

 nor is it identical with Baumstark's* urorubrohcematin or urofusco- 

 hcematin, as the solubility of these bodies is different. The other 

 characters of the isolated pigment are described in my last paper.f 



Spectroscopic Detection of Indican in Urine. — In cases where Jaffe's 

 test fails to detect indican in urine the spectroscope is able to detect 

 it. X The best method, and one which, after repeated trials, I find easily 

 applied, is somewhat like that of Stockvis, but while he used nitric I 

 use hydrochloric acid. The urine is mixed with about its own bulk of 

 hydrochloric acid and boiled ; after cooling, it is agitated with chloro- 

 form, not violently shaken,and left to rest for some time. When the 

 urine contains indican the chloroform-layer is more or less violet and 

 shows a band before D. The latter corresponds in position with that 

 of the so-called "omicholin." In applying the test the urine always 

 gets more or less red, and there is a strong absorption of the violet 

 end of the spectrum ; now I find that in cases where no indican is 

 present this reddening takes place. Some authorities say that this 

 reddening is due to urrhodin, others that it is due to indigo-red, while 

 others maintain that these two colouring-matters are the same. But 



* " Berichte der Deutsch. Cliem. Gesellsch.," 1874, Bd. 7, p. 1170. 

 f " Proc. Koy. Soc," 1880, vol. 31, p. 206. 



X Jaffe's test is described in most works on the urine. See e.g., Neubauer and 

 Yogel, " Analysis of Urine," American translation, 1879. 



