242 IMPORTANCE TO TOXIGOLOaiST. 



upper portion of the small intestine. There are many indol-forming 

 bacteria, and while some of these may be present in any tissue, they 

 are certainly present in health and in disease, during life and after 

 death, in the small intestine. 



Indol and its derivatives are products of anaerobic putrefaction and 

 this accounts for the fact that the reactions obtained in the above- 

 mentioned experiments are not familiar to those toxicologists who 

 have employed tissue allowed to putrefy in the presence of oxygen. 

 It should be remembered that indol may be prepared synthetically 

 and it may be obtained from putrefying tissue. Samples obtained 

 from the two sources do not always give exactly the same reactions. 

 Skatol is another product of anaerobic putrefaction which may inter- 

 fere with the tests for morphin. While it would be comparatively 

 easy to distinguish pure morphin from either indol or skatol, the 

 results of the above-mentioned experiments show that the separation 

 of morphin from tissue, decomposing in the absence of oxygen, and 

 its identification are, by the methods now generally employed, so 

 uncertain that the conscientious chemist will seek for methods free 

 from these sources of error before he gives positive testimony of the 

 presence of this alkaloid. We have spoken of indol and its deriva- 

 tives as being present in decomposing tissue, and it should be stated 

 that the number of known indol derivatives is by no means small, 

 and how many others there may be which remain unknown no one 

 can tell. Many of these substances give brilliant color reactions. 

 Indoxyl is an easily decomposable substance, which gives some 

 striking color reactions, among which may be mentioned the produc- 

 tion of indigo blue with ferric chlorid in the presence of free hydro- 

 chloric acid. 



Skatol-carbonic acid is another product of putrefaction and E. and 

 H. Salkowski obtained 1.3 grams from 2 kg. of moist fibrin after 

 twenty-six days' putrefaction. Among the known color reactions of 

 this substance Hoppe-Seyler mentions the following : 



1. If a dilute solution of this acid (1:1000) be treated with a few 

 drops of pure hydrochloric acid of 1.2 specific gravity, and then with 

 a few drops of potassium nitrate solution (2 per cent.), a cherry-red 

 coloration is produced, and later a red precipitate falls. 



2. If such a solution be mixed with an equal volume of hydro- 

 chloric acid, and then a few drops of chlorid of lime solution (J per 

 cent.) be added, a purple-red color is produced. 



3. Treated with a few drops of hydrochloric acid, then with two 

 or three drops of a very dilute solution of ferric chlorid and heated, 

 the mixture becomes intensely violet before boiling. Skatol-carbonic 

 acid is non-volatile. 



Skatol-acetic acid has been obtained by Nencki by the anaerobic 

 putrefaction of serum albumin. The aqueous solutions of this sub- 

 stance give with ferric chlorid a white cloudiness, which on warm- 



