474 ^ APPENDIX. 



arrived at the conclusion that as heematoYdin is always formed 

 when blood in a stagnating state occurs in the body, so this sub- 

 stance, bilifulvin, is produced wherever bile stagnates. 



(33) Addition to p. 330, line 26. Dana* has recommended a 

 very good method of detecting the presence of sulphur in organic 

 matters containing that substance in not very minute quantity. 

 We make a mixture of carbonate of soda, starch, arid the substance 

 to be tested for sulphur, and heat it by the blow-pipe on a platinum 

 support ; we then place the fused mass in a watch-glass with a 

 drop of water, and add a small crystal of the nitroprusside of sodium 

 discovered by Playfair ;f if sulphur be present, that is to say^ if 

 sulphide of sodium be formed, the fluid will assume a splendid 

 purple colour; most commonly a red tint first appears, which, 

 assuming a shade of blue, becomes purple, and finally passes into 

 a very deep azure blue, but even this is not persistent, for the fluid 

 at last entirely loses all its colour. 



Since the termination of Mulder's investigations on the protein- 

 substances, several other views regarding the constitution of complex 

 organic bodies have been promulgated. We have to a certain extent 

 given up the older theory of organic radicals (on which Mulder's view 

 is based), and have turned our views towards the establishment of 

 conjugated compounds, salt-like combinations, and the like. The 

 unexpected discoveries of the resolution (or cleavage) into other 

 substances of amygdalin (Liebig and Wohler), asparagin, salicin, and 

 populin (Piria), the discoveries of the ammonia-alkaloids (Wurtz), 

 and their theoretical constitution (Hoffmann and Kolbe),and finally, 

 the observation that many nitrogenous bodies, when decomposed in 

 various ways, yield special volatile alkaloids (Anderson, Rochleder, 

 Wertheim, and others) give a certain support to the view that the 

 protein-substances may have a constitution analogous to that of 

 these complex bodies, and that there may be contained in them 

 several proximate constituents conjugated together, or combined 

 in the manner of salts. Thus, for instance, WurtzJ obtained 

 methylamine from casein by treating it with alkalies, and Roch- 

 leder by decomposing it with chlorine, and the latter chemist 

 consequently regards methylamine as one of the proximate con- 

 stituents of casein. This view seems to gain support from the 

 remarkable circumstance that there is an albuminous substance in 



* Chemical Gazette. 1851. p. 459. 



t Philosophical Magazine. 3Ser. Vol. 36, pp. 197-221, 271-284, and 348-360. 



t Compt. rend. T. 30, p. 9. 



Ann. d. Ch. u. Fharm. Bd. 73, S. 56. 



