THE SYNTHESIS OF PROTEIDS. 151 



duct soluble in water, but was precipitated as a curdy mass on 

 the addition of alcohol. Aqueous solutions of this product 

 are precipitable by most of the other precipitants of proteids, 

 namely, tannin, picric acid, mercuric chloride, Millon's re- 

 agent, potassium diiodide, mercuric potassium iodide, phos- 

 photungstic acid in presence of hydrochloric acid, phos- 

 phomolybdic acid, and lead acetate and basic lead acetate. 

 Potassium ferrocyanide, however, gives no precipitate in 

 presence of acetic acid. With caustic potash and copper 

 sulphate a rose-red coloration is formed. Heated with 

 nitric acid the product becomes orange on adding ammonia, 

 and when heated decomposes suddenly leaving a bulky 

 mass of carbon. Its behaviour in this respect is similar to 

 that of gelatin. When heated on platinum, the compound 

 carbonises and swells up, giving the characteristic odour 

 of burning - nitrogenous animal matter. 



We thus see that although Schiitzenberger succeeded in 

 obtaining a substance very like albumin, yet the experiments 

 are hardly .conclusive because some of the characteristic 

 properties of albumin are wanting, and the colour tests for 

 proteid are given by many of the decomposition products 

 of albuminous matter. His partial success will, however, 

 point the way for future attempts, and so far as it goes is in 

 favour of his theory of proteid constitution. 



Some years previous to this, Grimaux (2) obtained by 

 somewhat simpler processes substances which even more 

 resembled proteids than Schiitzenberger's. He was espe- 

 cially interested in colloidal substances, inorganic and 

 organic, but the three that he made which bear on the 

 present question were the following : — 



(A) Colloi'de amidobenzoique. This is made by heating 

 to 1 2 5 C. meta-amidobenzoic acid in sealed tubes with one 

 and a half times its weight of phosphorus pentachloride 

 for ninety minutes. The product, which is a white, friable 

 powder, is washed repeatedly with boiling water to remove 

 all phosphoric acid. The remaining substance is supposed 

 by Grimaux to be an intramolecular anhydride formed by 

 the union of several molecules of meta-amidobenzoic acid 

 with the elimination of water. When ammonia is added it 



