in ON THE SYNTHESIS OF ALBUMINS 117 



The substance which Schwarzschild examined must have been a 

 mixture of the biuret-base and glycocoll-anhydride, for these two 

 combine, according to Curtius, to form definite chemical compounds. 



The drier the glycocoll-ester the greater is the yield of the biuret- 

 base, and inversely the less the formation of glycin-anhydride. Levy 

 working in Curtius's laboratory found that glycocoll-ester mixed with 

 one third of absolute ether is converted, in the course of a few weeks, 

 into the biuret-base to the extent of 99 per cent. 



Gumlich has prepared an anhydride of the triglycylglycinester 

 or biuret-base, 1 as has also E. Fischer. 2 



The biuret-base is readily soluble in warm water ; gives a strongly 

 alkaline reaction, and is slightly soluble in hot chloroform and 

 acetic ester. When boiled with water it becomes converted into a 

 gelatinous substance. It attracts the CO 2 of the air and in 10 

 per cent watery solutions gives the following reactions common to 

 albuminous substances : 



1. With caustic potash and copper sulphate the biuret 



reaction. 



2. Ferric chloride gives a brownish red precipitate, soluble 



in an excess of the reagent and in much water. 



3. Copper sulphate and acetate cause after a short time a 



turbidity and then a blue precipitate, very slightly 

 soluble in excess of the reagents. 



4. Mercuric chloride causes a precipitate which, at first, 



dissolves again, but then ultimately becomes permanent. 



5. Lead acetate gives an immediate white precipitate insoluble 



in excess and on dilution. 



6. Strong HC1 and H 2 S0 4 dissolve the base without altering 



it ; strong HN0 3 decomposes the substance after a short 

 time, gas being given off under a violent reaction. 

 7,'Phosphomolybdic acid forms a yellow precipitate, soluble 

 on heating and in much water. 



8. Tannic acid gives at once a brown precipitate insoluble in 



excess and on dilution. 



9. Picric acid throws down from saturated solutions of the 



base or its hydrochloride a precipitate which is fairly 

 soluble in water and less soluble in alcohol. 



lodine-potassium-iodide produces in a short time a brown pre- 

 cipitate; mercury-potassium-iodide a white precipitate; bismuth- 

 potassium-iodide a yellow precipitate soluble in much water. Ferro- 



1 Gumlich, Ber. d. deutsch. chem. Ges. 37. 1300 (1904). 

 2 E. Fisher, ibid. p. 2501. 



