i8o Proceedings Columbia Biochemical Association [Sept. 



discover, if possible, a more effective alkali for the biuret reagent 

 than the Standard sodium hydroxid — or a combination of alkalies 

 that might be better. 



Fairly strong Solutions o£ the following alkalies, when substi- 

 tuted for sodium hydroxid in the biuret reagent,^^ yield Solutions that 

 give the biuret test when they are added to dilute Solutions of 

 Witte peptone : potassium hydroxid, ammonium hydroxid, calcium 

 hydroxid, sodium carbonate, conin, piperidin, ethylene di-amin, tri- 

 methyl amin, piperazin, and tetra-ethyl ammonium hydroxid. 



Sodium hydroxid, potassium hydroxid, ammonium hydroxid, tri- 

 methyl amin, and tetra-ethyl ammonium hydroxid are excellent as 

 alkalies in the biuret reagent. Tri-methyl amin appears to be more 

 effective than sodium hydroxid. Tetra-ethyl ammonium hydroxid 

 is seemingly as effective as sodium hydroxid when the reagent is 

 fresh, but the efficiency of the Solution decreases on standing. 

 Piperazin and tetra-ethyl ammonium hydroxid give most satisfac- 

 tory tests when an excess of copper is present. There is apparently 

 an Optimum amount of copper (sulfate) for each alkali. The study 

 is in progress. 



33. A chemical study of salivary mucin. Alfred P. Loth- 

 ROP, Salivary mucin from the submaxillary glands of oxen.was 

 prepared by the Hammarsten-Levene method. It is a white powder, 

 insoluble in water, acid in reaction and readily soluble in dilute 

 alkalin Solutions. 



The sodium salt can be prepared by dissolving mucin in nine 

 parts of 0.5 per cent. sodium bicarbonate Solution plus one part of 

 0.5 per cent. sodium carbonate Solution. The thick Solution is then 

 dialysed until it no longer reacts alkalin to phenolthalein but is still 

 alkalin to litmus. (Prolonged dialysis completely hydrolyses the 

 salt and precipitates the mucin. ) The dialysed Solution may be pre- 

 cipitated by the addition of about six volumes of alcohol, although 

 electrolyte (NaCl) must be present for complete flocculation. The 

 product, washed with alcohol and ether, dries to a fine powder. 



^ Gies : Proceedings of the American Society of Biological Chemists, 1910, 

 i. P- ^7Z'> Journal of Biological Chemistry, 1910, vii, p. Ix. Also, Kantor and 

 Gies : Biochemical Bulletin, 1912, i, p. 264. 



