1912] "Alfred P. Lothrop 179 



stance must be present. The urines of man and dog contain col- 

 loidal nitrogenous material.^* It was thought probable that such 

 material is present in all the secretions. 



After a careful process, including the removal of protein without 

 hydrolysis, substance was obtained f rom milk which is white, amor- 

 phoiis, odorless and tasteless; insoluble in the lipin solvents, but 

 forms in water an opalescent Solution which falls to flocculate on 

 boiling. This material does not respond to any of the protein 

 "color tests." It contained about 5.3 per cent. nitrogen; also car- 

 bon, hydrogen, oxygen, and sulfur, but no loosely combined am- 

 monia radicals. 



31. A biochemical test for free acid, with a review of the 

 methods for estimating the various factors in gastric acidity.^^ 

 John L. Kantor. The author presented details along the lines of 

 our original publication on this subject.^^ The test is a microscopic 

 one and depends upon the immediate expansion of moist collagen 

 fibrils when they are immersed in aqueous Solutions containing free 

 organic or mineral acids of the kinds that ordinarily appear in gas- 

 tric Contents. " Combined " acid^^ and acid salts fail to induce such 

 effects. The test may be satisfactorily conducted with a drop of 

 liquid and a single collagen fibril. 



Comparative observations indicate that for free mineral acid 

 (HCl) the collagen-fibril test is equal in delicacy to the Töpfer and 

 Günzberg tests, but that for free organic acid (lactic), or for mix- 

 tures of free mineral and organic acids, it is more delicate than the 

 latter tests. Comparative studies of common factors of interfer- 

 ence with the several tests indicate that the collagen-fibril test ex- 

 hibits the greater delicacy. The color of the Solution under exam- 

 ination had no effect on the test. Further details from the clinical 

 Standpoint, and an abstract of the historical discussion, will be pub- 

 lished at an early date. 



32. A study of modifications of the biuret reagent. Mar- 

 GUERiTE T. Lee. This investigation was made in the endeavor to 



^ Kahn and Rosenbloom : Biochemical Bulletin, 1912, ii, p. 87. 



^ Kantor : Dissertation, Columbia University, 1912. 



^ Kantor and Gies : Proceedings of the American Society of Biological 

 Chemists, 1911, ii, p. 20; Journal of Biological Chemistry, 1911, ix, p. xxvi. 



" Goodridge and Gies : Proceedings of the Society for Experimental Biology 

 and Mediane, 1911, viii, p. 107. 



