AGEICULTUEAL CHEMISTRY^ AGROTECHNY. 703 



"A little over 12 per cent of the weight of the invertase is still unaccounted 

 for, though a part of this may be water. Until this is accounted for, and until 

 the parallelism between nitrogen content and activity be found to be more 

 exact the foregoing conclusion that the ferment is a protein must be tentative. 

 Further work on the subject is in progress." 



Influence of temperature upon the activity of cellase, G. Bektrand and 

 A. CoMPTON (.Bui. Soc. Chim. France, //. ser., 9 (1911), No. 2, pp. 100-103, 

 fig. 1). — The optimum temperature of the cellase obtained from sweet almonds 

 was found in the region of 46° C. The action of this enzym is absolutely de- 

 stroyed at 75° and under certain circumstances this occurs at 60°. 



Methods of volumetric analysis, H. Beckubts {Die Methoden der Mas- 

 sanalyse. Brunswick, 1910, vol. 1, pp. YII-\-Ii82, figs. 87).— This is virtually a 

 completely .revised edition of Mohr's Lehrbuch der Chemisch-Analytischen 

 Titriermethode, with many important additions. 



A study of melting point determinations, G. A. Menge {Puh. Health and 

 Mar. Uosp. Serv. U. S., Hyy. Lab. Bui. 70, pp. 101, figs. 21).— After considering 

 the numerous existing methods for determining the melting point the author 

 describes a method, devised by the division of pharmacology of the U. S. Public 

 Health and Marine Hospital Service, for the puriwse of recommending it to the 

 committee of revision of the U. S. Pharmacopoeia for adoption as official in 

 standardizing drugs. 



An improvement of the Folin method for the determination of urinary 

 ammonia nitrogen, M. Steel (Jour. Biol. Cliem., 8 (1910), No. 5, pp. 365- 

 379). — After discussing the various methods, the results obtained with them, 

 and the sources of error, the author presents his modification of the Folin 

 method," so that it can be made to liberate all the ammonia from ammonium 

 magnesium phosphate and at the same time be applied to urinary analysis. 

 This is accomplished by the addition of sodium hydrate instead of sodium car- 

 bonate and the addition of sodium chlorid. Ordinary organic constituents of 

 urine are not decomposed by the amount recommended. See also a note by 

 Kober (E. S. R., 23, p. 416). 



Note on the determination of ammonia in urine, O. Folin (Jour. Biol. 

 Chem., S (1910), No. 6, pp. .'i97, 498).— The correctness of Steel's method (see 

 above) is pointed out, but in view of the fact that the amount of ammonium 

 magnesium phosphate is usually very small in urines, since these are often de- 

 composed or alkaline, the author believes it hardly necessary to substitute 

 sodium hydrate and sodium chlorid for sodium carbonate and sodium chlorid. 



About the estimation of phosphates, Crispo (Ahs. in CJicm. Ztrj., 3-) (1910), 

 No. 80, p. 7i7).— It is concluded that Pemberton's method (B. S. R., 20, p. 703) 

 gives the best results and in the shortest time. 



Improvements in the Knorr fat extraction apparatus, H. L. Walter and 

 C. E. Goodrich (U. S. Dept. Agr., Bur. Chem. Circ. 69, pp. k, fios. 4).— One of 

 the modifications proposed consists of making two perforations in the neck of 

 the flask for the purpose of eliminating certain difficulties in manipulation 

 which often present themselves with the old flask. The others consist of a 

 metal spring, which is placed in the extraction tube to hold the material being 

 extracted in place during the process, and a new form of metal disk. With 

 these modifications applied it is possible to return to the use of a cheaper and 

 simpler form of extraction tube. 



A method for the determination of sodium icdid in animal tissues, P. J. 

 Hanzlik (Jour. Biol. Chem., 7 (1910), No. 6, pp. 459-46Jt; abs. in ZentM. 



"Ztschr. Physiol. Chem., 37 (1902), p. 161; Amer. Jour. Physiol., 8 (1902-3), 

 p. 330. 



