1919] AGRICULTURAL CHEMISTRY — AGROTECHNY. Ill 



isms on grapes as received at the winery during the seasons of 1911 and 1912 ; 

 and on methods for the control of microorganisms on grapes for wine making. 



Nineteen different organisms were isolated from California grapes, the ma- 

 jority of which were found to be types that are harmful in wine making. On 

 the surface of the green grapes examined were found mostly molds, while as 

 the grapes ripened wild yeasts made their appearance, the true wine yeasts be- 

 ing the last to appear. During storage - and shipment, the organisms (particu- 

 larly molds and wild yeasts) increased rapidly. It was found that this could 

 be checked by crushing the grapes at the winery and adding moderate amounts 

 of sulphurous acid (about 1 gal. of 6 per cent sulphurous acid solution per ton 

 of crushed grapes). 



The method, previously noted (E. S. R., 34, p. 207), of adding moderate 

 amounts of sulphurous acid to the grapes after arrival at the cellar, with sub- 

 sequent application of pure yeast, is again recommended as giving uniformly 

 good fermentations and sound wines. 



A method of dialysis of enzyms, O. A. Val'tera (Izv. Ross. Akad. Nauk 

 (Bui. Acad. Sci. Buss.), 6. ser., No. 13 (1917), pp. 1075-1088, fig. J).— A new 

 method of dialysis is described in which a specially constructed apparatus with 

 collodion sacks is employed. Experiments with the tryptase of yeast indicate 

 that by the use of this method preparations may be obtained with a consider- 

 ably higher activity at a diminished volume. The activity of the enzym is 

 somewhat lowered in the process of dialysis, but the passage of either the enzym 

 or the coenzym through the membrane is prevented. 



The quantitative analysis of small quantities of gases, H. M. Ryder (Jotir. 

 Amer. Chem. Soc, 40 (1918), No. 11, pp. 1656-1662, figs. 8; abs. in Chem. Abs., 

 13 (1919), No. 1, p. 11). — A description is given of an apparatus designed for 

 the quantitative analysis of small quantities of gases, of its manipulation, and 

 of the results of tests made to determine its accuracy. The gases which can be 

 handled in this way are water vapor, carbon dioxid, carbon monoxid, oxygen, 

 hydrogen, nitrogen, and methane. The apparatus is designed to handle quanti- 

 ties varying from a few cubic millimeters to about 1 cc. 



Notes on Folin's direct nesslerization method for the determination of 

 nitrogen, L. Langstroth (Jour. Biol. Chem., 36 (1918), No. 2, pp. 877-380, fig. 

 1).— Two difficulties encountered by the author in the use of the Folin-Denis 

 direct nesslerization method for nitrogen determinations (E. S. R., 36, p. 316) 

 are pointed out. The first was in making known solutions of pure ammonium 

 sulphate check with the standard when run through as in the procedure for 

 total urinary nitrogen, and the second in boiling down the filtrate after pre- 

 cipitation of the blood proteins with m-phosphoric acid without loss from bump- 

 ing. The first difficulty was found to be due to impurities in the sulphuric 

 acid, and can be remedied by a preliminary digestion of the standard solution. 

 It was found that the second difficulty can be avoided by heating with a micro- 

 burner the filtrate in a hard glass tube held just far enough from the horizontal 

 to bring the surface of the liquid half way between the bottom and the mouth 

 of the tube. 



Microchemical nitrogen determination, B. Sjotxema and C. W. G. Het- 

 terschy (Biochem. Ztschr., 84 (1917), No. 5-6, pp. 859-370, fig. 1; abs. in Chem. 

 Abs., 12 (1918), No. 14, p. 1473). — This is a critical discussion of the micro- 

 Kjeldahl method for the determination of nitrogen and the direct nessleriza- 

 tion methods of Folin and Denis (E. S. R., 36, p. 316), together with suggestions 

 for certain modifications in both methods. 



The conclusion is drawn that in the authors' experience the micro-Kjeldahl 

 is to be preferred to the direct nesslerization method, although good results can 

 be obtained by both methods. 



