AGRICULTURAL CHEMISTRY — AGROTECHNY. 415 



employed. After removal of hydrogen i>eroxld by means of reducing agents, 

 positive tests may, however, be obtained." 



The extent of the proteolysis in cheese determined by formol titration, 

 O. GiiATz {Kiserlet. Kozlem., 15 (1912), Xo. 2, pp. 281-2S8). — The forniol 

 (formaldehyde) titration method (E. S. R., 19, p. 808) as a means for de- 

 termining the extent of proteolysis measured by the amount of carboxyl 

 groups is deemed satisfactory for studying the proteolytic changes taking 

 place in cheese. The results obtained by this investigation compare well with 

 the figures given for monoamine acids by precipitation with phosphotungstic 

 acid. 



A few observations on starch grains and the use of the counting^ chamber 

 as an aid for the quantitative determination of adulteration in vegetable 

 powders, C. Hartwich and A. Wichmann {Arch. Phann., 250 {1912), pp. 452- 

 471). — This deals with the use of the counting chamber for determining stone 

 cells and clove stems in clove powders, sandal wool in saffron powder, and the 

 variety of starches in a mixture. 



About the chlorzinc-iodid reaction of cellulose, I. V. Xowopokrowsky 

 {Izv. Imp. St. Pctcrl). Hot. Sada {Bui. Jard. Imp. Bot. St. Pctersb.), 11 {1911), 

 No. 4-5, pp- 109-116). — As this reaction, while reliable, is very capricious, a 

 study was made to determine the best procedure for applying it, and conse- 

 quently of the behavior upon cellulose and its products of the individual con- 

 stituents which make up the reagent. 



In most of the chlorzinc-iodid solutions the amount of potassium iodid is so 

 large that the coloration obtained is not typical, and at times it is violet er 

 red instead of blue. If small amounts of potassium iodid and iodin are taken, 

 the color becomes typical, but the intensity of the color suffers. 



It is stated that the most satisfactory results can be obtained by the use of 

 separated solutions. The preparation is treated for a few seconds with 1 

 drop of a 1 per cent iodin and 1 per cent potassium iodid solution and then 

 with a strong zinc chlorid solution (2 parts of zinc chlorid to 1 part of water). 

 The preparation is dropped into the zinc chlorid solution, and it must be 

 colored intensely blue in from 1 to 1^ minutes. If it is not colored properly, 

 a little potassium iodid is added. 



The method is given preference over those of Schultze, Behrens, or von 

 Hohnel. 



Acidity in silage: Method of determination, C. O. Swanson, J. W. Calvin, 

 and E. Hungerford {Jour. Amer. Chcm. Soc, S5 {191S), No. 4, pp. 416-483). — 

 Investigators, as a rule, determine the acidity in silage by extracting the acid 

 with either water or alcohol and titrating with a standard alkali solution, 

 using phenolphthalein as an indicator. Esten and Mason (E. S. R., 27, p. 

 204), Hart and Willaman (E. S. R., 28, p. 109), and Dox and Neidig (E. S. 

 R., 29, p. 712) used water as the solvent, although with certain kinds of 

 silage *it yields an extract which is difficult to filter. Alcohol as a solvent has 

 not been thoroughly studied by experiment station chemists. 



This work was done on several kinds of silage, and on different samples of 

 the same silage. In all cases, however, the ratio between the silage and the 

 solvent was 1 : 10. In order to make the results comparative, they were cal- 

 culated to acetic acid. The presence of carbon dioxid in silage had little effect 

 upon the acidity figures, although it is belieted advisable to use recently boiled 

 water for the extraction. Fineness of grinding was found to have consider- 

 able influence upon the ultimate results. 



Upon comparing the acidity in tke water and alcohol extracts. It was noted 

 that alcohol was the more efficient solvent, but 50 per cent alcohol was nearly 



