AGRICULTURAL CHEMISTRY — AGROTECHNY. 313 



mately 25 per cent of carbon dioxid. Cultures of the same species in the same 

 jar with an initial mixture of air and 25 per cent of carbon dioxid showed 37 

 per cent of carbon dioxid at the end of 8 days, with marked reduction in the 

 activity of certain species. Cultures of the same series of fungi in jars with 

 approximately 50 per cent of carbon dioxid in the initial mixture left the mix- 

 ture approximately unchanged at the end of 7 days. Fungus growth was 

 stopped for^certain species, greatly reduced for all, but G of the species tested 

 produced very considerable growth. 



" Cultures of this series of species grown for 8 days in jars with 75 per cent 

 of carbon dioxid in the initial mixture showed that P. roqueforti alone was able 

 to produce fairly strong colonies in this mixture. A mixture of 75 per cent of 

 carbon dioxid with air gives approximately 5 per cent of free oxygen. The close 

 correspondence between the results of gas analysis and comparative culture 

 indicates that the low percentage of oxygen in the open spaces within the cheese 

 accounts for the dominant activity of P. roqueforti in Roquefort and related 

 types of cheese." 



Report of the progress made in the field of milk chemistry and dairying 

 during- the second half of 1912, W. Grimmer {Milchw. Zenthl., Jf2 (1918), 

 Nos. 5, pp. 139-lU; 6y PP- 178-185).— This deals with the literature on milk 

 production, milks of various kinds, milk constituents, changes in milk and its 

 constituents, bacteria in milk, milk enzyms, immune bodies and milk as an 

 antigen, rennet and coagulation by rennet, milk as a food, milk products, dairy 

 machinery, milk supply, and methods for examining milk. 



The chemistry of rubber, B. D. Porritt (London, 1913, pp. VII +96). —This 

 monograph is said to be a concise presentation of the chemistry of rubber. Its 

 contents are as follows: The properties of crude rubber; constitution and de- 

 rivatives; methods of vulcanization; theories of vulcanization; waste rubber 

 and its utilization; and synthetic caoutchouc. A bibliography of 179 titles is 

 appended. 



About the use of red cabbage extract as an indicator for the colorimetric 

 measurement of the hydrogen ion concentration, L. E. Walbum (Biochcm. 

 Ztschr., 48 (1913), No. 4, pp. 291-296; Compt, Rend. Lad. Carlsherg, 10 (1913), 

 No. 2, pp. 227-232). — The red coloring matter of red cabbage was found to serve 

 well as an indicator for measuring the hydrogen ion concentration, and the 

 figures obtained agreed fairly well with those given by the electrometric method. 

 •The indicator worked well in the presence of an appreciable amount of proteins. 

 Neutral salts (up to i^ molecule of sodium chlorid), toluene, and chloroform 

 did not affect the results of the measurements. 



The separation of 6-alanin and 5-valin, P. A. Levene and D. D. Van Slyke 

 (Jour. Biol. Chem., 16 (1913), No. 1, pp. 103-120). — "5-Alanin combines with 

 phosphotungstic acid in the ratio of approximately 1 : 14 by weight, forming 

 a crystalline salt. At 0°, in a solution containing, per 100 cc, 20 gm. or more 

 of phosphotungstic acid in excess of the amount combining with the alanin, and 

 10 gm. of sulphuric acid, the solubility of alanin is only 0.15 gm. per 100 cc. 

 The solubility of 5-valin under the same conditions is 1.21 gm. i)er 100 cc. By 

 alternate crystallization of valin as the free amino acid and of alanin as the 

 phosphotungstate, one can effect a practically quantitative separation of a 

 mixture of the 2 amino acids." 



Examination of hydrocarbon oils and fats, D. Holde (Untersuchung der 

 Eohlenwasserstoffole und Fette so-ivie der ihnen verwandten 8toffe. Berlin, 

 191S, 4. €d., rev. and enl, pp. XVI +596, pis. 2, figs. iiJ).— This edition Includes 

 the examination of vegetable and animal fats and oils. In addition it takes 

 up some of the commodities which are made from fats and oils such as candles, 



