312 EXPERIMENT STATION RECORD. 



hydrogen ion concentration. The time of coagulation was noted in these mix- 

 tures, and in this way was shown to be directly proportional to the concentra- 

 tion of the hydrogen ions. 



In adding the acetate-acetic acid mixture a zonal change in the milk was 

 noticeable, and simultaneously, a change in the surface tension. Up to a hydro- 

 gen ion concentration of 0.56X10 — " no change in the mixture was noticeable, 

 but from 0.64X10—" to 1.29X10—^ a diffuse clouding was seen, and at 1.29 X 

 10—' the casein was precipitated. 



From this it was concluded that the coagulation of milk through acid is a 

 function of the actual hydrogen ions. The fact that casein is precipitated from 

 milk at 1.29X10 — * led the author to believe that the reason purified casein is 

 only precipitated at 2X10—° is because during the process of purification some 

 changes in its make-up take place. 



Two processes, 1. e., the forebreak and the separation of the curd, which occur 

 in the manufacture of Emmental cheese, could be explained by some of the find- 

 ings with the acetate-acetic acid mixture. Both are i^ependent upon an op- 

 timum of hydrogen ion concentration; that for the forebreak is 0.45X10—', 

 and that for the separation is 1.8X10—'. 



The effect of the salts of the rare earths upon the coagulation of milk by 

 rennet, A. Frouin and V. Mercier (Compt. Rend. Soc. Biol. [Paris], 74 (1913), 

 No. 17, pp. 990, 991; als. in Internat. Inst. Agr. [Royne], Mo. Bui. Agr. Intel, 

 and Plant Diseases, 4 (1913), No. 7, p. 1099). — The metals studied were in the 

 form of sulphates of cerium, lanthanium, neodymium, praseodymium, samarium, 

 and thorium. The results showed that coagulation of milk is hastened by the 

 presence of these salts. 



Does milk contain phosphatids? Y. Njegovan (Biochem. Ztschr., 54 (1913), 

 No. 1-2, pp. 78-82). — In this investigation the sodium sulphate method (E. S. K., 

 28, p. 610) was used. 



As a result the author asks whether we are justified in believing that milk 

 contains phosphatids. The small traces of phosiAorus which are obtained by 

 the alcoholic extraction undoubtedly can be attributed to the presence of decom- 

 position products of casein. This is demonstrated by the fact that repeated 

 extraction of casein always yields phosphorus in the extracts. 



Casein (Merck) prepared according to Hammarsten's method is slightly 

 soluble in hot absolute alcohol and the alcoholic solution on evaporation yields 

 phosphorus. The small amounts of phosphorus noted in the ether and chloro- 

 form extracts are due to the fact that these solutions contain particles of 

 insoluble substances which do not filter out. Sodium sulphate is said not to 

 affect the solubility of phosphatids. 



The dominance of Roquefort mold in cheese, C. Thom and J. N. Currie 

 (Jonr. Biol. Chem., 15 (1913), No. 2, pp. 249-258, figs. 2).— The purpose of this 

 investigation was to obtain information relating to the gases within Roquefort 

 cheese and their relation to the growth of PenicilUum roqueforti. 



An " analysis of the gas collected from the air spaces in Roquefort cheese 

 (both imported and made experimentally) shows that the percentage of free 

 oxygen is low, in no case among those tabulated rising above 7 per cent. Car- 

 bon dioxid appears in proportions ranging from 21 to 40 per cent. The per- 

 centage of carbon dioxid is highest in comparatively fresh-made cheese, where 

 it arises both from respiration of the micro-organisms present and as a by- 

 product of the decomposition of lactose by bacteria. From the maximum figure 

 the percentage falls slowly by diffusion. No hydrocarbons were found. Hydro- 

 gen, if present, was in very small amount. 



" Cultures of 22 species of Penicillium and 5 species of Aspergillus grown in 

 a Novy culture jar for 19 days produced an atmosphere containing approxi- 



