AGRICULTUEAL CHEMISTRY — AGKOTECHNY. 213 



author points out tbat light is a factor iu both oxidation and hydrolysis, but 

 finds the explanation for the latter difficult. He concludes that " filtered butter- 

 fat samples can be satisfactorily preserved iu well-stoppered bottles." 



Except for the fact that heating gave a very slight increase in the acid 

 number no other changes were noticeable. It is therefore concluded that 

 butter fat heated to temperatures up to 50° C. undergoes practically no change. 



The use of the Zeiss immersion refractometer in the detection of watered 

 milk, P. H. Smith and J. C. Reed {Massachusetts 8ta. Rpt. 1909, lit. 1, pp. 

 lJf8-153). — The method recommended by Leach and Lythoe (E, S. R., 16, p. 

 742) was further studied, and on the basis of results obtained with milk from 

 3 herds and some samples which were systematically skimmed and watered, 

 the authors conclude that " the serum of a milk of known purity is not likely 

 to have a refractive index below 40. It seems probable that the refractive 

 index depends, to an extent, upon the stage of lactation of the cow, being 

 highest in the advanced stages, when the animal is giving but little milk. 

 More data are needed, however, to confirm this statement. Rich milk, con- 

 taining 4 per cent or more of fat, has a tendency to give a higher index of re- 

 fraction than thin milk (less than 4 per cent fat). This rule, however, does 

 not always hold true. 



" Many milks, especially those produced by Jerseys and Guernseys and their 

 grades, can be adulterated with 10 per cent of water, or 5 per cent of water 

 and 5 per cent of skim milk, and escape detection by means of the index or 

 refraction. In case of very rich milk, i. e., pure milk containing 6 per cent of 

 fat, it may be possible to add 20 per cent of water, or 10 per cent of water 

 and 10 per cent of skim milk, without positively detecting its presence by the 

 aid of the refractometer. 



" It is believed that the Zeiss refractometer will prove very helpful in the 

 detection of added water in milk. The evidence furnished, however, must be 

 considered in connection with that secured by direct chemical analysis. It is 

 believed that the percentage of ash in milk is likely to prove fully as helpful 

 in many cases as the index of refraction in detecting the presence of added 

 water. Mixed milk falling substantially below 0.70 per cent of ash must be 

 regarded with suspicion, and that testing below 0.65 per cent of ash as 

 watered." 



Catalase estimation in milk, N. Gerber and A. Ottikeb (MUchiv. Zenthl., 

 6 {1910), No. 7, pp. 316-327, figs. 3).— A discussion as to the use of the Lobeck 

 apparatus (E. S. R., 23, p. 13) for determining the catalase in milk and utiliz- 

 ing the results for differentiating normal from pathologic and colostrum milks 

 and pasteurized from unpasteurized milk. The results of the tests are ap- 

 pended. 



Estimation of butter and coconut fat in margarin, S. H. Blichfeldt {Jour. 

 Soc. Chem. Indus., 29 {1910), No. 13, pp. 792-79Jt, figs. 2).— The author devised 

 a method and an apparatus, which is illustrated, to overcome some of the diffi- 

 culties encountered with the Polenske method (E. S. R., 15, p. 850). 



Examination of the constituents of coco butter; composition of coconut 

 oil, A. Haller and A. Lassieur {Ahs. in Chem. Ztg., 34 {1910), No. 57, p. 

 509). — In order to render the copra edible it is heated with superheated steam, 

 which decolorizes it and drives oft" noxious odors. Coco butter owes its dis- 

 agreeable odor to an oil the chief constituent of which is methylheptylketon 

 and methylnonylketon, but which also contains small quantities of an uniso- 

 lated aldehyde, which is optically active. 



Determining lactic acid quantitatively by estimating' the amount of 

 aldehyde split off, O. von FtJRTH and D. Charnass (Biochem. Ztschr., 26 

 (1900), No. 3-4, pp. 199-220, figs. 2).— From the results of the works the authors 



