CHEMISTRY. 1051 



upon the fact that the principal volatile fatty acids of butter fat are different from 

 those of cocoanut fat. In this method the caprylic acid, which is present in large 

 quantities in cocoanut fat but in only small quantities in butter fat, is removed by 

 means of silver sulphate, which does not act upon the butyric acid. 



Contribution to the knowledge of cotton-seed oil and the Halphen reac- 

 tion, K. Fischeb and II. Peyau (Ztschr. Untersuch. Nahr. ». Genussmtl., 9 (190.5), 

 No. ..-'. pp. 81-90). — The results of the investigations indicate that the Halphen 

 reaction can not be depended upon for the detection of cotton-seed oil in other fats, 

 since the cotton-seed oil can lie so treated as to render the Halphen reaction nega- 

 tive. The phytosterin test is, therefore, considered essential in determining the 

 presence of cotton-seed oil in lard and other animal fats when the index of refraction, 

 iodin number, saponification number, and color reaction have not clearly shown 

 such an adulteration. 



On a color reaction of cotton-seed oil, G. Halphen {Ann. Chim. Anal., 10 

 (190.5), No. 4, pp. 140-143). — This is a brief discussion on the cause of the coloration 

 in Halphen's test for cotton-seed oil. 



On the detection of formaldehyde in milk, E. Nicolas (Cotnpt. Rend. Soc 

 Biol. [Paris], .58 (1905), No. 15, pp. 697, 698). — The greenish fluorescence obtained 

 in milk containing formalin by the addition of amidol or diamido-phenol is believed 

 to permit of the recognition of this preservative when present in quantitiesof 1 : 500,000 

 or even less. In applying this test the casein may be precipitated by acetic or lactic 

 acid and a few crystals of amidol added to the filtrate. 



A study of methods for the determination of formaldehyde, R. H. Williams 

 (Jour. Amer. Chem. Soc, 27 (1905), No. 5, pp. -596-601). — This is a comparison and 

 criticism of the Legler, hydrogen peroxid, iodometric, and potassium cyanid 

 methods of determining formaldehyde. The author's conclusions are summarized 

 as follows: 



"The iodimetric method is rapid and accurate, and preferable for pure dilute 

 solutions. 



"The hydrogen peroxid method is the most satisfactory for strong impure solutions. 

 The time necessary for a complete oxidation is widely variable, depending upon 

 concentration and temperature. 



"The potassium cyanid method is recommended for dilute impure solutions. The 

 results are lower than those obtained by the oxidation methods. 



"The end-point in the Legler method is not satisfactory, which fact, as well as the 

 low results, must be attributed to causes other than the influence of strong acids on 

 hexamethylenetetrarnin. 



"Paraformaldehyde, when present, counts as formaldehyde. 



" The discrepancy in the results obtained by the two different types of methods is 

 due to conditions inherent in the methods themselves, not to the presence of impuri- 

 ties or to a polymerized form of formaldehyde. Apparently, either the condensation 

 reactions are not complete, or a small part of the formic acid produced by the oxida- 

 tion reactions is oxidized further, giving high results." 



A colorimetric method for the detection and estimation of formaldehyde, 

 F. Bonnet, Jr. (Jour. Amer. Chem. Soc, 27 (1905), No. .5, pp. 601-605).— The method 

 proposed depends upon the color reaction of morphine with formaldehyde by which 

 it is stated that quantities of formaldehyde as small as 4 parts in 1,000,000 can be 

 detected. 



The test solution used is made by dissolving 0.35 gm. of white crystalline morphine 

 sulphate in 100 cc. of cold strong chemically pure sulphuric acid. In applying this 

 test to milk about 60 cc. of the sample is placed in an evaporating dish and 1 cc. of 

 the morphine solution in a watch glass is floated upon the surface. The color pro- 

 duced in this test solution by the vapor of the formaldehyde varies from pink to 

 dark blue, according to the amount of preservative present. When formaldehyde is 



