AGRICULTURAL CHEMISTRY AGROTECHNY. 115 



For conducting the test 16.3 cc. of the milk is placed in a beaker with 

 1 cc. of 1 : 500 phenolphthaleiu and the acidity is neutralized with standard 

 alkali, cai-e being taken that the color is brought to a good deep pink. Two 

 cc. of neutral formaldehyde solution, 40 per cent, is then added and the mix- 

 ture titrated with standard alkali solution until the pink coloration reap- 

 pears. The number of cubic centimeters of alkali used represents the per- 

 centage of casein in the milk. 



The time required for the test is about 2 minutes. The test is recommended 

 as a basis for paying for milk in cheese factories. 



The analysis of unsweetened evaporated milk, C. A. A. Utt {Jour. Indus, 

 and Engin. Chem., 5 (1913), No. 2, pp. 168, 169). — The sample is mixed and if 

 fat is seen on the surface, it is necessary to warm it after adding a little 

 sodium hydroxid. For the estimation of the fat, weigh 4.5 gm. of the milk 

 into a 10 per cent Babcock bottle with from 6 to 8 cc. of sulphuric acid 

 (specific gravity 1.8) ; shake until a chocolate brown color is obtained, and 

 place for from 15 to 20 minutes in boiling water. After cooling add hot 

 dilute sulphuric acid 1 : 1 until the bottle is two-thirds full, and centrifuge 

 for 5 minutes. " Fill to the neck w'ith hot, half-strength sulphuric acid and 

 whirl 3 minutes. Add hot water to bring the fat column into the neck of the 

 bottle and whirl 2 minutes. Read at 120 to 125° F. from the bottom of the 

 column to the extreme top of the meniscus. The reading multiplied by 4 gives 

 the percentage of fat." 



Laboratory and field assay of arsenical dipping fluids, R. M. Chapin 

 ([/. S. Dept. Agr. Bui. 76 (1914), pp. 11, fig. i).— There are various factors 

 which tend to render arsenical dipping fluids of uncertain composition. Chiefly 

 amongst these are the use of low grade chemicals in their preparation, evapo- 

 ration, or leakage from the bath, oxidation of arsenious oxid to arsenic acid, 

 especially through the agency of micro-organisms, and the converse phenomenon 

 of reduction to arsenate. There is therefore needed an analytical control of 

 the dipping solutions, and laboratory tests are described for actual arsenious 

 oxid and total arsenic, which can be executed by persons who have but a 

 limited training in chemistry. In addition a portable testing outfit is described 

 which has been devised for bureau inspectors in the field and with which it is 

 possible, without any chemical knowledge whatever, to determine, at the side 

 of the vat and in a few minutes, the strength of the arsenical solution prepared 

 according to the standard formula. The apparatus required is illustrated and 

 the criterions for judging the results obtained by the methods are stated. 



Determination and detection of methyl alcohol, T. von Fellenberg {Mitt. 

 Lehensm. Untersuch. u. Hyg., Schweiz. Gsndhtsamt., 4 {1913), No. 3, pp. 122- 

 146, figs. 2). — This deals with a quantitative physical method for determining 

 methyl alcohol, which in principle is similar to that used by Rose in determining 

 higher alcohols. It is shown that if a solution containing a definite percentage 

 of alcohol is shaken with ether, the point at which the ether-water, etc., solution 

 separates differs with the kind of alcohol present. With methyl alcohol the 

 water-alcohol layer becomes greater while with ethyl alcohol it becomes less. 



For the method a special form of apparatus has been devised. Its use for 

 detecting methyl alcohol in brandies is shown, and the work includes a method 

 for concentrating solutions containing methyl alcohol, which is done by salting 

 out the ethyl alcohol and higher alcohols with potassium hydroxid. This allows 

 the detection of 1 : 100,000 parts of methyl alcohol by the Deniges method. 

 Methyl alcohol is also shown to be a product resulting from the fermentation 

 of fruit residues. 



Besearch studies on the curing of leaf tobacco, W. W. Gabner, C. W. 

 Bacon, and C. L. Foubeet {U. 8. Dept. Agr. Bui. 79 {19U), pp. 40).— This is a 



