614 EXPERIMENT STATION RECORD. [Vol. 43 



tlie results of a study of tlie present standard of turbidity in water analysis as 

 determined by coniparing samples of standard turbidity used by different State 

 and municipal water laboratories in a special turbidimeter, the construction 

 and operation of which are described in detail. 



This study has shown the present standard of turbidity to be inaccurate, the 

 variations from the average amounting in some cases to over 50 per cent. It 

 is thought that these variations could be eliminated by having all the standards 

 prepared by the Bureau of Standards, and the possibility is suggested of pre- 

 paring standard samples of dry powdered silica sufficiently uniform in size of 

 particle to use directly by suspension in the appropriate amount of distilled 

 water. 



Critical study of methods for the detection of methyl alcohol, A. O. Get- 

 TLER {Jour. Biol. Chevi., 42 {1920), No. 2, pp. 311-328).— An extensive review of 

 the literature on methyl alcohol is reported, together with a critical study of 58 

 selected tests as applied to over 250 liquors and 700 human organs. As a result 

 of this study typical procedures for the detection of methyl alcohol in liquors 

 and tissues, involving a number of color reactions and a few crystal-producing 

 tests, are described in detail. A bibliography of 123 titles is appended. 



The diazometric determination of phenol, and certain of its homologs, 

 R. M. Chapin {Jour. Indus, and Engin. Chem., 12 {1920), No. 6, pp. 568-570). — 

 The author, from the Bureau of Animal Industry, U. S. Department of Agricul- 

 ture, reports a study of the possibility of applying the diazometric method to 

 determine the strength of cresylic solutions used in official disinfecting opera- 

 tions. 



The method depends upon the quantitative coupling of phenols with diazonium 

 salts to form insoluble hydroxyazo compounds, as in the equation 



CeHsOH+N : N(OH) Ar^HO.CeHiN : N.ArH.O. 



The conditions found to be essential for accurate results with the lower 

 monohydric phenols of the benzene series consisted principally in working with 

 as concentrated solutions as practicable and using as a buffer, to maintain tlie 

 lowest possible concentration of H-ion without notable formation of isodiazo 

 compounds, basic lead acetate in the presence of sodium acetate. The tech- 

 nique of the procedure is described in detail with the precautions that must be 

 observed to secure accurate results. 



Preliminary experiments upon the use of this method as a field test for 

 cresol solutions used as animal dips are reported to be encouraging. " The re- 

 sults are not affected by the soap present in such solutions, while the basic lead 

 acetate employed appears to precipitate and render innocuous organic matter 

 derived from the animals (hogs)." 



A quantitative method for determination of vitamin, R. J. Williams 

 {Jour. Biol. Chem., ^2 {1920), No. 2, pp. 2.19-265, fig. 1).—The method described 

 differs from the one previously suggested (E. S. R., 41, p. 670) in that instead 

 of measuring the growth of single yeast cells, the growth of a large number of 

 cells under defined conditions is measured by a gravimetric determination which 

 is said to give more accurate results than the single cell method. 



The results obtained are expressed as the " vitamin number " which is de- 

 fined as the " number of milligrams of yeast produced by the addition of its 

 extract minus that produced in a control solution, under given conditions and 

 within certain limits, computed to 1 gm. of the original material tested." 



Certain precautions that must be taken in both the single cell and gravi- 

 metric methods are outlined, and some of the facts discovered in the applica- 

 tion of both procedures are discussed. It was found that a solution containing 

 ammonium sulphate and asparagin was not improved as a nutrient medium for 



