514 EXPERIMENT STATION RECORD. 



filter. Transfer 50 cc. of the filtrate to a 50 to 55 cc. flask ; add 1 cc. of a 

 saturated solution of aluminum suli)bate ; make up to 55 cc. ; filter and polarize 

 in the 60 cm. tube. The observed reading multiplied by 2 is the direct read- 

 ing=D. Transfer a second portion of 50 cc. to a 50 to 55 cc. flask ; add 2.75 cc. 

 of hydrochloric acid of speciflc gravity 1.18 ; invert, following the Herzfeld 

 routine, or add 5 cc. of acid and invert, follovring the original Clerget pro- 

 cedure; add a small quantity, about 0.1 gm. of zinc dust; make up to the 

 mark ; filter and polarize in a 60 cm. tube. The observed reading multiplied 

 by 2 is the inverted reading=I. 



" Calculate the percentage of cane sugar from the expression — Sugar per- 

 centage — ;^; — —where t is the temperature at which the analysis is performed, 



and X is the appropriate constant." 



Judg'ing' the quality of sugar beets by their content of injurious nitrogen, 

 G. Friedl iOsterr. Vngar, Ztschr. Zuckerindus. u. Landw., 39 {1910), No. 2, pp. 

 235-239, figs. 2). — The author finds that by estimating the injurious nitrogen in 

 sugar beets a good index can be obtained as to the purity of the juice after 

 saturation. A definite relation evidently exists between this nitrogen and 

 Krause's coeflicient of purity. 



A colorimetric method for estimating the injurious nitrogen in sugar beets, 

 G. Friedl (Osterr, Vngar. Ztsclir. Zuckerindus. u. Landw., 39 (1910), No. 2, pp. 

 2JfO-246). — The author proposes to determine the injurious nitrogen in sugar 

 beets by precipitating the proteids with Barnstein's modification of Stutzer's 

 reagent, and comparing the depth of color of the filtrate with a standard 

 Fehling's solution containing some Schweinfurtli green. 



Methods and standards in bomb calorimetry, J. A. Fries ( U. S. Dept. Agr., 

 Bur. Anim. Indus. Bui. 12.'t, pp. 32; Pennsijlvania t^ta. Rpt. 1909, pp. 321-3.',3)-^ 

 In the cooperative investigations reported, the undertaking was. independently 

 of all previous determinations of the heat of combustion of any organic sub- 

 stances, to determine anew the heat of combustion of benzoic acid, using the 

 improved form of bomb calorimeter previously noted (E. S. R., 21, p. 209). 



The water value of the bomb calorimeter was determined by the computation 

 of component parts, by the electrical method, and by a third method which was 

 tried because the author did not consider the results obtained by the other 

 methods satisfactory. 



The principle of the third method consists " in burning equal charges of a 

 substance in the bomb first, under exactly the same conditions as when a heat 

 determination is made and, secondly, after having, without changing any of 

 the external conditions, such as level of water, etc., reduced the water equiva- 

 lent of the system. The same amount of oxygen is used in each case. From 

 the difference in rise of temperature and the difference in water equivalent 

 it is possible to determine very accurately the water value of the calorimeter. 



" By this method it is possible, first, to use a substance of unknown or only 

 approximately known heat of combustion and an oxygen supply of unknown 

 purity to determine the water equivalent of the apparatus and then by means 

 of this new water equivalent and the same determinations to work out accu- 

 rately the heat of combustion of the substance used, and also to determine the 

 correction for impurities in the oxygen, if any such were present." 



The determinations of benzoic acid are reported in full and the use of the 

 bomb calorimeter under different conditions is discussed. 



" From his experience with various substances and because of the value 

 obtained for benzoic acid as described in this paper, the author in conclusion 

 desires to urge all persons using the bomb calorimeter for scientific work where 

 results are to be published, for the sake of uniformity and comparability of 



