10 EXPEBIMENT STATION RECORD. [Vol. 37 



slotted brass tubes terminating in a solid pointed end. The sampler can be 

 inserted to the full length of the bag before any material can enter the 

 sample chamber. As representative a sample of the material as is practically 

 possible is thus obtained. 



The necessity of drafting standard methods for sampling fertilizers and the 

 recognition of such methods as official is indicated. 



The influence of carbohydrates on the accuracy of the Van Slyke method 

 in the hydrolysis of casein, E. B. Hart and B. Sure {Jour. Biol. Chctn., 28 

 (1916), No. 1, pp. 241-249). — Experimental data obtained from hydrolysis and 

 amlno-acld nitrogen distribution determination according to the Van Slyke 

 procedure (E. S. II., 26, p. 22) for pure casein and casein with dextrose, 

 sucrose, starch, and xylan, respectively, are reported in tabular form. 



The results indicate that the presence of these carbohydrates during the 

 hydrolysis brings about a total redistribution of the amino acids, varying with 

 the nature of the carbohydrate employed. Marked changes were especially 

 apparent in the hexone bases and a decided loss of nonamino nitrogen occwred 

 in the presence of xylan. 



The authors conclude from the results of Gortner (E. S. R., 36, p. 108) and 

 the present results submitted that the method of direct hydrolysis for the esti- 

 mation of amino acids in feeding stuffs by Van Slyke's method is inapplicable, 

 and that the results so secure<l will be inaccurate. The use of factors is 

 deemed to be Impossible because of the variation of the nature and quantity 

 of the carbohydrates in feeding stuffs, and because of this variation the results 

 obtained are not even of comparative value. 



It is further concluded that " in the present unsatisfactory status of the 

 methods for estimating the amino acids In the complex protein-carbohydrate 

 mixture of feeding stuffs the only reliable procedure for obtaining an insight 

 Into the nutritive worth of the proteins In such a mixture will be the bio- 

 logical one." 



Methods for the estimation of mixtures of four or more carbohydrates, 

 involving oxidation with bromJn, Edith G. Wilson and W. R. G. Atkins 

 {Biochem. Jour.. 10 (1916), No. 5, pp. 504-621, fig. i).— Analytical data sub- 

 mitted and di-scusscd show that glucose ami maltose are quantitatively 

 oxidized by bromin at room temperature when allowed to stand In a saturatetl 

 solution. Fructose is not oxidized at all or only to a very small extent by 

 bromin under these comlltlons. In the pre.sence of tenth-normal sulphuric 

 acid there Is slight loss of fructose In 66 hours at room temperature. 



For the analysis of a mixture of sucrose, maltose, glucose, and fructose the 

 following scheme Is described: The sucrose !s determined by polarlzatlou and 

 reduction before and after treatment with Invertase. The resulting mixture 

 of reducing sugars is tre;Ued with bromin under standard conditions of acidity 

 and temperature, by which the aldehydlc sugars, glucose and maltose, are 

 oxidized. The ketonic sugnr remains behind. The reducing power of the 

 solution may then be taken as due to fructose alone. The rotations due to 

 the fructose and sucrose are then allowed for in the Initially determined 

 rotation. This gives the rotation due to glucose and maltose. The reduction 

 due to fructose Is subtracted from the Initial reduction, which thus gives 

 the reduction due to glucose and maltose. From these data equations can 

 be constructed for determining the amounts of the two remaining sugars. 



It is indicated that the addition of dilute alkali to a solution of glucose, 

 fructose, or maltose produces a large temporary increase in its reducing power. 

 The necessity of keeping solutions neutral or very faintly acid in analytical 

 work Is obvious. Some Indication has been obtained of the formation of a 



