312 EXPERIMENT STATION RECORD. [Vol. 40 



The moisture in a 10 gm. sample is determined in the usual way In a tall, 

 lipped 100 cc. aluminum beaker. After the beaker is weighed to determine 

 the loss of moisture, the fat is extracted with successive portions of petroleum 

 ether, which is removed by decantation. The excess of petroleum ether is re- 

 moved by evaporation and the percentage of fat determined by difference upon 

 reweighing the beaker and its contents. The salt may then be determined by 

 titration. 



The method is said to be very rapid and to give results as accurate as those 

 obtained by the official methods. 



Report of the committee on the analysis of commercial fats and oils, W. D. 

 Richardson {Jour. Indus, and Engin. Chem., 11 (11)19), No. 1, p. 69). — This 

 report contains a few corrections to the tentative standard methods for the 

 sampling and analysis of commercial fats and oils, previously noted (K. S. R., 

 38, p. S04), and new methods for the melting point and cloud test determina- 

 tions. 



Quantitative determination of soluble starch in the presence of starch 

 and its hydrolytic cleavage products, J. C. S.\t \i.i. (Jow. Atner. Chem. Soc, ^1 

 {1919), No. 1. pp. 107-11-'). The method described consists essentially in 

 precipitating the Lodld from Its solution of dextrins and lower carbohydrates 

 by ammonium sulphate. The precipitate is washed free from the other 

 carbohydrates by successive portions of B saturated solution of ammonium sul- 

 phate and heated in water suspension to drive off the iodin. The soluble 

 starch is then nydrolyzed by acids and estimated by the usual methods for 

 determining dextrose. 



A method for the preparation of soluble starch, J. C. Smalt. (Jour. Aim r. 

 Chem. so,-., .;./ [1919), No. i. pp. tlS-120, fio- D— The following method has 

 been found by the author to be more satisfactory than the Limner method for 

 the preparation of a soluble Starch containing a minimum of carbohydrate: 



The starch is nydrolyzed by means of redistilled 95 per cent alcohol in the 

 presence Of a small amount of concentrated hydrochloric acid (si». gr. 1.19). 

 At the end of from 6 to 15 minutes the acid is neutralized with sodium bicar- 

 bonate, the neutral alcohol filtered off, and the starch washed with several 

 additions of fresh alcohol. 



Analyses of samples Obtained by this method are reported which indicate 

 that the principal factors Influencing the conversion of starch to soluble starch 

 in this process are the time of exposure, concent ration of acid, and density of 

 the starch suspension. A study of the effect of concentration of acid showed 

 that the greatest yield of soluble Starch is obtained when 0.7.") volumes per cent 

 of concentrated hydrochloric acid in 95 per cent alcohol is used and the hydro- 

 lysis continued at the boiling temperature for 10 minutes. The indication that 

 under the proper conditions starch seems to be wholly converted to soluble starch 

 before further hydrolysis occurs is considered to support the idea that soluble 

 starch is a hydrated starch from which maltose has not yet been split off. 



An improvement applied to the volumetric determination of reducing 

 sugars, D. Stderskt (Bui. Assoc. Chim. 8uor. et Distill. So (1917). Xo. 1-3, p. 

 89). — In order to bring about a more rapid settling of the cuprous oxid precipi- 

 tate in the usual determination of reducing sugars, the author recommends the 

 addition of magnesium sulphate to the copper sulphate solution in the pro- 

 portion of 5 gm. MgSOi to 34.64 gm. CuSO« dissolved in 500 cc. of water. 



Determination of glucose with hypoiodid, R. YYii.lstatter and G. Schudel 



(Ber. Dritt. chem. Oesell., 51 (1918), No. 8-9, pp. 780, 781).— It Is stated that 



plucose can be determined quantitatively by means of a hypoiodid solution, 



even in the presence of fructose or sucrose, If certain precautions are ohserved. 



The details of the method are as follows: 



