10 EXPERIMENT STxVTlON RECORD. 



A trial of the polariscopic method for the determination of gliadin, G. W. 

 SiiAW {Jour. Aiiicr. Cliciii. ,s'oc., .i!) {11)01), A'o. /,?, /;/>. I7',7~n'50). — From an 

 ex])erinioiit<il study of this iiicthod, (lie author is decidedly of th(! opinion that 

 it is worthy of inueli more extended use and that if precautions are taken to ninke 

 corrections for the effect of other optically active bodies there are fewer oppor- 

 tunities for error than with the ordinary methods of determining nitrogen. 



" In our experience with the method it was always found necessary to make 

 two polarization determinations, tlie first of the original solution, and the 

 second after separating the r)rotein liodies by the use of a concentrated solution 

 of mercuric nitrate, and then making the required correction to give tlie true 

 gliadin reading." 



On the analytical estimation of gliadin, W. P]. Mathewson {Jour. Amcr. 

 Clicni. Soc, SO {1!)0S), A'o. /, pp. ?'/-,S7). — In a comjiarison of different methods 

 of extracting gliadin it was found that S to 17 per cent more nitrogenous matter 

 was extracted when the proportion of material to solvent (cold 70 per cent 

 alcohol) was 4 gm. to 100 cc. than when 4 times as much flour was used. 



"After drying 6 hours in the water oven, 10 to 20 per cent less gliadin was 

 obtained by extracting with cold solvent. With the hot water solvent the figures 

 were nearly the same, being slightly lower. Pure gliadin remains soluble in 

 dilute alcohol after the same treatment. No tendency for glutenin to i-emove 

 gliadin from its alcoholic solutions by absori)tion or with the production of a 

 solid solution could l»e demonstrated. Propyl alcohol of constant boiling point 

 (70 per cent by weight) used in an extraction apparatus gave results probably 

 no more accurate than the otliers. Anhydrous phenol dissolves a high per- 

 centage of protein matter from the flour. The dissolved matter is not pure 

 gliadin, liowever, nor does it seem to consist of gliadin with but one other 

 protein." 



Experiments upon Barfoed's acid cupric acetate solution as a means of 

 disting'uishing' glucose from maltose, lactose, and sucrose, F. C. Hinkel and 

 H. C. Sherman (Jour. Amcr. Chcm. Soc, 2!) {1001), No. 12, pp. ll'i'i-ll'il). — 

 In the authors' hands, this method gave good results, being efficient for the de- 

 tection of 0.0004 gm. glucose, either alone or in the presence of maltose, lactose, 

 or sucrose up to 0.02 gm. 



"Reduction due to disaccharid occurs if too much either of sugar or of acid 

 be present, or if the heating be too prolonged. In order to effect complete 

 destruction of the glucose, so that the filtrate might be utilized in testing for 

 maltose or lactose, it was necessary to limit the amount to about 0.002 gm. of 

 glucose to 5 cc. of the reagent. It appears that the test requires very careful 

 regulation as to details of manipulation and amount of sugar tested, but under 

 such restrictions is capable of greater usefulness than has generally been appre- 

 ciated. . . . 



" On account of the difficulty of securing an exact degree of acidity in the 

 cupric-acetate solution, each chemist should demonstrate the efficiency of his 

 reagent, as well as verify his manipulation, by check experiments upon known 

 sugar solutions covering the probable range of composition of the unknown 

 solutions to be tester!." 



The estimation of starch in potatoes by means of specifi.c gravity, Foxn 

 {Ztschr. Spiritunindus., 30 {1901), No. 21; ahs. in Bui. Assoc. Chiiii. Sucr. ct 

 Distill., 25 {1908), No. 1, pp. 691, 692).— A modified method of estimating the 

 starch content of potatoes from their specific gravity is proposed. 



A new method of determining the water which fl.our will absorb, J. F. 

 Hoffmann and R. Ploetz {Ztschr. Spiritusindus.. 31 (1908), No. .7, pp. .'i2, 

 .'i3). — In the method described the sample, after wetting with water, is pressed 



