716 EXPERIMENT STATION RECORD, 



solution is added until precipitation is complete; then the bulk of the mixture 

 is noted, and it is filtr-red and polarized. The polarization, after allowance is 

 made for the dilntious brought about by the mercuric acetate and phospho- 

 tungstic acid solutions, shows the percentage of saccharose. 



Various saccharine solutions were examined by this method, and the amount 

 originally added was found. The method can be used for examining sweet 

 wines, fruit juices, marmalades, sirups, dried milk, etc. 



The influence which peptone has on the determination of sugar by Feh- 

 ling-'s solution, A. Bernardi {Biochem. Ztschr., 41 (1912), No. 1-2, pp. 160-164; 

 (lbs. in Zentbl. Physiol., 26 {1912). No. 17, p. 766).— High results are obtained 

 by the gravimetric method if peptones are present. 



The quantitative determination of glucose in the presence of other sub- 

 stances according to G. Bertrand's method, M. Rosenblatt {Biochem. Ztschr., 

 43 {1912), No. 5-6. pp. y,7S-/,S0).— Although it is claimed (E. S. R., 27, p. 714) 

 that no polarimetric method, even when foreign optically active bodies are 

 absent, is very sensitive when minute amounts of sugar are present, G. Ber- 

 trand's method " has been used by the author with success, especially where 

 glucose was present in a solution containing amino acids and similar bodies. 

 While the substances which interfere may be removed with a satisfactory pre- 

 cipitating agent, this is not always necessary, because certain bodies which 

 interfere with the optical activity may be safely disregarded when determining 

 sugar by the Bertrand method. 



In this connection solutions containing glucose and glycocoll, alanin, leucin, 

 tyrosin, asparaginic acid, asparagin, betain, glutamin hydrochlorate, urea, 

 Witte peptone, or Chapoteaut peptone, were examined without removal of the 

 interfering bodies. 



The polarimetric determination of starch, C. J. Lintner {Abs. in Chem. 

 Ztff., 36 {1912), No. 68, p. 639). — The modification proposed by Weuglein in 

 which the solution of starch is brought about by sulphuric acid (specific 

 gravity 1.7), after the addition of water, has given considerable difficulty when 

 used for barley in the summer time. At this season the reagents often have 

 temperatures far above 20° C, and this produces a cleavage of complexes hav- 

 ing a low rotation ; consequently the results obtained in the final calculation 

 are low. 



Sulphuric acid is not so well adapted for dissolving starch as hydrochloric 

 acid, and the results obtained with the latter are more constant. Tests were 

 made at the Brewing Experiment Station at Munich for the purpose of estab- 

 lishing whether under certain conditions values could be obtained which would 

 compare well with those given by hydrochloric acid. It was found that 

 aD=198° could only be obtained with sulphuric acid. 



Colorimetric determination of alcohols in the presence of ketones, H. 

 Agulhon {Ann. Chim. Analyt., 17 {1912), No. 2, pp. 50-5Jf; abs. in Chem. Ztg., 

 36 {1912), No. 39, Repert., p. 197). — These are color reactions with certain 

 organic substances, mineral acids, and potassium bichromate. 



The detection of formic acid in meat, O. Kapin {Ztschr. Fleisch u. Milchhyg., 

 22 {1912), No. 10, pp. 308-312). — Formic acid when added in small amounts to 

 meats goes into chemical combination with the protein and extractive sub- 

 stances but not with glycogen, and can only be detected with difficulty in the 

 distillate. In fact, this is often impossible in the concentration in which it is 

 used for preserving meats. 



With cosein practically ^11 the formic acid could be recovered, but egg 

 albumin, glue, and myosin (paramyosin) fixed large quantities of the sub- 

 stance. 



• Bui. Soc. Chim. France, 3. ser., 35 (1906), pp. 1285-1298. 



