310 EXPEErMENT STATION EBCOKD. 



acid content of muscle extracts prepared by boiling can be determined with 

 snfticient accuracj' by titration, using phenolpMhalein as the indicator. The 

 other acids present, which include small amounts of /3-oxy butyric acid, can be 

 neglected. The lactic acid retained by the coagulum can be determined by 

 liquefying the coagulum with potassium hydroxid solution, removing the alkali 

 albuminates, and determining the lactic acid in the filtrate according to the 

 V. Fiirth and Charnass method (potassium permanganate in a sulphuric acid 

 solution). 



On the accuracy of dry-matter determinations in root crops, R. K. Keis- 

 TENSEN (Tidsskr. Landbr. Planteavl, 19 {1912), No. 2, pp. 326-33Jf) .—By mak- 

 ing triplicate determinations, weighing out about 15 gm. of the pulp, and drying 

 directly, without addition of pumice stone or stirring with a glass rod, the 

 average error of analysis in from 252 to 420 samples amounted to 0.02G per 

 cent for mangels, 0.036 for ruta-bagas, 0.033 for turnips, and 0.03 for carrots. 



Detection of sucrose in grape juice and wines, S. Rothenfussee (Ztschr. 

 Untersuch. Nahr. u. Oenussmtl., 2Jt {1912). No. 1-2, pp. 93-104; abs. in Jour. Soc. 

 Chem. Indus., 31 {1912), No. 16, pp. 789, 790).— In grape juice, 5 cc. of the juice 

 is added to a solution of 6 gm. of barium hydroxid in 25 cc. of water to which 

 has been added 25 cc. of a 3 per cent solution of hydrogen peroxid. The 

 mixture, contained in a glass or nickel basin, is heated on a water bath for 

 20 minutes and if, during heating, a yellow color is developed, hydrogen 

 peroxid solution is added drop by drop until the color is destroyed. The liquid 

 is filtered and 5 cc. of the filtrate is heated in a boiling water bath with an 

 equal volume of the diphenylamin reagent (a solution prepared by adding 

 20 cc. of a 10 per cent alcoholic solution of diphenylamin to 60 cc. of glacial 

 acetic acid and 120 cc. of concentrated hydrochloric acid). In from 7 to 8 

 minutes a strong blue color is developed if only from 0.1 to 0.2 per cent of 

 sucrose is present in the original juice. After more prolonged he;\ting, some 

 juices, known to be free from sucrose, give a slight coloration, but this can not 

 be mistaken for the color developed when sucrose is present. 



" Dry wines : — Ten cc. of the wine is added to 50 cc. of a 5 per cent barium 

 hydroxid solution which has been mixed with 10 cc. of a 3 per cent hydrogen 

 peroxid solution, and the test is proceeded with as described for grape juice. 

 It is not necessary to remove the color of red wines, as this is destroyed ia 

 carrying out the test, and if the wine is unusually acid it can be neutralized 

 by using a suflicient excess of barium hydroxid solution. 



" Sweet wines : — Ten cc. of the wine is shaken with 50 cc. of acetone and the 

 cloudy solution is filtered, a pinch of purified kieselguhr having been added to 

 assist clarification. Thirty cc. of the filtrate is mixed with 30 cc. of water, 

 and the mixture is heated on a water bath until the acetone has been driven 

 off. Six gm. of barium hydroxid and 25 cc. of a 3 per cent hydrogen peroxid 

 solution are added, and the whole stirred until the barium hydroxid is dis- 

 solved. If a yellow color is developed it is removed by small additions of 

 hydrogen peroxid and after heating for 20 minutes the liquid is filtered. 

 Five cc. of the filtrate is shaken with 5 cc. of dilute sulphuric acid and 5 cc. 

 of the diphenylamin reagent, and the mixture heated for S minutes in a boiling 

 water bath. On allowing the separated barium sulphate to settle, the clear 

 liquid will be of a strong blue color if sucrose is present. As almost all sweet 

 wines, from a cause which has not yet been investigated, give a weak coloration, 

 equal to that produced by from 0.02 to 0.1 per cent of sucrose, such weak 

 indications must be neglected." 



The behavior of the peroxidase of cow's milk during the process of heat- 

 ing, J. J. Van Eck {Chcm. WeelcM., 8 {1911), No. 37, pp. 691-702, figs. 2).— 



