708 EXPERIMENT STATION RECORD. 



with acids or ferments has undergone complete cleavage or not. If the hydroly- 

 sis is not complete the amount of bound peptids can be estimated. 



Detection of peptolytic ferments in animal and vegetable tissues, E. 

 Abderhalden (Ztschr. Physiol. Chem., 66 {1910), No. 3, pp. i37-i39).— The 

 author has previously drawn attention to the possible errors obtained with 

 Buchner's method (E. S. R., 23, p. 512) in the search for ferments. Two meth- 

 ods are described for the detection of peptolytic ferments, one being based on 

 the formation of tyrosin from silk peptone, and the other on the reaction 

 obtained for tryptophan where a polypeptid containing tryptophan is used, 

 respectively, glycyl-1-tryptophan. 



A new method for the quantitative estimation of hydrocyanic acid in 

 vegetable and animal tissues, A. D. Waller (Proc. Roy. iSoc. [London], 8cr. 

 B, 82 (1910), No. B 559, pp. 574-581, figs. 5). — The test is a colorimetric one 

 and is based on the fact that a red color is produced when sodium picrate 

 (picric acid and sodium carbonate) and hydrocyanic acid are brought together. 

 The color standards which are prepared with known amounts of sodium picrate 

 and hydrocyanic acid are very stable and not appreciably affected by sunlight 

 and boiling. 



The results of experiments as to the time relation of the electrical and chemi- 

 cal changfs taking place in anesthetized laurel leaves and the quantitative esti- 

 mation of hydrocyanic acid in the blood and tissues of animals and man after 

 death by hydrocyanic poisoning are given. 



Quantitative colorimetric determination of small amounts of hydrocyanic 

 acid, E. Berl and M. Delpy (Ber. Dent. Chem. Gesell., 43 {1910), No. 8, pp. 

 1J,30, 1J,31; abs. in Jour. Soc. Chem. Indus., 29 (1910), No. 13, p. S/.3).— The 

 method can be employed for quantities running from 4 to 0.04 mg. in 1 cc. of 

 liquid, and within a limit of error of 5 per cent. 



The solution to be examined is rendered slightly alkaline by a potassium 

 hydroxid solution (1:1). An oxidized solution of ferrous sulphate (1:30) 

 is added in the proportion of 2 molecules of ferrous sulphate to each mole- 

 cule of hydrocj-anic acid. The solution is allowed to stand at ordinary tem- 

 perature for 10 minutes, with frequent shaking, boiled for from 2 to 15 minutes 

 according to the amount of hydrocyanic acid, allowed to cool, and rendered 

 acid with 10 per cent hydrochloric acid. If at the expiration of 5 hours 

 the liquid is not colored, it should be made up to a bulk of 100 cc, shaken and 

 compared with a standard solution of hydrocyanic acid made up in the same 

 manner as the above. If, on the other hand, the liquid is colored it is carefully 

 poured off from the Prussian blue precipitate and distilled water added to take 

 its place. 



The determination of chlorophyll in plants, H. Malarski and L. March- 

 LEWSKi (Biochem. Ztschr., 24 (1910), No. 3-5, pp. 319-322; abs. in Zeatbl. 

 Physiol, 24 (1910), No. 9, p. 403). — The method consists of preparing a stand- 

 ard solution of chlorophyllan from the kind of plant to be examined and de- 

 termining its extinction coefficient in a chloroform solution. The chlorophyll of 

 the plant to be examined is then extracted and the extinction coefficient deter- 

 mined and compai'ed with the standard solution. 



About starch estimation methods, F. Schubert (Osterr. Vngar. Ztschr. 

 Zuckcrindus. u. Landw., 39 (1910), No. 3, pp. 411-422).— The author has modi- 

 fled Lintner's method (E. S. R., 20, p. lOOS) in so far that a measured amount of 

 water and acid is brought into the receptacle containing a weighed amount of 

 the starchy material filtered directly without washing out the measuring flask 

 or lining up to the graduation mark, and polarized at once. The phospho- 

 molybdic acid used for clarifying is contained in the water used for doughiug 



