948 EXPERIMENT STATION RECORD. 



Coudon ( E. S. R., 15, p. 850) depending upon the relation of the water-soluble and 

 insoluble volatile fatty acids was applied by the author to mixtures of known com- 

 position and to 11 commercial samples with satisfactory results. 



On the specific rotation of salts of casein, J. H. Long (Jour. Amer. Ghent. Soc, 

 27(1905), No. 4, pp- 863-366) . — Casein was prepared from diluted separator skim 

 milk by precipitation with acetic acid, repeated washing by decantation with dis- 

 tilled water, and dissolving in weak sodium hydroxid. After repeating this process 

 several times the precipitate was washed with alcohol and ether and the residue 

 dried over sulphuric acid. Determinations at 20° were made of the specific rotation 

 of sodium, potassium, lithium, and ammonium compounds of casein. The values 

 obtained were higher than those previously reported. In all cases the specific 

 rotation was increased with increase of alkali. 



Chemical studies of Tunis olive oil, E. Milmau (Seifensieder Ztg., 31 (1904), 

 pp. 77, 78, 98, 99, 118, 119, 135, 159, 183; abs. in Ztschr. Untersuch. Nahr. it. GenussmU., 

 8 (1904), No. 9, pp. 5S6, 587). — The composition of Tunis olive oil and related ques- 

 tions are the subjects taken up by the author. 



Quantitative determination of pentosans and methyl pentosans in natural 

 products, W. B. Ellett (Inaug. Diss., Univ. Gottingen, 1904, pp.50; abs. in Jour. 

 Landw., 53 (1905), No. 1, pp. 13-25). — The purpose of the investigations reported 

 was to devise a method for the simultaneous determination of methyl pentosans and 

 pentosans in vegetable products. Votocek's statement was confirmed that methyl- 

 furfurol-phloro-glucid in distinction from furfurol-phloro-glucid, even when dried, is 

 soluble in alcohol. It seemed probable, therefore, that the methyl-furfurol-phloro- 

 glucid and the furfurol-phloro-glucid could be weighed together; the methyl-furfurol- 

 phloro-glucid removed with alcohol; and the furfurol-phloro-glucid remaining 

 weighed, the difference between the two weighings, of course, giving the quantity of 

 methyl-furfurol-phloro-glucid. Details of the method outlined were elaborated and 

 a number of tests showed that it was satisfactory. Formulas were devised designed 

 to simplify the method of calculation, and a table which showed the amount of 

 methyl pentose, i. e., rhamnose, corresponding to 0.010 gin. to 0.149 gm. of phloro- 

 glucid. The author states that rhamnose is the only methyl pentose with which he 

 was able to experiment, but that possibly other pentoses would differ in the amount 

 of methyl-furfurol which they would produce. 



In addition to the above, studies were made of the methyl pentosans or methyl 

 pentoses obtained by hydrolysis of pomegranate and white pepper. From green 

 pomegranate rhamnose was isolated, which explains the formation of methyl furfurol 

 by distillation of pomegranate, hi the case of white pepper the author did not 

 succeed in isolating the mother substance of furfurol and methyl furfurol. Studies 

 with tetrose were undertaken to find a typical reaction for this group. 



On the distribution of potassium in animal and vegetable cells, A. B. 

 Macallum (Jour. Physiol, 32 (1905), No. 2, pp. 95-128, pis. 2).— Specially prepared 

 hexanitrite of cobalt and sodium was used in the experiments reported as a precipi- 

 tant for potassium. When the reagent is prepared by dissolving 20 gm. cobalt nitrite 

 and 35 gm. sodium nitrite in 75 cc. of water, adding thereto 10 cc. of glacial acetic 

 acid and diluting with water to 100 cc, it precipitates instantaneously and completely, 

 according to the author, all the potassium from its solutions as the triple salt. After 

 treating cellular elements and fresh tissues with the reagent they must be thoroughly 

 washed with ice-cold water to remove all traces of the precipitant. The triple salt 

 will be left behind and if abundant may be detected under the microscope by its 

 light yellow color. The presence and distribution of minute quantities may In- 

 detected by treating with ammonium-sulphid solution which gives a black coloration 

 due to cobaltous sulphid reaction wherever triple salt is precipitated. Some of the 

 author's conclusions follow: 



