72 Scientific Intelligence. 



a one-third normal solution of potassium ferrocyanide. The 

 author proposes a modification of Pfeffer's method of determining 

 osmotic pressure. It is based on the fact that if two solutions 

 having different osmotic pressures be placed on opposite sides of 

 a semi-permeable membrane, water will flow through the mem- 

 brane into the solution whose osmotic pressure is the higher ; so 

 that by applying external pressure till balance is attained, the 

 differential osmotic pressure is determined. The apparatus used 

 is figured in the paper. — Zeitschr. physikal. Chem., ix, 97, Feb., 

 1892. G. F. B. 



3. On the Coefficient of Molecular Depression of Phenol. — 

 Two numbers have been given for the molecular depression-con- 

 stant of phenol ; one by Raoult, obtained with phenol of a melt- 

 ing point 37*8°, by means of naphthalene, camphor, benzoic acid 

 and thymol, which has the value 67'5; the other by Eykmann, 

 which is 76. Juillard and Cttrchod, using a synthetically pre- 

 pared specimen of phenol having a melting point 41-2°, find that 

 the molecular depression-constant varies with the dissolved sub- 

 stance. Thus for example for water, /3-naphthol, paratoluidine, 

 aniline, nitrobenzene, phthalic anhydride, diphenic anhydride, a- 

 naphthylamine, amyl alcohol, licinic acid and salol, they get the 

 value 68'5; while for normal ethereal salts, especially those of 

 dibasic acids such as methyl diphthalate, ethyl succino-succinate, 

 ethyl malonate, ethyl succinate, ethyl aceto-acetate, the value ob- 

 tained is 75-81. In their experiments the amount of depression was 

 determined in a long-necked thick glass flask of 40-50 cc capacity, 

 by noting the solidifying point of the phenol after the addition 

 of the other substance. — Bull. Soc. Ghent., Ill, vi, 237 ; J. Chem. 

 Soc, Ixii, 555, May, 1892. g. f. b. 



4. On the determination of Vapor Density under Diminished 

 Pressure. — Schall has devised a method of determining the 

 density of a vapor under .diminished pressure, based on the fact 

 that when gas is evolved in a bulb uniformly heated, this bulb 

 being provided with a manometer, the increase of pressure is 

 independent of the point at which the gas is evolved and is 

 exactly proportional to the amount of gas or vapor produced, 

 provided the space shut-off by the manometer may be considered 

 constant. It is a modification of the method already described 

 in this Journal.* The bulb used is moderately thick, of about 

 150 cc capacity, having two constrictions equidistant in its length 

 to hinder the diffusion of the vapor into the neck, and provided 

 with a lateral tube connected with a manometer, and interme- 

 diately with a bell jar for the evolution of carbon dioxide. For 

 the method of using it and the calculation we must refer to the 

 original paper. — J. prakt. Ch., II, xlv, 134, 1892. g. f. b. 



5. Jahrouch der Chemie. Bericht tiber die wichtigsten Fort- 

 schritte der reinen und angewandten Ghemie, herausgegeben von 

 Richard Meter, Braunschweig. I Jahrgang, 1891. 544 pp., 

 8vo. Frankfurt a. M., 1892 (H. Bechhold). — This new Jahrbuch 



*This Journal, III, xl, 415, November, 1690. 



