510 SCIENTIFIC RECORD FOR 1882. 



phenol. 'Sow the mutual solubility of these liquids increases with the 

 temperature, and at a certain point {6S° for pure phenol) the two liquids 

 mix in all proportions. Many liquids, such as aniline and water, follow 

 the same law; solids, too, obey the same law, as is shown by the mutual 

 action of water and salicylic acid. The author claims that the solutions 

 of solid and of liquid salicj^lic acid exhibit a true physical isomerism. 

 {Bull. Soc. Chim., xxxviii, p. 145.) 



Molecular Structure and Physical Properties.— Th -At a close connection 

 exists between the structure of molecules and the physical properties 

 of the substances composed of these molecules is becoming more and 

 more evident. Pawlewski finds that the "critical temperatures" of 

 isomeric ethers are very nearly identical, and that isomers containing 

 doubly-linked atoms of carbon have a higher critical temperature than 

 those in the molecules of which the carbon atoms are singly linked. 

 (Berichte d. chem. Ges., xv, p. 460.) 



Determination of Gas Densities. — H. Goldschmidt and Victor Meyer 

 have devised a simple method for. determining gas densities in an expe- 

 ditious manner. The process was employed at first in connection with 

 ex])eriments made on the density of cyanogen at various temperatures, 

 but is applicable to many bodies. The vessel employed is first filled 

 with pure, dry air of the temperature at which the density is to be 

 taken ; the air is then displaced by hydrochloric acid gas (free from air), 

 collected over water and measured. The hydrochloric acid gas is in 

 turn replaced by air. The gas to be examined is then introduced until 

 all the air is expelled, and this gas is again displaced by hydrogen, or 

 by air, and collected in a potash bulb containing a liquid capable of 

 completely absorbing it. The increase in weight of the potash bulb 

 gives the weight of the gas ; the weight of an equal volume of air at the 

 same temperature is determined from the volume collected, and the 

 quotient gives the density sought. 



The apparatus consists of a glass cylinder 200™"" long, 30™™ in diam- 

 eter, with a capillary tube at each end, the extremities of which tubes 

 rise above the upper end of the cylinder and are bent at right angles. 

 This apparatus is heated in a glass tube witli a bulbous extremity 

 400"'™ long, and of sufficient size to contain the liquid, whose boiling 

 point is the temperature of measurement. The liquids used in the outer 

 vessel are water, aniline, amyl benzoate, and diphenylamine. For 

 higher temperatures boiling sulphur and penta-sulphide of phosphorus 

 are used, in which case the inner vessel receives a spherical form, and 

 the outer vessel is made of iron. 



The authors obtained by this process a density of 1.53 for carbonic 

 anhydride, and of 1.20 for hydrochloric acid gas, figures exactly equal 

 to the theoretical values. 



The apparatus can also be employed as an air thermometer. Sulphur 

 was found to boil at 426° C. {Berichte d. chem. Ges., xv, p. 137.) 



