CHEMISTRY. 291 



by their new method, the chlorine being j)roduced by dropping platinous 

 chloride into the tube heated to 1200°, have found that at these high 

 temi^eratures this gas has a density only two-thirds of that correspond- 

 ing to the molecule CI2. Subsequently Crafts repeated the determination , 

 using already-prepared chlorine, and found its density to be normal; a 

 result confirmed by Victor Meyer, working in conjunction with Ziiblin. 

 To reconcile these facts it seems to be necessary to admit that while 

 free chlorine is stable at high temperatures, nascent chlorine is not, but 

 undergoes dissociation into products not yet known. The results, how- 

 ever, obtained by the German chemists with iodine, which showed the 

 same anomaly, were fully confirmed by Crafts. Its vapor has at 1570° 

 two-thirds of its normal density. Bromine is intermediate, its vapor 

 density being reduced only one-fifth at high temperatures, when the 

 bromine was free, and one-third when it was nascent. — {Ber. Berl. Chem. 

 Ges., xii, 1426, 20GC, 2202, 2204, 1879; xiii, 394, 399, 401, 405, 851, 1050, 

 1103, 1880; a R., xc, 183, 690; xci, 54; Nature, xxi, 461, March, 1880; 

 Am. J. ScL, III, xviii, 222, 1879.) 



Oftret has revised the calculations of Pictet by which he reached a 

 density of 0.9883 and 0.9787 for liquefied oxygen, and has shown errors 

 in them by which the density is reduced to 0.8655 ; a result close to 

 0.8402, which the author obtains by a diflerent process of computation. 

 —{Ann. Ghim. Phys., Y, xix, 271, February, 1880.) 



Berthelot has published a work in two volumes, entitled "Essai de 

 m^canique chimique fondee sur la Thermochimie." One of the laws it 

 establishes is the following: "Every chemical change effected without 

 the aid of foreign energ}^ tends toward the production of those bodies or 

 of that system of bodies which evolves the most heat." Thus he shows 

 that for the metals K, Na, Ca, Sr, Mg, Mn, Fe" Zn, Cd, Pb, (Ca,)" 

 Hg," Ag and (Alz)"^', less heat results from the formation of oxides, than 

 from the formation of chlorides. Hence gaseous chlorine should decom- 

 pose these oxides, producing chlorides and evolving oxygen. This, in 

 fact, actually takes place provided the reaction is initiated by suitably 

 raising the temperature. — {J. Phys., viii, 402, December, 1879.) 



INORGANIC. 



Dumas has studied the property of occluding hydrogen possessed by 

 certain metals, and finds that aluminum may occlude as much as one 

 and a half times its volume of this gas, as well as traces of carbon 

 dioxide. These gases were given out again when the metal was heated 

 to redness in an exhausted tube. Magnesium exhibits a similar be- 

 havior; so that to obtain these metals pure, they should be distilled in 

 vacuo. These observations may throw some light on the anomalous 

 behavior of aluminum when used as an electrode in the voltameter. — 

 {Nature, xxii, 89, May, 1880.) 



Morley has made a series of careful analyses of air in order to ascer- 

 tain the limits of the variation of the oxygen in a single locality. On 



