Chemistry and Physics. 385 



ordinary temperatures, provided a closed space be employed such 

 as the author describes. Experiments with naphthalene and 

 picric acid, acetanilide and benzil, and the isomeric diacetyl-com- 

 pounds of /?-diphenylglyoxime are described in the paper. — Ber. 

 Berl. Chew.. Ges., xxi, 701, 784, 860, 1068, March, April, 1888. 

 J. Chem. Soc, liv, 408, 597, May, June, 1888. g. f. b. 



3. On the Vapor-density of Hydrofluoric acid. — Thorpe and 

 Hambly have published a preliminary note on the vapor-density 

 of hydrogen fluoride. The object of their experiments was to 

 ascertain whether this gas possesses a constitution agreeing with 

 the formula H 2 F 2 , assigned to it by Mallet from its density at 

 30-5°, through any considerable range of temperature. By 

 means of a large platinum apparatus provided with stopcocks of 

 the same metal the vapor density of hydrogen fluoride was de- 

 termined at temperatures varying from 26*4° to 88'3°. The ma- 

 terial was prepared pure as required for each experiment, from 

 acid potassium fluoride, and was then redistilled through the 

 platinum apparatus placed in a bath of glycerin. Fourteen ex- 

 periments at short intervals -between the limits of temperature 

 given, afforded values corresponding to molecular weights rang- 

 ing from 51*19 at 26*4° to 20'58 at 88'3°. It appears therefore 

 that there is in this case a gradual and progressive breaking 

 down of a complex molecular grouping, analogous to that ob- 

 served in the case of acetic acid. — J. Chem. #oc.,liii, 765, August, 



1888. G. F. B. 



4. On the Spectrum of Oxygen. — Janssen, in his observations 

 on the Pic du Midi, has shown that the indistinct bands in the 

 spectrum of oxygen become visible in the solar spectrum when 

 the layer of the atmosphere through which the sun's light passes 

 is sufficiently large. He has confirmed the existence of these 

 bands and has proved, by a series of observations ranging from 

 atmospheric pressure to a pressure of 100 atmospheres, with tubes 

 varying from 0"42 to 60 meters in length, the law that the intens- 

 ity of these bands is proportionate to the product of the diameter 

 of the layer of oxygen into the square of the density of the gas. 

 Janssen has calculated that the bands should be just visible with 

 a layer of liquid oxygen four or five millimeters in thickness; 

 and the result of the calculation has been verified by Olzewski 

 who has experimentally observed them in a layer seven milli- 

 meters thick. — C. B., cvi, 1118, April, 1888. g. f. b. 



5. On the Valence of Oxygen. — In order to avoid the high 

 valence of the haloids, on the one hand, in their oxygen acids, and 

 on the other, the long and fragile atomic chain, Heyes has sug- 

 gested that oxygen should be considered as quadrivalent, the 

 haloids themselves being trivalent. Thus written potassium hypo- 

 chlorite becomes K— C1 = = = C1 — K ; and the chlorate and 

 perchlorate are to be viewed as formed of the group K — 01 = 

 joined to groups of oxygen atoms (0 3 )" or (0 4 )", in such a way 

 perhaps as to form a closed chain. Moreover the author believes 



Am. Jour. Sci.— Third Series, Yol XXX Vr, No. 215.— Not., 1888. 

 24a 



