Vapour-density of Bromine at High Tenvperatures. 489 



and introduced directly into liquid hydrogen contained in a vacuum 

 jacketed vessel immersed in liquid air. Under these conditions they 

 were exposed to a temperature of about - 252° C. (21° absolute) for 

 ten hours. At the end of the experiment the tubes were opened, and 

 the contents examined microscopically and by culture. The results 

 were entirely negative as regards any alteration in appearance or in 

 \'igour of growth of the micro-organisms. It would appear, therefore, 

 that an exposure of ten hours to a temperature of about - 252° C. has 

 no appreciable effect on the \dtality of micro-organisms. 



We hope to extend these observations upon the influence of the 

 temperature of liquid hydrogen on vital phenomena, and to make them 

 the subject of a future communication, and to discuss their bearing 

 upon problems of vitality. 



" Vapour-density ■ of Bromine at High Temperatures. — Supple- 

 mentary is^te." By E. P. Peemax, D.Sc, and a. A. S. 

 Atkixsox, B.Sc. Communicated by Professor Kamsay, F.Pt.S. 

 Pteceived April 28,— Eead May 31,*^ 1900. 



The authors regret that they had overlooked a monograph by C. 

 Langer and V. Meyer, entitled " Pyrochemische Untersuchungen," 

 containing an account of some experiments on the vapom--density of 

 bromine. Their method was to pass a mixture of bromine vapour 

 and nitrogen into a porcelain tube vdth. capillary ends placed in a 

 furnace in a horizontal position. The bromine and nitrogen were 

 then displaced by a current of carbon dioxide, the bromine being 

 absorbed by potassium iodide solution, and the carbon dioxide by 

 potash solution, while the nitrogen was collected and measiu-ed. 

 Temperatiu-e was ascertained by displacing the tube full of air in a 

 similar way. By this method Langer and Meyer carried out experi- 

 ments at " Zimmer-temperatur " 100°, 900°, and 1200°. 



The only results comparable with the authors' are those at 900°. 

 Their results at this temperature are 5-478, 5*414, 5-433, 5*382, 5*59, 

 mean 5-459 (air = 1), or 78*88 (H = 1). They say that these results 

 indicate that the mpour-density of bromine, even tchen diluted tuith eleven 

 times its volume of air, is still normal at 900°. 



The mean of our results at this temperature is 78-6, and the density 

 read from the curve (p. 17, vol. 66) is 78*8. This close agreement 

 shows that Langer and Meyer's results really indicate a small amount 

 of dissociation at 900°. Diminution of pressure appears to have little 

 effect at that temperature, as Langer and Meyer used bromine much 

 diluted with nitrogen, while in our experiments there was no decrease 

 of density on reducing the pressure from 767 mm. to 365 mm. 



It may be noted that Langer and Meyer give the boiling point of 



