TRANSACTIONS 01? THE SECTIONS. 37 



reason why a similar plan should not be earned out in this instance. The subject 

 is so serious, that its treatment ^^'ith reg-ard to disinfection ought not to be decided 

 by analogies between cattle plague and cholera, wliich are yet unproved. In a 

 visitation of this character it is possible to try experiments of a nature wholly out 

 of our power under ordinary' circumstances ; and thus it is feasible to suppose 

 that, from the lessons derived from this pestilence, we might obtain insight into the 

 laws governing zymotic diseases. 



Although foul sewage and putrefying animal matter are probably insufficient to 

 generate the first septic germ of a pestilence, there can be no question that when 

 such a plague does come amongst us, it spreads with the greatest virulence 

 wherever such putrescent materials abound. It may therefore be expected, not 

 imreasonably, that by extending the sphere of an operation of appropriate disin- 

 fectants, we may diminish the death-rate, and materially augment the well-being 

 of the community. 



On Ozone. Bij Dr. DAUBENy, F.R.S. 

 Dr. Daubeny communicated a summary of the observations and experiments he 

 had been making with respect to the presence of ozone in the atmosphere, the 

 sources from which it was derived, and its uses in the economy of nature. Judging 

 from the depth of coloration produced upon Schonbeiu's papers by exposure to 

 the open air, as observed dming a .period extending on the whole to eight months, 

 he inferred that the quantity of ozone at Torquay was much greater, on the average, 

 during the prevalence of winds proceeding fi-om the sea, than at times when they had 

 blown over land. By the same test he had endeavoured to ascertain wliethei- this 

 ozone was generated by vegetation ; and although he found that light alone exerted 

 some influence in colouring the paper, in proportion to its intensity, was led to infer 

 that, after deducting this, a certain residual effect was due to the action of the gi-een 

 parts of plants in generating ozone during the day ; and as ozone exercises an un- 

 doubted power in removing putrid matter by oxidation, it seemed probable that the 

 vegetable world may be thus the appointed means of destroying animal effluvia, 

 and of thus restoring to the atmosphere its original purity w hen vitiated by the 

 emanations of living beings. 



On the Refraction- and Dispersion-equivalents of Cldorine, Bromine, and 

 Iodine. By J. H. Gladstone, F.E.S. 



The refraction-equivalent of a substance is the product of its atomic weight into 

 its specific refractive energy, that is, its refractive index minus one divided by its 

 density. From data previously published by the author and the Eev. T. P. Dale, 

 together with Dulong s observations on gases, the following determinations of the 

 refraction-equivalents of the halogens had been made. 



Chlorine, as a gas, or in gaseous combination, gives the number 8'7 ; in the chlo- 

 ride of phosphorus it seems to be 9'4 ; while in several cases of its liquid com- 

 pounds of carbon and hydrogen it ranged from 9-6 to 10. 



Bromine, as the elementary liquid, gives the number 16-6; its liquid compound 

 with phosphorus indicates only 14'5, and its compounds with carbon and hydrogen 

 about 15 '5. 



Iodine, as determined fe'oni four liquid compounds of the iodide-of-methyl series, 

 averages 242. 



The numbers determined for bromine are nearly intermediate between those for 

 chlorine and iodine. 



The dispersion-equivalent of a substance is the difference between its refraction- 

 equivalents as calculated for the two extreme lines of the spectrum A and H. De- 

 terminations fi-om some of the same compounds of the halogens with methyl, ethyl, 

 &c., gave numbers, of which that for bromine lies also between those of the other 

 two, but considerably nearer to chlorine than to iodine. The following detennina- 

 tions are strictly comparable : — 



Chlorine. Bromine. Iodine. 



. Refi-action-equivalents 9 8 lo-5 24-2 



Dispersion-equivalents 0'5 1-3 2"6 



