306 Roifal Society. 



and in no way to the agency of the salts contained in it. The same 

 results are obtained when a simple solution oi' chlorine water is em- 

 ployed; but in that case the escape of the gas is considerable, and 

 consequently offensive to the operator and assistants. This is not 

 the case when the same quantity of chlorine is thrown into a solu- 

 tion of the two salts mentioned in the course of the paper; so that 

 Dr. Granville infers that the presence of those salts serves to lessen 

 the tendency of the free chlorine to escape in a gaseous form. When 

 the two salts, alone obtained by evaporation, are redissolved in di- 

 stilled water, no disinfecting effects are obtained, although so large 

 a proportion of the chlorine enters into their composition ; but if 

 two measures of that gas, equal to twice the bulk of the solution, 

 be thrown in, all the disinfecting properties are restored to the 

 liquid. 



Dr. Granville promises to lay before the Royal Society a con- 

 tinuation of his inquiries on this subject, in which he will describe the 

 mode of action of the disinfecting liquid on putrid animal matter, — 

 detail the new compounds that result from that action, — point out a 

 method of ascertaining the presence of animal effluvia in the air by 

 means of chlorine, applicable in time of infectious diseases ; and 

 lastly, suggest a more easy and oeconomical process of preparing 

 the Disinfecting liquid. 



A paper was also read, entitled " On the permeability of trans- 

 parent screens of extreme tenuity by radiant heat ; by W. Ritchie, 

 A.M." communicated by Mr. Herschel. 



Mr. Ritchie states that invisible radiant heat from sources at 

 elevated temperatures freely permeates thin transparent screens in 

 the same manner as light; but as this doctrine, established by Pro- 

 fessor Prevost and M. de la Roche, has been controverted, he 

 thinks it necessary to demonstrate it by fresh experiments. To 

 this end he covered a small aperture with a film of glass almost 

 iridescent, and keeping it constantly cold, by blowing on it, below 

 the temperature of the ambient air, he found that an air-thermo- 

 meter on one side of it was not affected by a heated iron ball on 

 the other, if the temperature of the ball was low; but that as the 

 temperature was raised, though not to the point of visible ignition, 

 the effect on the thermometer became sensible and even consider- 

 able. Several other experiments are adduced, confirmatory of the 

 same doctrine ; and the author finds that little difference of effect is 

 observed, whether the screens be near to or far from the heated 

 ball, ccEteris paribus: — and this he considers as demonstrating that 

 the effect was not due to secondary radiation from the screen. 



March 15. — Capt. G. Everest, the conductor of the Trigonome- 

 trical Survey of India, was admitted a Fellow of the Society ; and 

 MM, Struve, Stromeyer, Plana, and Soemmering, were respectively 

 elected Foreign members. 



A paper was read, entitled "Correction of an error in the reduc- 

 tion of the observatiotis for atmospherical refraction at PortBowen; 

 by Lieut. H. Foster, R.N. F.R.S." 



The reading was also commenced of a paper on Experiments for 

 determining the mean density of the earth, made, with two invariable 



pendulums, 



