Messrs. Wanklyn and Robinson on Diffusion of Vapours. 545 



Cobalt wire. 



X=12'930-0*03552U + 0*00004887£ 2 , 



corresponding to a percentage decrement of 23*692 per cent. 



Nickel wire. 



A = 12-222-0"040787* + 0-000. 7088* 2 , 



corresponding to a percentage decrement of 2 7' 5 73 per cent. 



Although these metals were said to be chemically pure, the results 

 obtained seem to indicate that they are not so, having probably taken 

 up some impurities in the process of fusion. 



The following Table of the conducting powers of pure metals 

 shows the place which the metals treated of in this paper take in the 

 series. 



Conducting power at 0°. 



Silver (hard drawn) 100-00 



Copper (hard drawn) 99*95 



Gold (hard drawn) 77*96 



Zinc 29*02 



Cadmium 23* 72 



Cobalt* 17*22 



Iron * (hard drawn) 16*81 



Nickel* 13*11 



Tin 12*36 



Thallium 9*16 



Lead 8*32 



Arsenic , 4*76 



Antimony 4*62 



Bismuth 1*245 



" On the Amyloid Substance of the Liver, and its ultimate desti- 

 nation in the Animal Economy." By Robert M c Donnell, M.D. 



March 19. — <c On Peculiar Appearances exhibited by Blood-cor- 

 puscles under the influence of Solutions of Magenta and Tannin." 

 }y William Roberts, M.D. 



" On Quinidine, and some Double Tartrates of the Organic Bases." 

 Jy John Stenhouse, LL.D., F.R.S. 



: March 26. — Major-General Sabine, President, in the Chair. 



1 The following communications were read : — 



! " On Diffusion of Vapours : a means of distinguishing between 

 apparent and real vapour- densities of Chemical Compounds." By 



"U. A. "Wanklyn and J. Robinson, Esq. 



The density of the vapour given off when a chemical compound 

 is heated is not necessarily the vapour-density of that chemical com- 

 pound ; sometimes it is only the mean density of the products of 

 decomposition. Some of the best-known substances, such as hydrated 

 sulphurous acid, ammoniacal salts, and pentachloride of phosphorus, 

 s v nir decomposition when they are vaporized, and thus have an 



* Probable value for the pure metal deduced from the observations with the 

 impure one. 



