130 



Mr. H. Lamb. 



[Apr. 5, 



radiation carbonic acid is one of the most transparent of gases ; for 

 the radiation from the hot carbonic acid prodnced in the carbonic 

 oxide flame, it is the most opaque of all. 



Again, for all ordiuary sources of radiant heat, bisulphide of carbon, 

 both in the liquid and vaporous form, is one of the most diathermanous 

 bodies known. I thought it worth while to try whether a body re- 

 puted to be analogous to carbonic acid, and, like it, so pervious to most 

 kinds of heat, would show any change of deportment when presented 

 to the radiation from hot carbonic acid. Does the analogy between 

 the two substances extend to the vibrating periods of their atoms ? 

 If it does, then the bisulphide, like the carbonic acid, will abandon its 

 usually transparent character, and play the part of an opaque bady, 

 when presented to the radiation from the carbonic oxide flame. This 

 proves to be the case. Of the radiation from hydrogen, a thin layer 

 of bisulphide transmits 90 per cent., absorbing only 10. For the 

 radiation from carbonic acid, the same layer of bisulphide transmits 

 only 25 per cent., 75 per cent, being absorbed. For this source of 

 rays, indeed, the bisulphide transcends, as an absorbent, many sub- 

 stances which, for all other sources, far transcend it.* 



II. " On Electrical Motions in a Spherical Conductor." By 

 Horace Lamb, M.A., formerly Fellow of Trinity College, 

 Cambridge, Professor of Mathematics in the University of 

 Adelaide. Communicated by J. W. L. Glaisher, M.A., 

 F.R.S. Received March 14, 1883. 



(Abstract.) 



This paper treats of the motions of electricity produced in a 

 spherical conductor by any electric or magnetic operations outside it. 

 The investigation was undertaken some time ago in illustration of 

 Maxwell's theory of electricity. This theory is so remarkable, more 

 especially in the part which it assigns to dielectric media in the 

 propagation of electro-magnetic effects, that it seemed worth while to 

 attack some problem in which all the details of the electrical pro- 

 cesses could be submitted to calculation, although it was evident 



* Nearly twenty years ago I observed, among other changes of diathermic position, 

 the reversal of bisulphide of carbon and chloroform, when the pale blue flame of a 

 Bunsen burner was the source of heat. When, for example, the rays issued from a 

 luminous jet of gas, the absorptions of the bisulphide and of chloroform were found to 

 be 9 '8 and 12 per cent, respectively ; whereas when the Bunsen flame was employed, 

 the absorptions of the same two substances were ll'l and 62 per cent. The cause 

 of thi9 reversal doubtless is that in the Bunsen flame hot carbonic acid is the prin- 

 cipal radiant. (" Phil. Trans.," 1864, p. 352.)— April 6. 



