328 



Capt. Abney and Col. Festing. 



[June 21, 



resulted in some compound which is a multiple of potassium ; potas- 

 sium being, as we know, an important constituent of normal muscle. 



Ba 137 x 2 = 274 274-Ca 40 = 234, 

 K 39x6= 234. 



Rubidium in large doses has the same effect as barium in causing a 

 veratria-like curve, but barium destroys the effect of rubidium before 

 producing its own effect. 



Rb 85-4x8 = 683-2, 

 Ba 137x 5 = 685. 



In the next division the authors show that by alternate application 

 of acids and alkalies the muscle of the frog may be made to describe 

 on a slowly-revolving cylinder curves which almost exactly resemble 

 those described on a quick cylinder by the normal contraction of a 

 muscle on stimulation ; and also those which the muscle describes on 

 irritation after it has been poisoned by barium. They consider that 

 the contraction of muscle may be possibly due in some measure 

 at least to alterations in acid or neutral salts which the muscle 

 contains. 



The lethal activity on frogs of the chlorides experimented upon is 

 as follows : the potassium being most powerful, and calcium least 

 powerful ; potassium, beryllium, rubidium, barium, ammonium, 

 caesium, lithium, lanthanum, didymium, erbium, strontium, yttrium, 

 sodium, calcium. 



VII. " The Influence of Water in the Atmosphere on the Solar 

 Spectrum and Solar Temperature." By Captain Abney, 

 R.E., F.R.S., and Colonel Festing, R.E. Communicated 

 at the request of the Committee on Solar Physics. Re- 

 ceived June 14, 1883. 



In our paper on " Atmospheric Absorption in the Infra-red of the 

 Solar Spectrum" (" Proc. Roy. Soc," vol. 35, p. 80), we stated 

 that the absorption by water coincided with the absorption bands 

 to be found in the solar spectrum, and our proof rested on photo- 

 graphs which had been taken for some time back. In the diagram 

 which we published (and in which are slight errors in shading 

 at some parts, and which we here correct) we showed the coinci- 

 dences as far as \10,000, that being the limit to which we could 

 accurately fix the wave-lengths. Simultaneously almost with the 

 publication of our paper, there came into our possession an account 

 of Professor Langley's researches on the solar spectrum, conducted by 

 means of the bolometer, a perusal of which determined us to vary 



