Separation of the Least Volatile Gases of Atmospheric Air,&c. 389 



Contrasted Effects of Methylbenzaconine and Benzaconine. 



Methylbenzaconine is from three to four times more toxic towards 

 rabbits and guinea-pigs than benzaconine, and from twice to thrice as 

 toxic towards frogs (R. temp, and R. esc). In mammals, slight saliva- 

 tion, retching movements, and muscular tremor are characteristic 

 effects of the former, but dyspnoea, ataxia, and paresis are also seen 

 after benzaconine. Of the two, methylbenzaconine is distinctly less 

 depressant towards the heart. Slowing of the pulse and want of 

 sequence of ventricular upon auricular action occurs after both, but is 

 a much earlier symptom after benzaconine, which causes more dis- 

 order in the motor mechanism. On the other hand, the intracardiac 

 vagus is put out of function more readily by methylbenzaconine. 

 Death after either poison is rarely preceded by spasm. Neither of the 

 two compounds cause any local irritation in frogs, but methylbenz- 

 aconine produces active fibrillation in the muscles, to which it gains 

 access and develops a complete curare-like action much more promi- 

 nently than does benzaconine, the heart continuing to beat strongly. 

 Benzaconine, in dose sufficient to cause such an effect at the periphery, 

 acts disastrously upon the circulation. In partial poisoning by 

 methylbenzaconine the characteristic rapid failure of the intramuscular 

 motor nerves on stimulation is well marked, but the subsequent 

 recovery on resting, so characteristic of benzaconine, has not been 

 observed. 



" On the Separation of the Least Volatile Gases of Atmospheric 

 Air, and their Spectra." By G. D. Liveing, M.A., Sc.D., 

 F.B.S, Professor of Chemistry in the University of Cam- 

 bridge, and James Dewar, M.A., LL.D., F.B.S., Jacksonian 

 Professor in the University of Cambridge, Fullerian Pro- 

 fessor of Chemistry, Koyal Institution, London. Eeceived 

 June 15,— Bead June 20, 1901. 



Our last communication to the Society* related to the most volatile 

 of the atmospheric gases, that which we now beg leave to offer relates 

 'to the least volatile of those gases. The former were obtained from 

 their solution in liquid air by fractional distillation at low pressure, 

 and separation of the condensible part of the distillate by cooling it in 

 liquid hydrogen. The latter were, in the first instance, obtained from 

 the residue of liquid air, after the distillation of the first fraction, by 

 allowing it to evaporate gradually at a temperature rising only very 

 slowly. The diagram, fig. 1, will make the former process intelligible. 



* ' Roy. Soc. Proc.,' vol. 67, p. 467. 



