4-") 8 Prof. W. Beetz on the Molecular Changes 



has already shown the nullity of the action of mass when a very 

 weak acid is mixed with a very stable salt, — boric acid and sulphate 

 of potass. I have also shown that this action is nil even in the 

 decomposition of aqueous vapour by zinc, which is as easy as 

 that of oxide of zinc by hydrogen*. There only remain then 

 two capital experiments in which the influence of mass inter- 

 venes ; these are, on the one hand the decomposition of water by 

 iron and the reduction of oxide of iron by hydrogen, and on 

 the other, the inverse reactions of carbonic acid on sulphide of 

 potassium and of sulphuretted hydrogen on carbonate of potass. 



Without explaining the first phenomenon, I shall show that it 

 is too complicated to be completely accounted for by Berthollet's 

 hypothesis. For the other, that hypothesis is quite unnecessary. 

 Berthollet's law of the decomposition of salts sufficiently explains 

 it. For when a continued current of carbonic acid is passed into 

 solution of sulphide of potassium, a layer of carbonic acid forms 

 at the surface of the liquid, in which sulphuretted hydrogen is 

 volatile, while the dissolved carbonic acid acquires fixity. Hence 

 volatile sulphuretted hydrogen, fixed carbonic acid, and potass 

 are in presence of each other. By Berthollet's law sulphuretted 

 hydrogen would escape, and carbonate of potass be formed ; but 

 this decomposition would not take place without a continual 

 renewal in the composition of the atmosphere being produced 

 by a rapid current of carbonic acid ; and this explains why a 

 considerable excess of carbonic acid is needed to complete the 

 operation, and why the bubbles of sulphuretted hydrogen are 

 not visible in the liquid which is changed into carbonate at the 

 ordinary temperature. 



Changing the terms, the same reasoning applies to the inverse 

 decomposition of carbonate of potass by sulphuretted hydrogen. 

 But here, as the carbonic acid is less soluble in water than 

 sulphuretted hydrogen, it is disengaged more rapidly in an 

 atmosphere of sulphuretted hydrogen, and the decomposition of 

 carbonate of potass is more rapid than that of sulphide of 

 potassium. 



LXIII. On the Molecular Changes produced by Magnetization. 

 By W. Beetz t« 



THE molecular changes which take place when a bar of steel 

 or iron passes from the unmagnetic to the magnetic state, 

 may, as M. Weber J has shown, be regarded in four different 



* Annales de Chimie et de Physique, 3rd series, vol. xliii. p. 473 and 477 . 



t Translated from Poggendorff's Annalen, September 1860. 



X " Electrodynamische Maasbestimmungen, insbesonderc liber Diamag- 

 netismus," Abh. d. K. Sachs. Ges. d. IVissensch. phys. math. CI. 1852, i. 

 p. 541. 



