and Electrolysis of Chemical Compounds. 381 



might, perhaps, be thought that this difficulty resulted from 

 the conditions of the experiment itself, the first-formed layer 

 of metallic chloride or the separated hydrogen adhering to the 

 metal in consequence of the high pressure (50-60 atmospheres) 

 and acting as a protecting film ; but Gore (I. c.) has established 

 other evidences of a feebler chemical activity — viz. that liquid 

 hydrochloric acid has no action on quicklime, acts but very 

 slowly on metallic oxides and carbonates, with the exception 

 of carbonate of calcium, and that liquid hydrofluoric acid acts 

 only on potassium and sodium, not on other metals, producing 

 a brisk liberation of hydrogen *. 



Lastly, the extremely slight solubility of the newly formed 

 substances in the liquid acids might, perhaps, have some in- 

 fluence ; they appear, even when dissolved, to diffuse very 

 slowly, and finally to settle at the bottom of the tube. In 

 favour of this idea may be alleged an experiment of mine, in 

 which calcium carbonate was decomposed by ordinary diluted 

 hydrochloric acid, even under a pressure of 50-60 atmo- 

 spheres ; here the water could immediately act as a solvent 

 on the calcium chloride formed. It is therefore very doubtful 

 if the difficulty of exchange of the hydrogen in the liquefied 

 gases depends on their special chemical character ; and hence 

 there is no substantial reason for connecting their feeble con- 

 ductivity with it. Besides, it is proved that a direct action 

 of the high pressure cannot have occasioned both phenomena. 

 The experiments of Favre, Berthelot, and Cailletet have shown 

 that even a pressure of 300 atmospheres does not directly in- 

 terfere with the chemical phenomena ; and the electrolysis of 

 water was observed by Gassiotf to take place even under a 

 pressure of 86 atmospheres. 



No important alteration was found by Herwig, recently, in 

 the conductivity of a solution of cupric sulphate under the 

 pressure of 18 atmospheres ; consequently there are no grounds 

 for attributing to the pressure in these cases any direct in- 

 fluence on the results. 



4. Electrolysis of Anhydrides. 



As a number of anhydrides possess no hydrogen in their 

 composition, they ought, according to the preceding hypo- 

 theses, to belong to the class of bad conductors. To test this 

 I selected only those which could be obtained in a high state 

 of purity and were fusible without decomposition. Hence 



* With, the hydrofluoric acid the pressure was not above one 

 atmosphere. 



t Jahresb.fiir Cliemie, 1854, p. 523. 



