1865.] Liquefied Hydrochloric Acid Gas. 213 



arise in a great measure from its feeble solvent capacity insoluble films 

 forming upon the surface of the bodies immersed in it preventing its con- 

 tinued contact and further action. This want of contact could hardly 

 have been the case in the remarkable instance of caustic lime : here was a 

 powerful and true acid (i. e. a hydrogen acid) and a powerful base; each in 

 a nearly pure state ; both possessing under ordinary circumstances a very 

 powerful chemical affinity for each other ; the one a liquid, and the other 

 a porous solid ; brought into intimate contact by an enormous pressure 

 forcing the liquid into the porous solid ; the solid base being very small 

 in bulk, and the liquid acid largely in excess, probably fifty times the 

 quantity necessary for its saturation ; and the action extended over a far 

 greater period of time than would in the presence of water been at all ne- 

 cessary : nevertheless no perceptible chemical action occurred ; the two 

 remained totally uncombined. 



It must not be overlooked that the results are partly due to anhydrous 

 hydrochloric acid in the liquid state, and partly to the same acid in the 

 gaseous state, under great pressure, the one class of effects not being 

 eliminated from the other in the present experiments ; it is probable that 

 if the substances could have been submitted to the action of the liquid 

 acid alone, the chemical effects would have been much smaller even than 

 they were. For instance, the action upon potassium, sodium, and tin ap- 

 peared to be due to the influence of the acid in the gaseous state, as no 

 gas was perceptibly evolved by these metals in the liquid acid. In the 

 cases of potassium and sodium (the latter in particular) it is perhaps pos- 

 sible, though highly improbable, that the whole of the metal had been 

 corroded before the liquid acid touched it ; but with tin this was certainly 

 not the case, some metallic tin being left uncorroded at the end of the 

 experiment. 



Oxides in general, with the exception of lime and certain others which do 

 not readily combine with aqueous hydrochloric acid, were slowly converted 

 in a greater or less degree into chlorides. Carbonates also, except that of 

 lime, were in general converted in a greater or less degree into chlorides. 



Such carbonates as were decomposed evolved no visible bubbles of gas in 

 the liquid acid : this may be explained on the supposition that they were 

 previously completely decomposed by the (/aseous acid during the process 

 of generation (this, however, was not the case with carbonate of soda), or 

 that the liberated carbonic acid was in the liquid state and was dissolved 

 by the liquid hydrochloric acid. In my former paper it was shown that 

 liquid carbonic and hydrochloric acids generated and condensed together 

 did not form two separate strata of liquid. 



Sulphides were in some cases converted into chlorides ; in other cases 

 not so ; in nearly all cases a trace of whitish sublimate was produced in the 

 (j aseous acid. The chlorate and nitrate of potash were both decomposed. 



I may here take the opportunity of stating that tubes charged with liquid 

 carbonic acid in October 1860 suffered no leakage by February 1865. 



