10 Sir James Hall on the Consolidation of the Strata. 



ciently saturated with salt by the discharge of the fresh-water ; and I 

 thought it much easier, and no less satisfactory, to employ brine from the 

 first, formed at once by loading the water with as much salt as it could 

 dissolve, amounting to about one-third of its weight. 



" The vessels employed in these early experiments, were the large black- 

 lead crucibles used by the brass-founders. I filled the vessel, which was 

 18 inches high and 10 broad, nearly to the brim with brine of full satura- 

 tion, the lower portion being occupied, to the depth of about 15 inches, 

 with loose sand from the sea-shore, and thoroughly drenched with the 

 brine. In order to have a view of the progress of the experiment, I placed 

 an earthen-ware tube, about the size and shape of a gun-barrel, closed at 

 bottom, and open at the top, in a vertical position, having its lower extre- 

 mity immersed in the sand, and reaching to within about an inch of the 

 bottom of the pot, while the other end rose a foot above the surface of the 

 brine, and could be looked into without inconvenience. 



" After a great number of experiments, furnishing an unbounded va- 

 riety of results, 1 at length obtained a confirmation of the main object in 

 view. I observed that the bottom of the porcelain barrel, and of course 

 the sand in which it rested, became red-hot, whilst the brine, which, dur- 

 ing the experiment, had been constantly replenished from a separate ves- 

 sel, continued merely in a state of ebullition : the upper portion of the 

 sand, drenched with the liquid, remained permanently quite loose, but the 

 lower portion of the sand had formed itself into a solid cake. 



" On allowing the whole to cool, after it ha<l been exposed to a high 

 heat for many hours, and breaking up the mass, I was delighted to find 

 the result, occupying the lower part of the pot, possessed of all the quali- 

 ties of a perfect sandstone, as may be seen in the specimens now presented 

 to the Society. Whenever the heat was not maintained so long, the sand- 

 stone which resulted was less perfect in its structure, tasted strongly of 

 salt, and sometimes crumbled to sand when placed in water. 



" Many of these early experiments were accomplished with tolerable 

 success. But still the result was somewhat precarious, and could not be 

 announced with the confidence that I felt in presenting my former experi- 

 ments to this Society. 



" The cause of this uncertainty I traced to the chemical operation of 

 the salt, acting as a flux upon the porcelain vessels employed. This very- 

 action, I was well aware, was the main agent and cause of our success, 

 when kept within proper bounds ; but, on being allowed to pass those li- 

 mits, and to act on the containing vessel as well as on the experiment, it 

 destroyed the vessel, and converted the whole into a confused mass of slag. 



" After numberless unsuccessful attempts, and after returning again 

 and again to the charge, with an interval sometimes of years, I at last met 

 with a quality in some of the materials to me altogether unlooked for, by 

 means of which may be obtained successful results, with scarcely any risk 

 of failure. 



" I found that the action of the salt upon the substances of the crucibles 



4 



