TRANSACTIONS OF THE SECTIONS. 



71 



acid, — an action which indicated no decomposition of the real acid, 

 but such as implied the presence of water, or a hydrous acid. A table 

 of the elastic force or tension of the gas, over the liquid carbonic acid, 

 was shown, for each ten degrees of the thermometer, beginning at 

 zero, and terminating with 150 degrees. The following are some of 

 the results : — 



_ Mr. Addams announced his intention of examining the pressure at 

 higher temperatures, up to that of boiling water, and above ; and as- 

 serted his belief that carbonic acid may be profitably employed as an 

 agent of motion — a substitute for steam, — not directly, as had been 

 already tried by Mr. Brunei, but indirectly, and as a means to circulate 

 or reciprocate other fluids. The solidification of the acid Avas shown, 

 and the freezing of pounds of mercury in a few minutes, by the cooling 

 influence which the solid acid exercises in passing again to the gaseous 

 state. 



On a New Process for Tanning. By William Herapath. 



The author, after noticing the impediments to a perfect accomplish- 

 ment of the three great objects of the tanner, viz. to make the skins of 

 animals iiisoluble, imputrescible, and impermeable to water, describes a 

 new process, by which these objects are accomplished at a less cost 

 than that of the old methods. In the ordinary process, the harder 

 fibres of the skin are perfectly tanned ; but the gelatine, which, if re- 

 tained, would be of the greatest value in rendering leather imperme- 

 able to water, disappears from the product, or is seen as an injurious 

 yellow coat on the surface. In reasoning on the difficulties experienced 

 by tanners, Mr. Herapath was brought to the conclusion that they were 

 occasioned by the force of capillary attraction ; and finding that the or- 

 dinary modes of 3i]ip\png pressure, handliuff, &c. were expensive and in- 

 sufficieut, he determined to try the effect of rolling the hides, connected 

 together as an endless band. 



" If I wish to tan one hundred hides a week, I should have eight pits, 

 over each of which would be affixed a pair of rollers ; the upper ones 

 to be loaded by weights fixed on their levers. For each pit fifty hides 

 or butts would be made into an endless band by ligatures of twine ; 

 upon introducing each band between a pair of rollers, each hide would 

 be in succession pulled from the bottom of the pit, squeezed by the 



