EXPERIMENTS OF GASES ABSORBED BY WATER.* 231 



furnifhed with a cock b. B is a glafs tube, of about \ inch 

 bore, bent at a right angle, and graduated, from a given point, 

 into hundredth parts of a cubical inch. It is attached to the 

 copper pipe, by a tube of Indian rubber D, over which is a 

 covering of leather, forming a joint, which admits of the veflel 

 A being brilkly agitated. When the apparatus is ufed, it is 

 firft filled with quickfilver; a transfer bottle of elaftic gum, 

 furnifhed with a cock, and containing water of a known tem- 

 perature, is fcrewed on ; and a communication is opened, 

 through the cocks, between the bottle and the glafs veflel. 

 The lower cock b is then opened, through which the mercury 

 runs out, while its place is fupplied by a quantity of water 

 from above, meafurable by the fcale on A. This transfer is 

 removed, and another containing gas being fubftituted, a mea- 

 fured quantity of gas is admitted in a fimilar manner. Strong 

 agitation is now applied, by means of the joint D ; and mer- 

 cury is poured into the tube B, to fupply the defcent occa- 

 fioned by the abforption in A j its level being exactly pre- 

 ferved in both legs of the fyphon, both at the commencement 

 and clofe of the experiment. The quantity of mercury re- 

 quired for this purpofe, indicates precifely the amount of the 

 gas abforbed. 



The only advantage of this apparatus over a cylindrical jar, 

 inverted in the ufual way over mercury, is, that by means of 

 the tube B, very minute degrees of abforption may be mea- 

 fured, which would fcarcely be perceived in a wide veflel. 



For the more abforbable gafes, I found this inflrument to Another appa-r 

 anfwer perfectly well, but, for afcertaining the folubility of J*™ L^^-* 

 thofe which are taken up by water in only fmall proportion, I forbed by wat«r. 

 preferred one of different conftru&ion. It confifted fimply of 

 a glafs veflel, of the capacity of 57 \ cubical inches, and fliaped 

 as in Fig. 2. At a was cemented a cock, provided with a 

 fcrew ; and the lower cock b was of glafs, accurately ground 

 in. The veflel was then filled with water which had been 

 long boiled ; a lifting valve was fcrewed on a, the cock being 

 open, and the veflel was placed under the receiver of an air 

 pump, where it was kept for fome time, the pump being oc- 

 cafionaily worked, as long as any air bubbles could be feen to 

 arife. The gas under examination was next admitted from an 

 elaftic bottle, the cock b being opened, and a meat'ured quan- 

 tity of water let out. The gas and water were then violently 



agitated 



