Mr Graham on the absorption of' Vapours by Liquids. 



The use of them was therefore discontinued, and hemispheres 

 or capsules of glass three inches in diameter, and blown as 

 like each other as possible, were employed in their place. 



1. Solutions were formed of one part chloride of sodium in 

 four parts water, and of anhydrous carbonate of potash and 

 -water in the same proportions. The carbonate of potash, 

 which is deliquescent, was obtained by keeping the sesqui- 

 carbonate in a red heat till the excess of acid and the water 

 which it contains were wholly expelled. Three of the glass 

 capsules were placed in contact on the wire-cloth support of 

 a small tin canister, with water below, but not in contact with 

 them. These capsules contained respectively, 500 grains water, 

 500 grains of the solution of chloride of sodium, and 500 

 grains of the solution of carbonate of potash. They were 

 less than half full. The observation being made that no in- 

 equality of temperature existed within the canister, its lid was 

 applied, and the joinings made air-tight with lard. Upon 

 examination at the expiration of six days, the capsule of water 

 was found to have lost 23 grains ; that of the solution of 

 chloride of sodium to have gained 39 grains ; and the solution 

 of carbonate of potash was found to have gained only 6.5 

 grains. Here it is evident that the solution of chloride of so- 

 dium had drawn vapour not only from the water below, but 

 likewise to a large extent from the adjoining capsule of water, 

 and most probably to a small extent from the solution of car- 

 bonate of potash, likewise in contact with it. The solution of 

 chloride of sodium appears, therefore, to possess a manifest 

 superiority in absorbing power over a similar solution of 

 the deliquescent carbonate of potash. 



S. In a large tin-canister or box, eighteen inches long, nine 

 broad, and four deep, with a wire-cloth support and water 

 under it, precisely as in the foregoing case, ten capsules con- 

 taining various solutions were arranged at the same time. To 

 prevent the liquids from influencing each other, they were 

 separated by temporary screens of pasteboard, so that each 

 capsule was contained in a cell by itself; but all communi- 

 cated equally, through the apertures of the wire-cloth, with 

 the reservoir of water below. The results of this experi- 

 ment are thrown into the form of a table. In the first 



