192 Mr. J. Y. Buchanan on the Absorption of [Feb. 19, 



February 19, 1874. 

 JOSEPH DALTON HOOKER, C.B., President, in the Chair. 



The Presents received were laid on the Table, and thanks ordered for 

 them. 



The following Papers were read : 



I. " On the Absorption of Carbonic Acid by Saline Solutions." 

 By J. Y. BUCHANAN, Chemist on board H.M.S. ' Challenger/ 

 Communicated by Prof. WILLIAMSON, For. Sec. R.S. Re- 

 ceived December 11, 1873. 



(Abstract.) 



Until lately it was believed that the atmospheric gases dissolved in 

 sea-water could be extracted from it, as from fresh water, by boiling in 

 vacuo. The merit of the discovery that such is not the case is due to 

 Dr. Jacobsen, of Kiel, who found that, in order to drive out the whole 

 of the carbonic acid, the water must be evaporated almost to dryness, 

 and that no amount of boiling in vacuo will suffice to eliminate it. Being 

 particularly interested in the matter, I immediately commenced a series 

 of experiments to determine, if possible, the salt or salts to which sea- 

 water owes this property. 



Preliminary observations satisfied me, in the first place, that sea-water 

 has this property, and, secondly, that solutions of the sulphates of mag- 

 nesia and of lime possess the same property. In order to gain more 

 precise information, two series of experiments were made, the one ana- 

 lytical, the other synthetical. The former consisted in saturating saline 

 solutions with carbonic acid, and then distilling them, the carbonic acid 

 passing in the various fractions being determined ; the latter, in deter- 

 mining the absorption coefficients of two solutions, the one of sulphate of 

 magnesia, the other of sulphate of lime. 



First, the analytical series. Before proceeding to saline solutions, 

 distilled water was saturated with carbonic acid and distilled. The first 

 eighth of the distillate contained abundance, the second a trace, and the 

 remainder no carbonic acid. It may therefore be assumed, in the ex- 

 periments which follow, that the carbonic acid held simply in solution by 

 the water passes almost entirely in the first eighth of the distillate, and 

 that whatever passes afterwards has been retained, in some way or 

 other, by the salt in solution. 



Experiments were made on solutions of sulphate of magnesia, of sul- 

 phate of magnesia and chloride of sodium, and of sulphate of lime, to 

 which were added some on sea-water itself. In every experiment the 

 quantity of solution operated on was 300 cub. centims., which was 

 boiled in a flask connected by a doubly bored cork with a Liebig's con- 

 denser, which was fitted at its other end, air-tight, into a tubulated 



