430 IMPORT'S ON THE STATE OF SCIENCE. 



The two long tubes were respectively used to admit gas and to syphon 

 off samples of saturated solution. 



In the case of the more soluble gases 20a the specific gravity of the 

 solution was determined and the expansion due to the absorbed gas 

 allowed for. The gases were estimated by chemical methods. 



Fernet 18 measured the volume of the gas to be dissolved over 

 mercury in a eudiometer tube which was surrounded by water; the 

 absorption was carried out in a separate vessel, also kept in a water- 

 bath, and which could be connected with the eudiometer. 

 -sore When determining the solubility of ammonia Carius 23 passed 



' the gas through water contained in a tube constricted and blown 

 into a small bulb. At saturation, tbe bulb was closed by a rod ground 

 to fit the constriction. The liquid above the constriction was then run 

 out and the bulb dried and weighed. The volume of the bulb being 

 known, the weight and specific gravity of the solution were simul- 

 taneously determined. 



Roscoe 2S saturated water with a mixture of hydrogen and chlorine and 

 compared the amount of chlorine dissolved with that which would have 

 been dissolved if the gas absorbed was proportional to its partial pressure. 

 1 ft . q Roscoe and Dittmar 29 used an absorption bulb having the inlet 



tube twice bent and joined to the bottom of the bulb, the outlet 

 tube being joined to the top of the bulb ; both tubes were constricted to 

 facilitate sealing off. The bulb was half filled with water and immersed 

 in a water-bath, and gas passed through, either under ordinary or under 

 increased pressure. When saturation was reached the stream of gas 

 was continued for thirty minutes, then the apparatus was closed by a 

 rubber tubing and pinch-cocks, immersed in a freezing mixture, and 

 sealed at the constrictions. After weighing, the contents of the bulb 

 were analysed. 



For determinations under reduced pressure a small flask with con- 

 stricted neck was partially filled with a solution saturated at a lower 

 temperature, and joined to a manometer tube dipping under mercury. 

 By heating the bulb gas was expelled and displaced the air in the 

 manometer. When sufficient gas had been driven off the flask was 

 cooled and placed in water at the required temperature; the mercury 

 rising in the manometer. When equilibrium was attained the pressure 

 was observed and the flask sealed at the constriction. 



These authors tried Carius' method (vide this Section 1856), but 

 found that it gave low results owing to the solution being open to the air, 

 so that the partial pressure of the gas was less than the atmospheric 

 pressure. 



■•ofu Robinet 33 determined the amount of gas in a liquid by boiling 



the liquid in a eudiometer tube over mercury and measuring the 

 volume of the gas expelled. 



1ftfi7 Khanikof and Louguininc 42 used Bunsen's method, so modi- 



' fied that the absorption tube could be rotated in a bath of water. 

 1 When determining the solubility of ammonia in water 



' Raoult 53 passed the gas through a known quantity of water con- 

 tained in a flask; the out-flowing gas was passed through a (J -tube, 

 containing solid potash to retain water, and the absorption flask was 

 placed in a well-stirred water-bath maintained at a constant temperature. 



