M. R. Bunsen on the Law of Absorption of Gases. 195 



used as distinguishing tests, it is possible that these ordinates 

 may differ so little by the temperatures at which the curves of 

 absorption approach, cut, or are tangent to each other, that a 

 second absorptiometry experiment is necessary. The foregoing 

 experiments, for example, give a value for a, at the temperature 

 19°, of 0-0204: this varies very slightly from the absorption- 

 coefficient of carbonic oxide at 19°, which is found in the table 

 to be 0-0233. The absorption-coefficient of hydrogen at 19° 

 is, however, 0-0193, and that of jethyle gas at the same tempera- 

 ture is 0-0207, and these differ so slightly from the number 

 found for carbonic oxide, that it must remain doubtful which 

 gas is present. In this case the number derived from an ex- 

 periment of absorption in water, is comparable to a reagent 

 which indicates the presence of a group of substances. It only 

 remains therefore to determine by further absorptiometric expe- 

 riments, either at different temperatures or with other liquids, 

 which of the gases indicated by the first experiment is really 

 present. The determination of the absorption-coefficients of 

 gases for alcohol, for solutions of salts and other liquids, forms 

 therefore an important element in gas analysis, as from these 

 any number of conditional equations may be obtained, each of 

 which possesses the importance and value of a new reagent. 



If the material nature of the gas has been determined by the 

 method described by means of u and /3, it is only necessary to 

 substitute the values for » and /3 in the equations (22) and (23), 

 in order to find the quantitative relation in which the two gases 

 are mixed. 



If this calculation is made for the above experiment with the 

 values of a. and /3 as found in the absorption tables for carbonic 

 acid and carbonic oxide, we obtain — 



The same elements which have served to determine the quali- 

 tative nature of the mixture of gases, give therefore the quanti- 

 tative composition with a degree of exactness scarcely surpassed 

 by eudiometric analysis. 



Another problem which may be easily solved by means of the 



absorptiometer, concerns the alterations which a mixture of 



gases undergoes by contact with water. The following example 



imilar mixture of carbonic acid and carbonic oxide shows 



02 



