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

 If we substitute a, b, c for the coefficients ^5- in the first 



for 



equation, «, b l c, for == , p in the second, and « 2 



,t? r-m- in the third, we obtain 



x _ A _b 1 c 2 — 6 2 c, +b 2 c—bc z + bc l — b l c 

 y B ac i — ac- l -\-a x c — a l c !i + a <i c l — (L 2 c' 

 z C ab^ — ab^ + a^—a^b + a^b — a^by 

 y~"B — ffo 2 — flCj + a^ — fljCg + flgC, — a 2 c ' 

 or 



V ~ ? (16) 



aj + y + ^-A + B + C 



A 



a?+y + * A + B + C 

 * C 



. . . (17) 



z+y+e "A+B + C (18) 



The foregoing formulae are founded upon the well-known 

 hypothesis of Dalton and Henry, which, however, is not con- 

 firmed by the extremely inaccurate experiments hitherto made 

 upon the subject. In order to verify them, it is necessary in 

 the first place to obtain an exact determination of the coefficients 

 of absorption ; for this purpose I use an absorptiometer of the 

 following construction : — 



The absorption-tube, e e, Plate I. fig. 1, divided into milli- 

 metres and calibrated, has a small iron band b, furnished with a 

 screw luted on to its lower and open end ; this fits into another 

 screw attached to the small iron stand a a, fig. 2. By this arrange- 

 ment the open end of the tube can be screwed down against a 

 plate of caoutchouc covering the lower suiiiice of the stand, and 

 the tube thus hermetically closed. On each side of the stand 

 are fixed two steel springs c c, which fit into two upright grooves 

 inside the wooden foot of the apparatus/, fig. 1, so that the 

 stand can be either raised or depressed, but not turned on its 

 axis. It is thus easy, when the tube and stand are in their 

 places, to open or close the absorption-tube by giving it a very 

 slight motion on its axis to the right or left. The outer cylinder 

 g g, fig. 1, surrounding the absorption-tube is not luted either 

 into the wooden foot/, or into the iron rim h, but the screws ii 

 press the ground-glass edges of the cylinder against the caout- 

 chouc rings. The tubes r r serve to pour in mercury, so that 

 any wished-for pressure is obtained in the absorption-tube by 

 raising or depressing the column of mercury in the inner glass 

 cylinder. The temperature of the surrounding water is deter- 



