on the Diffusion of Gases, 8rc. 



75 



cylindrical glass receiver A, 9 inches in length, and /O^ 

 0.9-inch internal diameter, divided into 150 equal 

 parts, and provided with a stopper B, fitted into 

 the mouth of the receiver by accurate grinding. 

 The stopper was perforated longitudinally, cavity 

 cylindrical, 0.34-inch in diameter, and 1.8 in length. 

 Into the cavity of the stopper there was again 

 ground a short piece of stout tube, having a bore 

 of 0.07 or nearly y^.-y inch, and bent into a right 

 angle in the middle ; such as C. These were the 

 dimensions of tube A ; but after several experi- 

 ments that tube was laid aside, and a second and a ... 

 wider tube, of 0.12-inch bore and 2 inches in I L^ c 

 length, was ground into the aperture of the large stopper B, 

 and bent in the middle, like tube C. 



B 



I. — On the Diffusion of the different Gases into atmos- 

 pheric Air. 



The receiver, above described, was filled in succession with 

 various gases in a state of purity, and supported in a horizontal 

 position upon a frame, within a box, with the end of the 

 bent tube pointing upwards, Fi 9- I- 



when the contained gas was r~ 

 heavier than air (fig. 1), and ^- 

 downwards, when the gas 

 was lighter (fig. 2), to avoid 

 any tendency of the gas to 

 flow out of the receiver. 

 After the gas had been 

 allowed to diffuse into the 

 air through the tube for a 

 certain time, the receiver was transferred to the pneumatic 

 trough, and the quantity of air which had entered, and gas that 

 remained, ascertained. Two or three and sometimes more 

 experiments were made on each gas, and the results found to 

 be regular, or to vary within moderate limits. 



(1). After diffusion for ten hours, through tube I, there 



