Mr. J. Y. Buchanan on an Apparatus for Gas- analysis. 3 



When in use the parts A and B are screwed to the back of one 

 wing of the box, A with one and B with two screws {x, oc, x). 

 The back of the box carries four nuts, so that A may be fixed to 

 it close up to the end of the box and with the stopcock y pro- 

 jecting over the side, leaving a space between A and B, the ob- 

 ject of which will be explained further on. 



The different parts of the apparatus will be best explained by 

 describing the manipulations occurring during the analysis of a 

 gas as well as those necessary for introducing the gas into the 

 apparatus. But first we must describe the capillary part of the 

 apparatus between the eudiometer g and the laboratory tube m. 

 The part belonging to A is shown separately in two sections, 

 figs. 2 and 3. The stopcock a has two tubes — the one afford- 

 ing direct communication upwards between the two portions of 

 the capillary tube shown in fig. 3, the other communicating 

 through the prolongation of the stopcock with the air, shown 

 in fig. 2. b, c, and d are ordinary stopcocks pierced to the same 

 bore as the tubes they connect. The capillaries of A and B are 

 connected by a piece of india-rubber vacuum tubing. This tube 

 is 0*003 metre diameter in the bore; and the thickness of its 

 walls is likewise 3 millimetres. The stopcock d communicates 

 with the air through the cup e. When the instrument has 

 been set up as in fig. 1, it is filled with mercury by pouring in 

 at the open legs of A and B, all the stopcocks being open, so 

 that finally the mercury rises a little way up in the cup e. The 

 apparatus being full of mercury, the gas to be analyzed is intro- 

 duced into it either through the opening, <y, of the stopcock a f or, 

 if it is contained in a sealed tube, by interposing it at / between 

 the two parts A and B, A being for that purpose shifted to the 

 further end of the box, and the two ends of the tube in which 

 the gas is collected connected by vacuum-tubing, filled with 

 mercury, with the ends of the capillaries of A and B. The pres- 

 sure in one side of the apparatus is now reduced, either by 

 running mercury from A by means of the stopcock y, or by 

 lowering the movable leg p of B. When the points of the tube 

 are broken the gas rushes into the parts of the apparatus where 

 the pressure is least, its place being supplied by mercury from 

 the other side. The stopcocks are then closed, the tube full of 

 mercury removed, the parts A and B reunited by/, and the ana- 

 lysis proceeded with. When the gas is to be admitted through 

 a, an india-rubber tube is connected at 7 and filled with mercury 

 by opening a, as in fig. 2, and running mercury through it. 

 The point of the collecting-tube, having previously been touched 

 with the file, is pushed into the india-rubber tube ; the other end 

 having also received a stroke of the file, is immersed in a cylin- 

 der full of mercury and the lower point broken off against the 



B2 



