544 Scientific Proceedings, Royal Dublin Society. 



even considerable pressure without any danger of being broken, 

 and, as will be explained afterwards, when the laboratory vessel is 

 fixed in position for working, a decided pressure is exerted against 

 the tube g. 



The contracted portion of the burette immediately below the 

 stopcock is about 225 mms. long, and has a capacity of 15 c.c. ; the 

 wider portion is about 410 mms. long, with a capacity of about 

 250 c.c. Both portions are graduated, the former at intervals of 

 1 c.c, and the latter at intervals of 25 c.c. 



The pressure tube is 1000 mms. long; and since it can be em- 

 ployed both as an open and closed tube, a volume of a gas may be 

 measured under a pressure equal to 1500 mms. of mercury, or, on 

 the other hand, under as low a pressure as 1 mm. Thus the appa- 

 ratus is more sensitive than Thomas' (Chem. Soc. Joum., 35, 217). 



The laboratory vessel differs in principle and shape from the one 

 employed in Frankland's or Macleod's apparatus. The cylindrical 

 portion n is 25 mms. internal diameter, and 55 mms. long, and is 

 furnished with the side tube o for connecting the vessel with an 

 independent mercury reservoir : the portion p is 45 mms. in diameter 

 and 100 or 190 mms. long, according to the character of the analysis 

 to be made; this portion of the vessel, which is shown in the drawing, 

 has a length of 100 mms., the most useful size for water analysis. 

 The upper part q, which has an inverted conical shape, is 55 mms. 

 long, the diameter decreasing from 20 mms. at the mouth to 4 

 mms. at its narrowest part. Two platinum wires are sealed into 

 the vessel in the positions shown in the drawing. 



The particular shape given to the portion q allows the labora- 

 tory vessel to be easily connected or disconnected with the tube g. 

 When the laboratory vessel is placed in position, as represented in 

 the drawing, the tube g, the end of which is fitted in an indiarubber 

 collar, tightly closes the narrow part of q, while the lower shoulder of 

 the vessel rests upon the shelf f, which, in plan, has somewhat the 

 shape of an inverted U . If the space above the collar be filled with 

 water or mercury, a perfectly air-tight joint is obtained. The joint, 

 in fact, may be made so staunch that, when the vessel is arranged in 

 the manner described below, a torricellian vacuum may be maintained 

 in it. When it is desired to disconnect the laboratory vessel, its lower 

 portion is drawn forward sufficiently to clear the shelf, and is then 

 lowered to detach it from the tube g. By reversing these movements 



