BAIRD & WLOCK (LONDON) LTD. 



; 



4712 



4713 



4712 s 



Gas Analysis Apparatus, Macfarlane and Caldwell's pattern, modified by Mr. Sodeau, 

 and as used in the Research Department, Royal Arsenal, Woolwich. The apparatus is 

 mounted on polished stand, and has lens sliding on upright for reading graduations on 

 measuring tube ; a 2,1 candle-power electric lamp is also fitted on upright at back of 

 tube. Price, with three special absorption pipettes 



4713 s Stead's Gas Apparatus, mounted on polished mahogany stand, arranged by Mr. J. E. 

 Stead, F.I.C., Middlesbrough. Price with three laboratory tubes and jars, but without 

 battery, coil, and mercury 



4714 s Stead's Gas Apparatus, as above, complete with battery and coil, but without mercury 

 Consists of a measuring tube divided into 270 millimetres and platinum electrodes fused into the upper part 

 of tube. The bottom is drawn out to a bore of about \ in. for attaching an indiarubber tube, and the upper end 

 is contracted and joined at a right angle to the laboratory tubes by a three-way capillary tube, a stopcock being 

 placed at each junction. The whole tube is enclosed in an outer glass cylinder. The auxiliary tube is of the 

 same size, and is also enclosed in an outer cylinder. These tubes are connected at bottom by means of indiarubber 

 tubing with a Y piece, which in turn communicates with the mercury reservoir. 



METHOD OF MANIPULATING THE APPARATUS. 



Having raised the mercury reservoir above the level of the capillary tubes, the cock at the right end of the 

 apparatus is opened, and the mercury forced to the extremity of the tube. An indiarubber tube at the end of the 

 vessel containing the sample of gas is slipped over this open end. By opening the screw clip and the stopcock, and 

 lowering the reservoir, a sample of gas is rapidly transferred into the measuring tube, and when a sufficient quantity 

 namely, about 150 millimetres has passed into it, the clip is screwed down and the stopcock shut off. We now 

 raise the mercury, reservoir until the mercury in the graduated and plain tubes arc at the same level, which point 

 is ascertained by a cathetometer and spirit-level. After carefully noting down the volume of gas enclosed, the 

 mercury reservoir must be raised and the other stopcock opened, and the gas forced into the chamber containing 

 potash. In about two or three minutes the carbonic acid is completely removed, and by lowering the mercury 

 reservoir, and opening again the cock, the gas may be returned into the measuring tube, where its volume is again 



7 



CROSS STREET HATTOTST GARDEK, E- C 



