1897.] Newly Prepared Gases. 355 



tubes T-y and T 2 . The tube T X) through which the cylinder was 

 filled, had several layers of fine copper gauze across the broad 

 end, which tended to distribute the gas evenly across the section. 

 The whole apparatus was contained inside a screen S, the ends A 

 and B of the tubes leading to the cylinder projecting outside the 

 screen ; by this means the charged gas could be blown out of the 

 cylinder, without stirring any apparatus or tubes inside S ; so that 

 the deflection on the electrometer scale, when C is connected to 

 the insulated quadrants, was solely due to the removal of the 

 charge inside 0. Any effect of gravity, on the motion of the 

 carriers towards the sides of the tube, was prevented by placing it 

 in a vertical position. 



(11) The gases that were examined were the oxygen and 

 hydrogen given off by electrolysis of dilute sulphuric acid. The 

 cell was raised to a temperature about 20° above the room, at 

 which it could easily be kept by running the current. By means 

 of an ammeter and variable resistance in the circuit the current 

 could be kept constant. A method is thus provided of filling the 

 cylinder several times with a gas having a constant electrification 

 per c.c. When filling the cylinder with the hydrogen it is best 

 to lead the gas in at the top, and when using oxygen at the 

 bottom, in order that the air may be driven out in as short a time 

 as possible, as it is not desirable to run the current for more than 

 five minutes at a time, when a number of experiments have to be 

 performed requiring the same electrification in each case. 



The gases were first bubbled through potassium iodide ; and 

 then through strong sulphuric acid, so that they should enter the 

 tube D perfectly dry. The cylinder and tubing connected with it 

 were thoroughly dried by heating them with a Bunsen burner and 

 then blowing dry air through. This precaution is absolutely 

 necessary as it only requires a very slight amount of moisture to 

 form a cloud, and this would impede the motion of the carriers. 



(12) A series of experiments of the following type were then 

 performed : The cylinder was connected to a pair of quadrants of 

 the electrometer, which were kept to earth while the cylinder was 

 being filled and insulated before blowing out the gas, so as to get 

 the readings on the same part of the scale. The tube A was 

 closed, and D connected to the delivery tube of the sulphuric acid 

 wash-bottle, and a current of 14 amperes sent through the cell. 

 It only required the current to run for about five minutes to com- 

 pletely fill G with the charged gas. The circuit was then broken 

 and the tube B closed. At the same time a stop-watch was 

 started. After the lapse of t minutes the ends A and B are 

 opened, and dry unelectrified air blown through G to expel the 



VOL. IX. PT. VII. 29 



