438 
SIR B. C. BRODIE ON THE ACTION OE ELECTRICITY ON OASES. 
reagents, and to estimate the variations in volume which the gas undergoes under the 
influence of these reagents with facility and precision. 
The oxygen employed in the following experiments was procured either by the 
decomposition of pure chlorate of potash or by the electrolysis of dilute sulphuric acid. 
In the former case the oxygen was collected in one of the sulphuric-acid gas-holders, 
hereafter described, and thence passed through the induction-tube. In the latter case it 
was passed through the induction-tube immediately from the apparatus in which it was 
generated. I shall describe the latter arrangement, which was employed in all but my 
earliest experiments, and which presents many advantages. 
A drawing of the vessel in which the oxygen was generated is given in Plate LI. fig. 1 : 
a is a glass vessel, similar to a small gas-jar, open at bottom ; this vessel is cemented into 
a cell of porous earthenware, b, by which its aperture is closed ; c is a ring of coke, being 
a section of one of the cylinders employed in Bunsen’s carbon-battery ; to this is attached 
a platinum wire d. In the interior of this glass vessel is a platinum plate, to which is 
attached a second wire ( e ) of the same metal passing through a stopper of caoutchouc. 
The whole is immersed in a glass jar containing dilute sulphuric acid, with which the 
vessel a is also partially filled. The wire d is connected with the zinc, and the wire e 
with the platinum terminal of a voltaic arrangement, consisting of three or four Grove’s 
cells ; the hydrogen passes into the external air, and the oxygen is delivered through the 
tubejf, in which two bulbs (g) are inserted containing a solution of iodide of potassium, 
for the purpose of destroying the traces of ozone which would otherwise be contained in 
the gas and interfere with the experiment. 
The oxygen delivered at f is then passed in a slow stream through a tube of the form 
delineated in figure 2, containing pure and concentrated sulphuric acid, the tube being 
attached at g by a caoutchouc junction to the tube./; the gas, thus deprived of moisture 
by the sulphuric acid, is further and completely dried before entering the induction-tube 
by anhydrous phosphoric acid contained in three small bulbs attached to the tube. 
In figure 3 is given a drawing of the induction-tube, which is fundamentally of the 
kind originally devised by Siemens, and described by him in Poggendorff’s ‘Annalen’ in 
the place before referred to. The tube, however, is not, as in the arrangement of 
Siemens, coated with tinfoil, but the inner tube is filled with water, in which is placed 
one of the terminal wires of Ruhmkorff’s coil, while the tube itself is immersed in a 
vessel of water connected with the other terminal wire of the coil. The gas enters 
the apparatus at h, and passing over anhydrous phosphoric acid contained in the three 
bulbs i, traverses the narrow space k between the two tubes, and is there submitted 
to the electric action, after which the electrized gas is again passed over anhydrous 
phosphoric acid contained in the three bulbs l , and is delivered at m. 
The gas is thus submitted to the electric action in a very dry condition, which is an 
essential point for the production of a considerable percentage of ozone. The amount 
of ozone is also affected by the temperature at which the gas is thus operated on. It is 
especially desirable to prevent the elevation of temperature consequent on the electric 
