10 
DR. W. A. BONE AND MR. R. Y. WHEELER ON THE COMBINATION OF 
experiment over a wide range of pressure (from about 500 millims. to as low as 
20 millims.), so that practically the whole velocity curve may be determined, and 
(2) that in cases where the gases are not originally present in their combining ratio, 
it is possible to follow the variations of the velocity with an ever increasing excess of 
one of them. 
The glass globe A (capacity = about 1200 cub. centims.) serves merely as a 
reservoir for the reacting gases; it contains a few cubic centimetres of distilled water, 
so that the gases are kept saturated with aqueous vapour at the room temperature 
(which is indicated by a thermometer placed with its bulb in contact with the outer 
wall of the globe). 
From the globe the gases are drawn by the automatic Sprengel pump F (the 
“ circulating pump ”), at a uniform rate, through the Jena hard glass combustion 
tube BC, containing the surface under examination, and which is heated in the 
Lothar Meyer constant temperature furnace D. This furnace is protected from 
draughts by a thick asbestos hood (indicated by dotted lines in the diagram), at each 
end of which are arranged suitable screens in order to shield the rest of the apparatus 
from radiated heat. The gas supply of the furnace is regulated by a Stott’s 
governor, which keeps the temperature constant for, if necessary, many days 
together. 
Each end of the combustion tube is fitted with special glass joints (act) composed 
of rings of glass of gradually diminishing hardness fused together, ending ultimately 
in a grade of glass soft enough to allow of its being fused direct on to the mercury 
cup taps Jjl). The adoption of these special joints obviated the use of any indiarubber 
connections in the apparatus. The mercury cup taps, bb, are in turn connected, by 
fused glass joints, with the ground glass joints cc, each of which works under a 
mercury seal. An enlarged drawing of one of these joints is shown in the diagram 
(fig. 2). This device allows of the ready removal of the entire combustion tube, and 
its transference to similar mercury sealed joints, cV, in the “ absorption apparatus” 
(fig. 4), to be described later. 
On leaving the combustion tube the gases pass through a glass worm, E, 
surrounded by a water jacket (not shown in the diagram), through which a stream of 
cold water is constantly maintained, to ensure the rapid cooling of the hot gases and 
the condensation of steam. The cooled gases then pass onwards to the automatic 
Sprengel pump F, which delivers them up into the vertical tube, G, standing over 
mercury in the trough H; thence they pass along the horizontal tube, KK, back 
again into the globe A, thus completing the circuit. . 
The apparatus is closed by the mercury cup tap, cl, sealed into the j_-piece L. The 
other side of d is connected, by a fused glass joint, with the three-way tap e, through 
which communication may be made either with the gas-holder containing the experi¬ 
mental mixture, or with an auxiliary automatic Sprengel pump used for the rapid 
exhaustion of the apparatus as circumstances require. The pressure in the apparatus 
