90 DENSITIES OF f)XY(JEN AND HYDROGEN 



stopper of the large eudiometer, after wliicli the .spark was passed. The two stop- 

 pei-s were then again opened, and the process repeated fi-oni four to twenty times. 

 At tl)e end of the process the [)ressure in the globes was observed, thus determining 

 the vi)lume withdrawn for analysis. The globes were kept surrounded with ice 

 during the whole course of the e.xperiments. 



It is obvious that the measurement and analysis of the residue coulil not lie 

 effected in the large eudiometei. This was therefore connected by a leakagepioof 

 mercurial valve, with a self-acting Toepler pump. When the htst e.vplosiuu had 

 been made, this valve was opened, and the pump set in action. The large quantity 

 of water formed during the explosion had to be absoi'bed between the eudiometer 

 and the pump. A special form of drying tube was constructed, but it is hardly 

 worth while to describe it. It may suffice to say that the diying agent was pure 

 sulphuric acid boiled iu a vacuum till it did not give off a harmful tpiantity of ab- 

 soi'bed gas, and that this acid could be flowed over the glass beads filling the dry- 

 ing chamber. Even after absorbing fifty grammes of water, it wa.s so effective 

 tliat a vacuum of two or three millionths could be attained. 



From the Toepler pump, the gas was transferred to a Bunsen eudiometer. 

 Owing to the fact that the explosion in the large eudiometer did not extend to the 

 surface of the meicury, there was always enough uncombined oxygen and hydro- 

 gen in the residue to admit of satisfactory explosion, after wliifh the residue was 

 analyzed. 



14. DKNSITY Ol' MIXKD GASES. CAN ELECTUOLYTK" (J AS UK (UnAINKl) IN AIOMIC 



PUOrOKTIONS ? 



In all my expeiinients, I found an excess of hj^drogen. This is due to second- 

 ary reactions in the electrolytic cell, attended with consumption of oxygen. Now 

 it is one of the innumerable possible cases that there should be an equilibrium 

 between the production and destruction of the oxide formed, so that for a time 

 the two gases should be delivered in atomic pioportions. But all the precaiitious 

 which occurred to me were used in vain. Tiie voltameter was treated in a manner 

 perfectly uniform, and used only at the temjjerature of melting ice, but there was 

 always an excess of hydrogen. 



Once, to learn a little about the stal)ility of any suppo.sed equilibrium, I con- 

 nected the voltameter directly to the deliveiy tube leading to a Bunsen eudionietei- 

 containing a measured quantity of hydrogen, designed to prevent oxidation of mer- 

 cury. The eudiometer stood deeply in mercury covered with siilpliuric aciil. 

 Electrolytic gas wa.s introduced and exploded for many times; the aniouiit of 

 hvdroi^en graduallv increased. The current was now iiicie!V.sed so as to warm tiie 



