404 STUDIES ON THE PHENOMENA OP CONTACT. 



Pj 3 The polarity -wliich was developed between the hy- 



jjl- , drogen and oxygen by the action of heat is now 



^^ developed between these by the presence of the 



TJ-ij|';jl| -..^ , platina. The negative electricity of the hydrogen 



i >r~K tends to combine with the positive fluid of the platina, 



i Qt'l^jPt while the positive electricity of the oxygen tends to 



'; ^^ unite with the negative fluid of the metal. The 



€|FNi .....--'''' oxygen and hydrogen become thus negative and 



^ positive in relation to one another, and can, conse- 



^^' quently, unite. Thus the two gases combine in 



neutralizing their proper electricities. When, in place of using a simple wire 

 of platina, we augment the surface of the latter by employing what is called the 

 sjjonge of platina. tiio action is much more intense. In this case the platina 

 becomes incandescent in consequence of the electric action exerted on the sur- 

 face of that metal, and the heat developed is such that the hydrogen is eventu- 

 ally kindled. 



I shall doubtless be asked if it is possible to prove, by FJff- ■*. 



direct experiment, that these phenomena really take place, ^'^7 

 and if we have not here, also, an hypothesis or gratuitous /f":..-\- '' 

 supposition. I shall proceed at once to support by cxperi- -; ''^ 

 ment what I have just advanced, having only wished, in |||j' 

 order to make myself more clear, to indicate the theory ^';^'- 

 first and enter upon the facts afterwards : '^ ' 



Take two tubes of glass, one containing oxygen, the other hydi'Ogen gas, 

 and place them upon water which is acidified with a drop of sulphuric acid to 

 make it a better conductor. Let there be then introduced into each tube a 

 strip of platina, so that it shall be plunged in the gas of the respectire tubes 

 and be then bent back under the water in oider to project from the surface of 

 the liquid. So long as the two strips of platina thus disposed remain separated, 

 we shall realize notliing ; but let them bj united by a galvanic multiplier, and 

 there Avill instantly be perceived on the magnetic needle the action of the current 

 proceeding from the strips of platina. We have thus, therefore, created a voltaic 

 arrangement, by means of which Ave may produce all the effects which would bo 

 yielded by an ordinary pile. Fifty of these elements united constitute tho 

 celebrated gas battery of M. (irovc, Avhich is well known to all oui 

 readers. When the slips of platina present to the gas in the tubes a small 

 surface, the action is feeble, and it increases wilh the extent of the surface 

 of metal in contact with the gas. When this species of pile is exclusively cm- 

 ployed in decomposing Avater, the volumes of the gases proceeding from 

 the decomposition and collected in the voltameter are, both for the hydrogen 

 and the oxygen, exactly equal to the sum of the volumes of these gases which 

 disappear in the tubes of the pile. In proportion as the work goes on, the 

 volumes of the gases in the tubes diminish ; tin^y are visibly absorbed, and the 

 volume of hydrogen which disappears is always double that of the oxygen. 

 We see the same process here as Avhen we burn hydrogen by means of 

 oxygen, at the ordinary temperature, by the contact of the spongy platina. 

 Here, therefore, is one experiment in support of our assertions. Let us pass 

 to others : 



If we place a small gauge, made of a tube from tAvo to three millimetres in 

 diameter and filled with hydrogen gas, on a vessel containing a concentrated 

 solution of chloride of gold, at the end of some days, if the temi^crature has not 

 sensihlij varied, the level of the chloride in the interior of the tube is little dif- 

 ferent from Avhat it was previously; but if a platina wire be introduced from 

 beloAV into the gauge in such manner that it shall be in part immersed in the 

 hydrogen gas and in part immersed at its loAver extremity in the solution of gold, 

 we see the gas diminish in volume in the interior, and even completely disap- 



