ON THE SO-CALLED u INACTIVE” CONDITION OF SOLIDS. 
125 
Nvise. It loses this property if kept for some time in the solution, or if previously im¬ 
mersed in water or heated, and hence it has been concluded that it is not the solids 
that disengage the gases, hut the air in contact with them. It is assumed that a solid, 
whatever its polish, “ is covered with roughnesses that form a set of network of capillary 
conduits, into which the surrounding gases penetrate and condense,” and “the gas- 
bubbles thus imprisoned become the centres to which pass those which are dissolved.” 
It is supposed that a lengthened immersion in water, or exposure to heat, renders the 
solids “ inactive ” by removing the air from their surface. 
It is with diffidence that I venture to cast a doubt upon a theory, supported as this is 
by ingenious reasoning and experiments, and the applause of the scientific world; but, 
as the only object with which we cultivate science is, or ought to be, the discovery of 
truth, so the earnest student will not the less welcome her, even though she be not 
smiling on his pet theory. One of the best and wisest of French philosophers says, “ II 
ne faut pas juger de la nature selon nous, mais selon elle.” 
When a bottle of soda-water is uncorked and poured into an ordinary drinking-glass,* 
after the brisk effervescence is over, the sides and bottom of the glass are more or less 
covered with bubbles of carbonic acid. If the glass were chemically clean, these 
bubbles would form in much less quantity, or not at all. 
Exp. 1.—Two test-glasses, A and B, were selected, and wiped out with a clean cloth. 
A was then filled with methylated spirits of wine, and rinsed out with water to get rid 
of the adhering spirit. A bottle of soda-water was then uncorked, and gently poured 
into the two glasses. B was profusely covered with gas-buhbles. Not a single gas- 
bubble was seen on the surface of A. 
Exp. 2.—A glass rod and a platinum spatula that had been long exposed to the air 
were dipped first into A, then into B. Gas-bubbles were abundantly liberated from the 
surface of both. They were dipped into spirits of wine, rinsed in water, then placed in 
A and B. Not a bubble of gas appeared on either surface except above the points 
at which the bodies had been made chemically clean, and there plenty of gas-bubbles 
appeared. Indeed, it was accurately determined by the formation of those bubbles 
how far the rods had been dipped into the spirit. 
Now in these cases, where the surface is made chemically clean, the attraction of 
adhesion between the liquid and the surface is perfect. The clean surface is completely 
wetted, and there is no liberation of gas.f But let the surface be not chemically clean 
(and it readily becomes so by even a few minutes’ exposure to the air, or by handling, 
etc.) then the adhesion is imperfect; the liquid does not wet the surface completely, 
and the gas, yielding to the superior attraction of the solid, adheres to it. That is, where 
there is but small adhesion between the liquid and the solid there may be strong 
adhesion between the gas and the solid; and hence it is that bodies not chemically 
clean are favourable for the liberation of gases from their solutions-.J 
But it is said that the condition of the surface as to roughness or smoothness has 
much to do with the action of the solid in liberating gas. I do not find such to be the 
case, provided the condition of chemical purity be attended to. 
Exp. 3.—A rat’s-tail file, that liberated gas abundantly on being immersed in soda- 
water, was washed in spirit and rinsed in water, but it still liberated gas. It was then 
held in dilute sulphuric acid for about a minute, until there was a decided smell of 
hydrogen ; it still disengaged gas. It was then put into spirit, and kept there during 
some hours. When immersed in fresh soda-water, not a single bubble of gas appeared 
on the surface of the file. 
Exp. 4.—The file was dried with a duster and drawn through the moist hand, when, 
on being placed in soda-water, it liberated bubbles of gas abuudantly. It was now no 
longer chemically clean. 
* In opening a bottle of soda-water, there is generally a waste of liquid at the moment the 
cork flies out, in consequence of the retroactive motion of the bottle. This may be prevented 
(unless the liquid be very highly charged with gas) by resting the bottle firmly and upright 
on a solid support while removing the cork. 
f I find spirits of wine more efficacious in cleaning the surfaces than sulphuric or nitric 
acid, ammonia, or caustic potash solution. 
£ A bottle of nitric acid that had become of a dark orange-colour by exposure to the light 
disengaged gas freely from the sui'face of a platinum spatula put into it. When the spatula 
was made chemically clean, there was scarcely any discharge of gas. 
