100 Dr Turner's Experiments on the Appiication of 
Of course, it would be hazardous in the extreme to try this ex- 
periment on a considerable quantity of gas. The explosion does 
not occur immediately on the introduction of the metal into the 
mixed gases;, the combination takes place at first silently and 
gradually, though rapidly ; the metal is in consequence heated, 
then becomes dull red, at last passes to bright redness, and at 
the same moment the remainder of the gases unites with an ex- 
plosion. This succession is commonly so rapid as to escape ob- 
servation, but I shall afterwards relate an experiment which 
shows the order distinctly. It hence appears that the platinum 
differs somewhat in its mode of action from electricity ; the lat- 
ter agent causes the whole mass of gases to unite at once, and 
an explosion is the necessary consequence ; whereas the plati- 
num causes them to explode, not by its primary action, but 
through means of the heat disengaged by that action. Thus, 
although platinum, in its state of greatest activity, will general- 
ly cause an explosion, when brought in contact with |th cubic 
inch of a very pure explosive mixture ; yet, if the quantity be 
still less, there is no explosion, since, before heat enough is de- 
veloped for this effect, the whole gas is consumed. 
When spongy platinum is put into a mixture of hydrogen 
and atmospheric air, a copious dew condenses on the surface of 
the mercury, and this effect was observable, even when the hy- 
drogen bore a small proportion to the whole quantity of gas 
operated on. Several very interesting points of inquiry were 
suggested by this fact ; but, before proceeding to their investi- 
gation, I found it necessary to avoid certain inconveniencies at- 
tached to the employment of spongy platinum, as prepared by 
the ordinary process. Its delicacy, for instance, is such, that it 
often falls to pieces from the pressure necessary to pass it under 
the mercury ; or, at all events, its porous texture is so much in- 
jured from this cause, as to render its action irregular. Ano- 
ther serious objection to its employment in this state, is the fa- 
cility with which the mercury acts upon it, particularly when 
heated. I observed this fact in a very marked mannerj on the 
following occasion. I had warmed the platinum gently with the 
view of increasing its energy ; but it was no sooner plunged un- 
der the mercury than an amalgam formed, which sunk instant- 
ly to the bottom of the trough. On driving off the mercury by 
