Wooden Matches for Artillery . 49 
From this comparative trial it follows, that the lime 
tree affords the best wood for matches for artillery ; and 
with it I made the experiments desired by the minister, 
in presence of Mr. Lespagnol. 
There are circumstances in which the service of the 
artillery requires light. Rods impregnated merely with 
nitrate of lead, produce a coal sufficient to discharge a 
cannon, but no light is afforded by them. I conceived, 
that, if they were impregnated with oil of turpentine, 
they might yield flame, without detriment to the action 
of the nitrate : and my hopes were realised, for rods 
thus prepared furnished both light and fire at pleasure. 
In this addition I found two other advantages : one, that 
of rendering the wooden match impervious to water ; the 
other, that of facilitating the reduction of the lead, part 
of which I was apprehensive might be carried off in va- 
pour, and injure the health of those who respired it. 
The theory of the process I adopted is simple ; and it 
is easy to explain, why metallic nitrates succeed better 
than nitrate of potash. However dry the wood may be, 
it always retains a little of its water of vegetation or of 
composition, which is an obstacle to its proper combus- 
tion. By boiling the rods in a solution of nitrate of lead 
or of copper, which on account of its specific gravity re- 
quires a high temperature ; this fluid dilates, softens, and 
penetrates the fibres of the wood, and expels their water 
of vegetation, which is replaced by that of crystalliza- 
tion. The nitrate then conies into immediate contact 
with the carbon of the wood, whence the rapidity of its 
combustion. The nitrate of potash does not answer so 
well, because, retaining much water of crytallization, its 
solution does not acquire so high a temperature : and, 
supposing it able to penetrate the wood as intimately, it 
carries into it too much water, for its combustion to be 
progressive and continual. A proof of this reasoning 
Vol. I. G 
