L r 4° J 
with it, and affiHs in the detonation, which is 
common to all nitrous compofitions in fimilar 
circumftances. 
If the fait be very wet, there will not be much 
fire or explofion, becanfe the heat will be diffipated 
before the fait can be fufficiently dried in every 
part. 
If the fait be not moift, it cannot commence 
the action which is neceflary ; and there will be 
no fire,, becaufe there can be no haHy folution of 
the tin to give the requifite heat. 
If the tin and fait be not coiled up in due time, 
there will be very little heat and no fire ; becaufe 
the diffipation of the heat from a broad expanfe,. 
keeps pace with the generation of it; and as the 
moifture exhales quickly in this manner, there is 
none left to renew the adtion on the tin and confe- 
quent heat, when the proper time of coiling has- 
elapfed. 
A piece of tin-foil, larger than that I have de- 
ficribed, cannot eafily be managed ; finaller pieces- 
give lefs fire in the diredt proportion of their fur- 
faces, and the quantity of fait which they can, at 
the fame inftant, reduce to the required Hate of 
drynefs. 
The fudden diffipation of the moifture appears 
to me the moft curious of thefe phenomena. To 
render it the more obfervable, I made the following 
experiments. 
I placed a piece of tin-foil, twelve inches long 
by two broad, loofely coiled,., and Handing verti- 
cally on the flatteH end, in half a table-fpoonfui 
of the faturated folution of copper in the diluted 
nitrous acid, and found that l'carce fiv£ feconds 
elapfed 
