[ I 37 ] 
XVI. ASlual Fire and Detonation produced 
by the Contact of Tin-foil, with the Salt 
comp of ed of Copper and the Nitrous 
Acid. By B. Higgins, M. D. Communi- 
cated by R. Brocklefoy, M. D. F. R . S. 
■and of the Royal College of Phyficians 
in London, 
Read Dec. 24 , *77 vO EVER AL pieces of thin flieet- 
and Jan. 28 , ! 773*^^ copper, placed vertically, and 
at a fmall diftance from each other, in the ftrong 
nitrous acid diluted with half its quantity, or 
more, of water, and futfered to remain in a clofe 
veflel, until the acid is faturated, afford a cryftalline 
blueifh green fait, which is to be feparated from the 
undifiolved copper and the fuperfluent green liquor, 
and kept in a well-corked bottle ; becaufe, on ex- 
pofure to the air, it deliquefces, 
This fait, taken moi'ft, but not very wet, and 
beaten to the finenefs of bafket fea-falt, in a mor- 
tar, is to be {brewed to the thicknefs of a {hilling, 
on a piece of tin-foil, twelve inches in length 
and three in breadth. 
Then the foil is to be inftantly rolled up, fo as 
to include the fait, as it lay, between the coils. 
The ends are to be {hut by pinching them toge- 
Vol. LXIIL T ther, 
