68 Procefs for deftroying Contagion. . 
if permitted to vibrate, its temper or elafticity fuffers not 
the fmalleft diminution. 
A gentleman, fome few years ago, eftablifhed 2 mill for a 
manufaéturing purpofe, in which, having occafion to apply 
fprings under the circumftances mentioned above, he at firft 
attempted to make ufe of metal ones, but in yain, being 
never able to make them ftand a fingle day’s work. He 
tried every kind of fteel, and employed many different work~ 
men, but {till without fuecefs. Merely as a temporary ex- 
pedient, till fuch time ag he could get a freth fupply of fteel 
fprings, he one day tried a wooden one, which, to his 
agreeable furprife, completely anfwered his purpofe; and 
from that time, as may be concluded, he never ufed any 
other than wooden ones. The experiment was perfeétly 
decifive : the fprimgs were in daily action for four years fuc- 
ceffively, making, in a common way, from forty to fifty 
ftrokes in a minute on an average. ‘At the expiration of the 
four years, thofe fprings which had efeaped accidents were 
as elaftic, and as ftrong, as when firft put into a€tion. The 
wood they were made of was red deal, clean grained, and 
perfectly free from knots. 
To many manufacturers who employ machinery for va- 
rious purpofes, in which fprings, that muft be fuffered to vi-. 
brate, form a part, this information, which may to fome ap- 
pear trivial, will be found highly ufeful. 
XI. The Procefs fuggefled by James CARMICHAEL 
SmrrH, M.D. F.R.S. Fellow of the Royal College of 
Phyficians, and Phyficicn Extraordinary to bis Majefty, 
for determining the Effect of the Nitric Acid in deftroying 
Contagion. Extra&ted from An Account of the Experi- 
ment made at the Defire of the Lords Commiffioners of 
the Admiralty on board the Union Hofpital Ship. 1796- 
Tu E. fubje& of this article is of the greateft importance, 
and the fa&ts which have been eftablifhed by the experi- 
ments 
