¥90 Defcription of an Improved Air-Furnace. 
¥ deny the generality of the fa& equally from obfervation. 
I fufpended a piece of flefh, in a proper veffel, over a layer 
of chalk, and at the fame time laid chalk, in fmall pieces, on 
gauze, a few inches above the flefh: but I did not obferve 
that putrefa@ion was more backward than in other eireum- 
ftances, or that putrid exhalations were lefs extenfively dif- 
fufed around. That quickline deftroys putrefaction, is no 
proof of the opinion here advanced, fince this can be ac- 
counted for on other principles. 
If fevers Abound on the oppofite fide of the Tagus, whilft 
the city of Lifbon is free from them, there are probably other 
eaufes to which this may be afcribed, fuch as a marfhy foil, 
&c. Whether any thing of this fort exifts, the account here 
given by Mr. Da Cofta does not enable us to judge. 
It is the tendency of Dr. Mitchill’s theory to overturn fet- 
tled opinions, and to caufe us to abandon’ praétices, which 
have been generally employed, and much rehed on, for the 
deflruGtion of contagious matter. It is of great importance, 
therefore, that it fhould be well founded, left we be induced 
to lay afide means that are efficacious on grounds not fufh- 
ciently eftablifhed. Whatever becomes of Dr. Mitchill’s 
hypothefis, it appears to me to receive no fupport from the 
facts and arguments of the paper in queftion, although it is 
confidered by him as affording a ftrong confirmation of its 
truth. 
Withing every fuccefs to your valuable publication, I re- 
main, oe yours, &c. 
H. CLUTTERBUCK, 
Walbrook, O&. 21, 1799. 
KIL. Defcription of Mr. Howarn’s Improved Air- Furnace, 
i HE difficulty of obtaining a degree of heat fufficiently 
intenle for many operations in chemiftry, has been felt and 
lamented by every one engaged in fach purfuits; and, not- 
withftanding the refearches and -numberlefs experiments 
made profefiedly for that purpofe by the greateft men, the 
beft conftruction of an air-furnace is {ti]] a problem; in- 
deed, 
es 
