162 
CHELEL, relative to thedampnefs acquired 
by gunpowder. The following is the 
fubftance of Dr. Mirchell’s Opinion, as 
given in the Medical Repofitory, publithed 
at New York :—‘ The evil complained 
of muft be fought for in the faltpetre, 
which coniifts of three diftin@ materials ; 
1. Potath: 2. The acid of putrefa&tion ; 
and, 3. Water. Thele are combined in 
certain proportions, and made to cohere 
by an attractive force. When the coniti- 
tuent parts are pure, and well-pioportion- 
ed, they form fine and unadulterated falt- 
petre ; but it very often happens that fome 
of the component parts of falepetre are 
not pure, or, if pure, not compounded in 
due proportions: 
¥. The potath, or alkaline bafis of faltpetre, 
is frequently imperfe@ in its conftitution, or 
Vitiated by foreign admixture. Common or 
fea fait ts fometimes combined with it. This, 
however, is not all. A mixture of lime is 
often derived from the plafter and other cal- 
careous matter, which abounds in the falt- 
petre beds and collections. This earth has 
been found, by experience, to weaken the 
ftrength of the powder in two ways. 1..By 
adding to the weight of that manufa@ured 
article unacidified lime, which is an inactive 
Ingredient. and which has no exp'ofive foree; 
or, 2. By difpofing powder to grow damp,‘ 
whenever acidified lime exifs in the form of 
a feptite, and exercifes its inherent attractive 
pewer of imbibing moifture from the atmo- 
fphere and other furrounding obje@s. In the 
former cafe, powder, though dry, will be 
weak ; in the latter it will imbibe humi- 
dity, and alfo be weak of courfe. Some 
years ago, under the French Monarchy, the 
want of a due explofive force in the powder 
with which their artillery was ferved, became 
a fubje&t of public inquiry. The Academy 
of Arts and Sciences traced it to an acciden- 
tal adulteration with lime and calcareous mat- 
ter, in the Parifiazn manufaMories. To ob- 
viate this difficulty they recommended an ad- 
dition of as much good Ruffian or other potath 
to the falipetre-beds as would faturate com- 
pletely al! the feptic acid, and of courfe dif 
charge or precipitate all the lime. . By atten- 
tion to tais, the quality of the faltpetre was 
improved. This may be done when faltpetre 
abounds either with combined or uncombined 
linie. Diflolve it in water ; and pure potahh, 
added fo as to faturate it exa@tiy, will de- 
tach every atom of lime from its conneétion. 
Eo:h the inconveniences above-mentioned wiil 
be thus prevented. 2. The feptic acid may 
pofiibly be defeétive or vitiated in fome 
cales. Of this, hewever, we know little ; 
ang the little we know leadsus to be very 
far from believing the acid ingredient of the 
faitvetre ta be muchin fault. That four pro- 
éuct of putrefé€tion is commonly active 
encugh. When flvating at large in an aécial 
Literary and Philfophical Intelligence. 
[Sept. ly 
form, and poifoning the atmofphere with 2 
peftilential taint, its epidemic ravages are 
but too well-known. It woeld feem that 
when held in bondage, and enchained by pot- 
afh, its deftru€tive career was run, and would 
never be begun again. Buc it is a curious 
and admirable fa&, that that pernicious acid, 
which, before its conneétion-with potafh, 
was the chief inftrument of peftilence; 
fhould, in the act of extrication and enlarge- 
ment (deftructive like dying Sampfon) be the 
principal engine of war. As far as the power 
of this age: t goes, it is moftly ftrong enough. 
3. In a cryftallized form, faltpetre, like all 
other falts, contains a quantity of water. 
But this water is isi a latent fate, and not dif- 
coverable by an hygrometer. For all the 
purpofes of touch, the fubftance may be pro 
nounced dry. Ina pure and perfeétlv faturated 
ftate of feptic acid and potafh, there will be 
no attraGtion of water from the furrounding 
air, and confequently fuch faltpetre will not 
attrast moifture, nor caufe dampnefs. in the 
gunpowder into whofe conftitution it enters 
On the whole, Sir, I believe the fault. you 
find with your cannon-powder is to be referred 
to impurity or adulteration in the faltpetre. 
There appears good reafon to conclude, that 
the evil will be remedied by a removal or 
corre€tion of thefe. I therefore recommend 
that great care be taken to refine and cryftallize 
the faltpetre.” 2 . 
Some fevere remarks appear in the fame 
Repofitory, relative to ** the pretended and 
ufelefs difcovery,”” as the editors call it, 
of Dr. Smith’s nitrous fumigation, as @ 
preventive of contagion. 
Vassati Eanpt has fhewn by repeated 
experiments (1.) That metals and their 
oxides, thrownion his eleétrometer, bring 
thither a contrary kind of electricity, the 
metal pofitive electricity, and its oxide 
negative. (2.) That the eleétric fiuid 
does not affect the fluid of the voltaic 
pile, the ation of which is not altered 
by the union of pofitive ele&tricity to the. 
negative pile, nor by another combina- 
tion of electric and Galvanic conductors. 
From thefe and other experiments of the 
fame kind, he has deduced the theory, of © 
Galvanifm, which he explained in the laft 
fitting of his puble experiments at the 
Atheneum of Turin, 
Hu meo cnr, the celebrated traveller, is 
expected ‘n Paris, in September or Oto 
ber. He has promifed to bring with hiw 
many new genera and fpecies of plants ; 
likewife a filiceous fub!tance, analogous 
to the tabafcher of the Eaft-Indies, which 
exits in the knots of a gigantic grami- 
neous plan-, that is confounded with the. 
bawbou. In his letter to Delambres he 
fpeaks of the mk of a wegetable cow, 
a tree fo calied by the Indians, which 
phe when 
