348 
topaz, and to cut ordinary glafs like a 
diamond, we are warranted to conclude, 
that though they did not derive all the 
advantages that we dofrom that elegant 
fubftance, they contrived, neverthelefs, 
to give ita degree of perfeétion, which 
we are utterly unable to attain. 
Among the many inftruments ufed by 
the ancients, and contained in this cu- 
Tious cabinet, are waxen tablets, with 
fiyles to wrice upon them, and a very 
{mall ivory implement, much refembling 
afaw, for the purpofe of erafing cha- 
racters, and preparing the wax to re- 
ceive new impreifions. But amongthem 
all, there is perhaps notlring more wor- 
thy of notice, than feveral fignatures of 
Romans, cut at full length, upon bronze, 
toenable them to fign their names with 
greater expedition. How aftonifhing, 
that they fhould thus have held the art 
of printing in their hands, without ap- 
plying it-to more.important purpofes ! 
Upon the whole, the antiquities of 
which I have been fpeaking, appear to 
me fo highly interefting, that, when 
joined to the curious objeéts of natural 
hiftory that exift in the vicinity of Na- 
ples, I thmk them a fufiicient reward 
for the fatigue and expence of a journey 
to Italy, provided the traveller have a 
tafte for the remains of old times, for 
grand natural objects, and for the ele- 
gant arts. 

To the Editor of ihe Monthly Magazine. 
SIRs 
THE following extract from a letter of 
HUMBOLDT, a celebrated German 
chemift, which appeared lately in the 
Phyfical Journal, publifhed by Gren, 
contains fome new experiments relative to 
the diferent impreffions excited by the ivi- 
tation of meials on tbe organs of animals. 
This curious fubject, which, as an art, has, 
with foreign chemifts, affumed the name 
of Galvanifm, from GALVAN], a learned 
Italian, the firft who undertook experi- 
ments of this nature, will not, I pre- 
fume, prove unacceptable to the Englifh 
public, through the medium of your re- 
{pectable Mifcellany. it may be necef- 
fary to premife, that the experiments de- 
{cribed in this letter are introduced fome- 
what abruptly, being the fequel to fome 
preceding ones, made by Humboldt, and 
which he propofes to colleét and pub- 
ith, ina larger work on the fubjeét. 
Difcourfing one day with a friend on 
the effets produced by Galvanifm on 
himfelf{—Nothing, he fays, aftonifhed 
him mere, than te oblerve on his back, 
New Science of Galvanifm. 
: wafhing. 
[Mays 
the appearance of a ferous and lymphati 
humour. Of what nature, then, he ex- 
claims, is the ftimulant which has thus, 
ina few feconds, altered the nature of 
the veffels; made them concur to excite 
humours, which, as foon as they touch 
the epidermis, produce a fudden inflam- 
mation, and mark their paflage by a red= 
nefs which lafts for hours together ? 
The relation of this fame experiment 
isone of the moft interefting articles in 
the letter. ; 
He goes on to inform us, that he had 
laid a couple of veficatory plafters on the 
deltoid mufcle of each fhoulder. The 
blifer of the lef: having been opened, 
there iffued out of it a liquor; which left 
nothing but a fhining matter on the fkin, 
and which was inftantly rubbed off by 
The wound of this was after- 
wards dried up, by way of precaution, 
left the acrid humour which the Galvya- 
nic irritation would produce, fhould be 
miftaken for the effeét produced by an 
idiofyncrafis of the veflels. The Galva- 
nic operation was then performed on the 
wound, by means of zinc and filver ; from 
which, as foon as done, the ferous humour 
iffued out in abundance; in a few 
feconds, the colour of this humour be- 
came vifibly darkifh, and~ left, on the 
parts of the fkin which it paffed over, 
traces of a brownifh-red inflammatory 
matter. The humour having defcended 
towards the pit of the ftomach, and cols 
leted'itfelf there, produced a rednefs on 
that part, more than an inch in furface ; 
and, being afterwards laid upon the epi- 
dermis, it there alfo left fpots, which, 
after having. been wafhed, appeared to 
be of a bluith-red. The parts inflamed 
having been inadvertently wafhed with 
cold water, {welled up fo much in mag- 
nitude and colour, that M. Humboldt, 
asweil as his phyfician, Dr. Schalleru, 
who was an affiftant to him in thefe ex- 
periments, conceived, at firft, much in- 
quietude from the circumftance. 
M. Humboldt does not take upon him 
to determine the nature of the fluid 
which produced fuch aftonithing ‘effeéts ; 
but rather makes it his bufineis to cir- 
cumf{cribe the phenomena which occurred _ 
within the real circumftances which oc- 
cafioned them; he fagacioufly varies the 
preparations; notes attentively all the 
refults; and, being affured “that the 
caufe of Galvanifm can only be fucceff- 
fully afcertained by obferving the pro- 
portionate degrees in which the chain 
of metals irritates, or otherwife, he is 
enabled to extend his field of obfervation, 
by 
