522 On the Phenomenon 
tering the point of a pen-knife under one 
fide, and it will eafily rife off the medal in 
a clear, tranfparent, and perfe&t refem- 
blance of the whole, and every the minut- 
eft part of it. 
Improved method of taking off eaf's 
Srom coins, Gc.—By forming a coat or 
layer of thin metal over the plafter of Pa- 
ris, it gives it a confiderable defence.— 
Tin is the cheapeit and mot convenient 
metal for the purpofe, as it is fufficiently 
flexible, and at the fame.time very much 
refembles filver. - The tin-foil ufed for 
filvering ldok ing-elaliee will anfwer very 
well. It fhould he laid over the medal or 
coin intended to be taken off, and then 
rubbed either with a brufh, the pointof a 
fkewer, or 2 pin, till it has received per- 
fectly the impreflion of the medal: the 
tin-foil fhould now be pared of round the 
edge of the medal, till it is broughi tothe 
fame Hee ati The meda} mutt then 
be reverfed, and the tin-foil will drop of 
into a chip box or mould ready to receive’ 
it, the concave fide of the foil, or that 
which is laid on the face of the medal, 
being uppermoft; upon this pour: platter 
of Paris made in the ufual manner, and 
when dry, the caft figure may be taken out 
of the box or inauld, with the tin-foil 
fticking on the plafter, the convex fide 
being now uppermoft again, in which po- 
fition itis to be kept in the cabinet after 
it becomes dry. To have an imprefiion 
7 perfect, the thinneft tin-foil fhould 
be made ufe of. 
The impreffions taken in the foregoing 
manner almoft equal filver medals in beau- 
ty, and are very durable. If the box or 
mould be rather larger than the impreffion 
of tin-foil, the plafter, when poured on, 
runs round its edges, and forms a kind 
of white frame or circular border round 
the foil, whence the new-made medal ap- 
pears more neat and beautiful. 
If this tin-foil be gilt with gold-teaf, 
by means of thin ilrn slafs-glue, the me- 
dal will refemble gold. 
Hull, 
May 13, 1806. 
Wm. Preus, 
P.S. Ithould feel myfeif obliged to any 
of your learned correfpondents for anfwers to 
the following queries, through the medium 
of your Magazine, as by the fame means I 
fhall have no ebje€tions to anfwer any that 
lies in my power, as I am pofleiled of hun- 
dreds of curivus and ufeful receipts, of va- 
tious ‘kinds. 
x. The method of removing the yellow- 
nefs upon marble about fire-places, as allo 
the yellow {pots or iron moulds ppon marble 
hearths 2: 
-than fome fubftance generated 
7 
(July.t, 
2. The method of mending China by bura- 
ing? 
3. To make an indelible ink for marking 
linen with a pen? 
4. The method of making tranfoarent co- 
lours, for painting the glaffes or flides of ma- 
gic lanterns? 
of meteoric Stones. 
eee 
Lo the Editor of the etl Magazine. 
SIR, 
DN OrHiNG. has fo ital petplexed 
the naturalift as the phenomenon of 
meteoric ftones. Every theory of their 
origin is at beft improbable, and we have 
only to chufe that which is the leafi fo.— 
he explication of M. Izarn, that thefe 
fiones are formed in the atmofphere, 
though the mott abfurd ef all opinions, is 
not, nowever, new. Dr. Wallace, in his. 
“* Account of the Hflands of Orkney,” 
Lendon, 1760, has the foilowing paffage, 
‘which, no doabt, refers to a met a 
{tone :— 
‘s The air and clouds here, by the ope- 
ration of the fun, do fometimes generate_ 
everal things; as {ome years fince, fome 
fifhermen fiihing half a league from land, 
over againit Copinfha, i in a fair day, there 
fell down from the air a ftone about the 
bignels of a foot-ball, which fell in the 
middle of the boat, and fprung a leak, to 
the great danger of the lives of the men . 
that were int, which could be no other | 
in the 
clouds. Tne fione was like condenfed or 
petrified clay, and was a long time in = 
cuftody of Captain Andrew Dick, 
that time Steward of the country ; cia 
Captain Dick, who is yet alive, told me 
he ere it to the late Earl ef Glencairn.” 
—Pagces 3 and 4, 
The origmal M.S. of Waliace’s ie. 
couct of Orkney (new before me) is dat- 
ed in 1684, and there is this variation in 
it from the adove quotation, ** The air 
and clouds here, by the operation of the 
fun, doe fometym generat feverall bir 
é.g. absut eight or nyn years agoe, tome 
mm 1,7” ec. 
This fone, therefore, fH in oe or 
1676. But the ufual explofion and light of. 
meteoric flones either was not noticed or 
did not take place in this inftance. The ap~ 
pearance of ** condenfed or petrified clay”” 
is quite characteriftic of thefe fubftances. 
To maintain that thefe 4ones are formed 
in the atmofphere, we muft firft prove that 
the atmofphere contains the component 
parts—filex, iron, nickel, and magnefia. 
In {pite of our extenfive knowledge of 
mineralogy, there has’not been difcovered 
on our gicbe any rock fimilar to thefe 
flLonese ’ 
