GEM 
tar, and sifting it through a fine sieve, set it 
by for use; then scrape with a knife a quan- 
tity of the yellow tripela into a sort of powder, 
and afterwards rub it till very fine in a glass 
mortar with a glass pestle. The finer this 
powder is, the finer will be the impression, 
and the. more accurately perfect the cast. 
The artificer might naturally suppose, that 
the best method to obtain a perfectly fine 
powder of this earth, would be by washing it 
in water ; but he must be cautioned against 
this. There is naturally in this yellowish 
tripela a sort of unctuosity, which, when it is 
formed into a mould, keeps its granules toge- 
ther, and gives the whole an uniform glo*sy 
surface; now washing the powder takes away 
this unctuosity; and though it 'renders it 
much finer, ft makes it leave a granulated 
surface, not this smooth one, in the mould ; 
and this must render the surface of the cast 
less smooth. 
When the two tripelas are thus separately 
powdered, the red kind must be mixed with 
so much water as will bring it to the consist- 
ence of paste, so that it may be moulded like 
a lump of dough between the fingers: this 
paste must be put into a small crucible of a 
flat shape, and about half an inch or little 
more in depth, and of such a breadth at the 
surface as is a little more than that ot^ the 
stone whose impression is to be taken. 1 he 
crucible is to be nicely filled with this paste 
lightly pressed down into it, and the surface 
of the paste must be strewed over with the 
fine powder of the yellow tripela not wetted. 
When this is done, the stone of which the 
impression is to be taken must be laid upon 
the surface, and pressed evenly down into the 
paste with a finger and thumb, so as to make 
it give a strong and perfect impression ; the 
tripela is then to be pressed nicely even to 
its sides with the fingers, or with an ivory 
knife. The stone must be thus left a few mo- 
ments, for the humidity of the paste to 
moisten the dry powder ot the yellow tripela 
which is strewed over it; then the stone is to 
be carefully raised by the point of a needle 
fixed in a handle of wood, and the crucible 
being then turned bottom upwards, the stone 
will fall out, and the impression will remain 
very beautifully on the tripela. If the sides of 
the cavity have been injured in the falling out of 
the stone, they maybe repaired, and the cru- 
cible must then be set, for the paste to dry, 
in a place where it will not be incommoded 
by the dust. 
The red tripela, being the more common 
and the cheaper kind, is here made to fill the 
crucible only to save the other, which alone 
is the substance fit for taking the impression. 
When the stone is taken out, it must be ex- 
amined, to see whether any thing is lodged 
in any part of the engraving, because, if there 
is any of the tripela remaining, there will of 
course be so much wanting in the impression. 
When the crucible and paste are dry, a piece 
of glass must be chosen of a proper colour, 
and cut to a size proper for the figure; this 
must be laid over the mould, but in such a 
manner that it shall not touch the figures, 
otherwise it would spoil them. The crucible 
is then to be brought near the furnace by de- 
grees, and gradually heated till it cannot be 
touched without burnisg the fingers; then it 
is to be placed in the furnace under a muffle 
surrounded with charcoal. Several of these 
small crucibles may be placed under one 
GEM 
muffle; and when they are properly dispos- 
ed, the aperture of the muffle should have a 
large piece of burning charcoal put to it, and 
then the operator is to watch the process, and 
see when the glass begins to look bright : 
this is the signal of its being fit to receive the 
impression. The crucible is then to be 
taken out of the fi*e, and the hot glass must 
be pressed down upon the mould with an 
iron instrument, to make it receive the re- 
gular impression ; as soon as this is done, the 
crucible is to be set by the side of the fur- 
nace out of the way of the wind, that it may 
cool gradually without breaking. When it 
is cold, the glass is to be taken out, and its 
edges should be grated round with pincers, 
in order (o prevent its Hying afterwards, which 
is an accident that sometimes happens when 
this caution has been omitted, especially 
when the glass is naturally tender. The dif- 
ferent coloured glasses are of different de- 
grees of hardness, according to their compo- 
sition; but the hardest to melt are always the 
best for this purpose, and this is known by a 
few trials. 
If it is desired to copy a stone in relief 
which is naturally in creux, or to take one in 
creux which is naturally in relief, there needs 
no more than to take an impression, first in 
wax or sulphur, and to mould that upon the 
paste of tripela instead of the stone itself; 
then proceeding in the manner before direct- 
ed, the process will have the desired effect. 
A still more simple and easy method is by 
taking the casts in gypsum, or plaister of 
Paris, as it is commonly called. For this 
purpose the gypsum must be finely pulveriz- 
ed, and then mixed with clear water to the 
consistence of thick cream. This is poured 
upon the face of the gem or seal of which the 
impression is wanted, and which must be 
previously moistened with oil to facilitate the 
separation of the cast; and in order to confine 
the liquid 'plaister it is only necessary to pin a 
slip of oiled paper round the sides of the seal 
by way of a cap or rim. When the plaister is 
dry, it is to be taken off, and set before the 
mouth of the furnace, in order to free it en- 
tirely from moisture, when it is fit to be used 
as a matrix in the same way as that formed 
with the tripoli earths. Only no crucible or 
other receptacle is at all necessary, the casts 
being formed like so many small cakes half 
an inch thick, and then put into the furnace 
with the bits of glass upon thefti. The glass, 
after coming to a proper heat, is pressed 
down upon the mould with an iron spatula to* 
receive the desired impression, the pressure 
required being more or less, according to the 
size ofthe stone. t This method has been long 
practised very successfully, and with no small 
emolument, by that ingenious seal-engraver, 
Mr. Deuchar of Edinburgh. The only re- 
spect in which it is inferior to the other more 
operose anti expensive methods, consists in 
the chance of air-bubbles arising in pouring 
on the plaister; which chance, however, is less 
in proportion to the fineness of the gypsum 
employed. When air-bubbles do occur, the 
casts may be laid aside, as it is so easy to re- 
place them. 
Of all the artists and ingenious men who 
have taken impressions of engraved gems in 
sulphur and in paste, no one seems to have 
carried that art to such perfection as Mr. 
James Tassie, a native of Glasgow, but who 
latterly resided in, London, 
L 
GEN 829 
Mr. Tassie, profiting by the former publi- 
cations of this sort, ana by expence, industry, 
and access to many cabinets in England and 
other kingdoms to which former artists had 
not obtained admission, increased bis collec- 
tion of impressions of ancient and modern 
gems to the number of above 15,000 articles. 
It is the greatest collection of this kind that 
ever existed, and serves for all the purposes 
of artists, antiquaries, scholars, men of taste, 
and even philosophers. The great demand 
for his pastes was perhaps owing in the be- 
ginning to the London jewellers, who intro, 
duced them into fashion by setting them in 
rings, seals, bracelets, necklaces, and other 
trinkets. 
The reputation of this collection having 
reached the empress of Russia, she was pleas- 
ed to order a complete set; which, being ac- 
cordingly executed in the best and most du- 
rable manner, were arranged in elegant cabi- 
nets, and are now placed in the noble apart- 
ments of her imperial majesty’s superb palace 
at C’zarsko Zelo. 
Mr. Tassie, in executing this commission,, 
availed himself of all the advantages which 
the improved state of chemistry, the various 
ornamental arts, and the knowledge of the 
age, seemed to afford. The impressions were 
taken in a beautiful white enamel composi- 
tion, which is not subject to shrink or form 
air-bladders, which emits lire when struck 
with steel, and takes a fine polish, and which 
shows every stroke and touch of the artist in 
higher perfection than any other substance. 
When the colours, mixed colours, and nature 
of the respective originals, could be ascer- 
tained, they were imitated as completely as 
art can imitate them ; insomuch that many of 
the paste intaglios andcameoes in this collec- 
tion are such faithful imitations, that artists 
themselves have owned they could hardly be 
distinguished from the originals. And when 
the colour and nature of the gems could not 
be authenticated, the pastes were executed 
in agreeable, and chiefly transparent, colours; 
constant attention being bestowed to pre- 
serve the outlines, extremities, attributes, and 
Inscriptions. 
GENDARMERIE, Fr. TI»e gendarmerie 
was a select body ot cavalry that look prece- 
dence of every regiment of horse in the 
French service, and ranked immediately after 
the king’s household. The reputation of tire 
gendarmerie was so great, and its services so 
well estimated by the king of France, that 
when the emperor Charles V. in 1552, sent a, 
formal embassy to the court of Versailles to 
request a loan of money, and the assistance 
ofthe gendarmerie to enable him to repulse 
the Turks; Francis I. returned the following, 
answer: “ With respect to the first object of 
your mission, (addressing himself to the am- 
bassador) I am not a banker ; and with regard 
to the other, as my gendarmerie is the arm 
which supports my sceptre, I never expose it 
to danger, without myself sharing its fatigue 
arid glory.” 
The uniform ofthe gendarmerie, as well as 
of the light cavalry, under the old French 
government, was scarlet, with facings of the 
same colour. The coat was formerly more- 
or less laced with silver, according to the- 
king’s pleasure. A short period before the- 
revolution, it was only laced on the cuff. 
The waistcoatwas of buff leather, and tire ba% 
