
indeed, much evidence might be adduced 
“to fhew that it was not formerly known 
in that country. 
March 12, s800. D. F. 
=a 
For the Monthly Magazine. 
ANALYsi5 of all the perntanently valuable 
Papers which have appeared in the 
JourNaL DE Puysigque, from its 
Commencement io the prefent Tune; con- 
tinued from our lafi Magazine, page 147. 

PREPARATION OF CoOAL-BALLS ‘OR 
BRICKS FORFUEL. ByM. CARREY. 
Fourn. de Phyf. I. 433. 
T has long been cuttomary im the pro- 
vince of Hainault, and throughout the 
whole of Flanders, toconvert, by a very 
_fmple procefs, the fmall duft of pit-coal, 
whichis generally thrown away, into a very 
valuable article of fuel, by moulding it up 
with clay into bricks or balls, of the fize 
©f a twelve pound cannon ball. For this 
purpofe the fmall-coal is fifted,and thelarger 
syagments are reduced into acoarfe powder 
3n a mortar, which is then mixed with the 
general mafs. A. tub is then 4lled about 
one third withany common tenacious clay, 
and a quantity of water poured upon it ; 
when the whole is well mixed and is of 
the confiftence of thick cream, a hole is 
madein the heap of coal-flack, and the 
clay poured in: the coal and clay are then 
~firred together with a rake, or any other 
convenient inftrument, till the parts are 
perfectly incorporated: of this mafs bricks 
‘may be made in the ufual manner, or it 
may be formed into balls by the hand: 
thele after being dried, under cover, fora 
fortnight or three weeks, according to the 
weather, may be either uled immediately 
as fuel, or fiacked for future confumption. 
By this preparation not only the coal re- 
fufe is turned to advantage, but the quan- 
tity of heat produced, and the length of 
3ts duration, is fo much increafed that a 
bufhel of thefe balls will make a> hotter 
fire and laft longer than the fame meafure 
of common coal in the proportion of eight 
to five. é 
Remarks—The above method has been 
_ Jong practifed in this country, in Nor- 
thamptonfhire, Oxfordfhire, and probably 
feveral other counties where coals are 
fearce: it appears alfo by a public adver- 
tifement, that a fimilar manufactory has 
Tately been eftablifhed in London. It ison 
every account defirable that the greater 
part of the imall-coal fhould be difpofed of 
in this way; and the mills at prefent in 
ule for grinding brick-clay, will ferve ad- 
Analyfis of Papers in the 
we 
mirably well to mix the materials. In 
ufing thefe balls, the moft convenient way 
is, firft to make a fire of commen coal, fo 
as to half fiJl the grate, and then to pile 
the balls a little above the top bar. A 
common grate thus charged will require no 
rns and will need no frefh fuel for ten 
ours. 
Fournal de Phyfique. 
Preparatin of Wuite Copper for SpPe- 
CULUMs, Mirrors, &c. 
It is well known that this mixed metal 
is an alloy of copper and arfenic ; but con-= 
fiderable difficulties have occurred in unit- 
ing the two, fince arfenic is readily vola- 
tilized at the temperature required for 
fufing copper. A very fimple and effec- 
tual way, however, of obviating this dif- 
ficulty has- been difcovered by an artift of 
Grenoble. When the copper is in com- 
plete fufion, a quantity of arfenic is put 
into’ an enameller’s pot, and the mouth 
{topped up with a plug of paper; the pot 
being then inverted in the copper, the ar- 
fenical fumes have no way of efcape but 
by paffing through the whole fubftance of 
the copper, which thus, after repeating 
the operation two or three times, becomes 
hard, of a filvery white, and capable of an 
exquilfite polifh. - 
Remarks—It would be a confiderable 
improvement in this 
arfenic with about half its weight of tal- 
low or oil, by which means probably a 
rocefs to mix the 
fingle dofe of arfenic would be fufficient. ” 
It is alfo a neceffary caution to warm the 
enameller’s pot before it is inverted in the 
melted copper, otherwife there will be 
fome rifk of an explofion. 
Preparation of different hinds of VaR- 
NisH. ByM. WarTin. 
Fourn. de Phyf. IT. 382. : 
x. Ina pint of fpirit of wine put half a 
pound of fandarach, and two ounces of 
ou maftich in tears ; when thele are per- 
e&tly diffolved, incorporate- thoroughly » 
_with the mixture four ounces of Venice 
turpentine. 
2. Diffolvein a pint of fpirit of wine, 
half a pound of fandarach, two ounces of 
fhell-lac and four ounces of colophony ; 
when the folution is complete, add fix 
ounces of Venice turpentine. For a red 
varnifh, diminifh the quantity of fanda-— 
rach, increafe that of the fhell-lac, and add 
dragon’s-blood. 
3. Copal varnifh. 
Melt in a perfectly clean veffel by a 9 
dd. 
flow heat a pound of clear copal; to this a 
from one to two quarts of drying hintes 
7 oils 
