234 Mr. Cooper’s Lamp Furnace, 
receiver shewn at fig.9; it is about twelve inches long, and one inch 
in diameter, and being filled with mercury and hung over a basin 
is ready for use. When containing gas, its quantity is estimated 
by the graduated scale on the tube, care being taken previously to 
compensate for any difference of mercurial pressure by inserting the 
long funnel and cork, fig. 10, into the mouth of the receiver, and 
pouring mercury into the funnel until it is level with that in the re= 
ceiver. It is easy afterwards to admit water or solution of potash 
into the receiver to absorb the carbonic acid, and leave the nitrogen. 
The oxide of copper required in using this instrument may be 
procured either by burning the residuum of verdigris which has been 
used in the preparation of acetic acid, or by heating plates of copper 
with access of air, and quenching them in water. Great care 
should be taken that the oxide be pure, and it should be pulverised 
and heated ina crucible, stirring at the same time. It may then be 
sifted, and the different portions preserved apart. The tube used 
should be of crown or green-bottle glass, fourteen to fifteen inches 
long, (not so long if the separate bent end piece is used,) and from 
one to two tenths of an inch internal diameter; it should be clean and 
dry, one end should be sealed up by a blow-pipe, and then it may be 
balanced. The substance if volatile is now to be introduced, if 
solid it may be shaken to the bottom, if fluid it is to be poured in 
by the funnel, fig. 7. The quantity of substance is then to be 
ascertained, and a portion of cold oxide of copper introduced, suf- 
ficient to absorb the substance if fluid, and cover it about a quarter 
of an inch; after which recently heated and still warm oxide is to 
be added to the proper height. Then a portion of recently 
ignited asbestos is introduced and pressed rather lightly on to the 
oxide, and occupying from one to two inches. The tube, with its 
contents, is then to be balanced again, after which itis to be enve= 
loped in the copper foil, (care being taken that the foil does not 
cover the part containing the asbestos,) and the end piece with its 
caoutchouc tube is to be fastened on. : 
The tube is then to be arranged as in the figure, and heat applied ; 
the lamps are to haye but short wicks, so that the top of the flame 
