1817.] during the Year 1816. 7 
to support vessels containing gas. Opposite to three indentations on 
the edge of the trough are three holes in one of the shelves, into 
which the beak of retorts liberating gas are to be introduced, ora 
sliding shelf and apertures may be fitted across the cavity for the 
same purpose. The gazometer is at one end, and sunk below the 
level of the trough. It is capable of containing 50 cubic inches. 
A tube connected with the gazometer at the lower part is made to 
ascend, and passing up through the mercury in a corner of the 
trough, at about an inch above, it bends down again. and termi- 
nates between its surface. If gas is contained in the gazometer, it 
may be transferred to air jars in the trough, by filling them with 
mercury, placing them over the end of this bent tube, and giving 
pressure to the gazometer. “The air will pass from the gazometer 
along the tube into the jar. By the bend in the tube, the mercury 
is prevented from passing into the lower part of the gazometer, 
while at the same time the gas is allowed a free passage. All in- 
convenience is prevented by means of a stop-cock, which shuts off 
the communication between the receiver and the trough, preventing 
as the same time the escape of air from the gazometer, and of mer- 
cury into it. A sliding shelf is fixed beneath the trough to support 
a spirit lamp under a retort, or for other purposes. A detonating 
tube and spring are also attached to the apparatus by a clamp and 
screws, and may be fixed on any side of the trough. The whole 
apparatus is of iron, excepting sometimes the pillars which support 
it, and which may be of brass. It is not more than 18 inches in 
length and height. It is placed in a large japanned tray to collect 
scattered mercury. 
2. Mineralogists are indebted to Mr. Brooke for a very ingenious 
and valuable improvement of the common blow-pipe. A descrip- 
tion of it by Mr. Brooke himself will be found in the Annals, vii. 
367. It consists of a close box, into which air is condensed by 
means of a syringe. From this box the air is allowed to rush upon 
the flame of a lamp or candle, and thus produces all the effect of 
the common blow-pipe, while both the hands and mouth are left 
disengaged. 
By means of this new blow-pipe filled with a mixture of two 
volumes hydrogen and one volume oxygen gas, some very curious 
and important experiments have been made by Dr. Clarke, an ac- 
count of which he has published, partly in the Journal of the Royal 
Institution, iii, 104, and partly in the Annals, viii. 357. He found 
the heat produced in this way capable of fusing all substances tried, 
excepting only charcoal and plumbago. All the most refractory 
stones, ihe earths, namely, lime, barytes, strontian, magnesia, 
alumina, and silica, were melted into glass, slag, or enamel. But 
the most unexpected result was the reduction of barytes and stron- 
tian into their metallic bases. Of these metals thus obtained I have 
seen specimens. ‘They were white, had a silvery lustre, and a spe- 
cific gravity exceeding 4. But they were not in a state of pertect 
