40 Hydro-orygen Blowpipe. 
Of the fusion of iridium and rhodium, I have already given 
an account in the Bulletin of the American Philosophical Society, 
which was subsequently embodied in an article in this Journal 
for October last, 1846.* 
It remains now to give an account of the apparatus employed 
in the fusion of platina on a large scale. 
Fig. 1 represents the association of fifteen jet pipes of platinum 
with one large pipe, B, D, at their upper ends, so that their bores 
communicate, by means of an appropriate brass casting, with 
that of the large pipe, the joints secured by hard solder. Their 
lower extremities are made to protrude about half an inch from 
a box, A, of cast brass, their junctures, with the appropriate per- 
forations severally made for them, being secured by silver solder. 
They come out obliquely in a line along one corner of the box, 
an interval of about a quarter of an inch alternating with each 
orifice. By means of flanges, the ‘brass box is secured to a conl- 
ical frustum of copper, fig. 2, so as to form the bottom thereof, 
while the pipe, extending above the copper case, is screwed to a 
hollow cylinder of brass, A, fig. 3, provided with two nozzles 
and gallows screws, g, 2, for the attachment of appropriate hol- 
low knobs, to which pipes are soldered, proceeding from the res- 
ervoirs of oxygen and hydrogen. Cocks are interposed by which 
to regulate the emission of the gases in due proportion. 
In connecting the pipes conveying the gases with the brass 
cylinder, A, fig. 3, care should be taken to attach that conveying 
oxygen to the upper nozzle, while the other, conveying hy: 
gen, should be attached to the lower nozzle ; since, by these means 
their great difference in density tends to promote ture, 
which, evidently, it must be advantageous to effect. 
The object of surrounding the jet pipes with water, by means 
of the copper box,t is to secure them against being heated to 
such a degree as to cause the flame to retrocede and burn within 
them, so as finally to explode within the cylinder, A, 8; &) fig. 3. 
It is preferable to add ice or snow to the water, in order to pre 
vent undue heat. 
Fig. 4 represents a movable platform, A, of cast iron, wholly 
supported upon the point of the iron lever, D, B, which 1s curv 
ed towards the extremity under the platform, so as to point up- 
wards, and to enter a small central conical cavity made for its 
eee 
t Since the engraving was made, I have preferred to use voice boxes, with 
: ower nozzle, @ PPS ie 
communicating with a head of cold water, the other being 5° rer 
ing the whole time that the operation is going on. acai sn UH 
As a support, a brick kaolih is used, having an oblong ellipsoidal depression ° 
the upper face for the reception of the metal to be fused. 
