40 Hydro-oxygen Blowpipe. 



Of the fusion of iridium and rhodium, I hare already given 

 an account in the Bulletin of the American Philosophical Society r 

 which was subsequently embodied in an article in this Journal 

 for October last, 184G * 



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 comer 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 com- 

 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, g, 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 hydro- 

 gen, should be attached to the lower nozzle ; since, by these means 

 their great difference in density tends to promote admixture, 

 which, evidently, it must be advantageous to effect. 



The object of surrounding the jet pipes with water, by means 

 of the copper box,f 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, g, g, 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 is 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 



* Since published in the Revue Sciontifique at Paris. 



t Since the engraving was made, 1 have preferred to use water-tight boxes, with 

 gallows screws and nozzles, situated one nf ar the bottom on one side, the other on 

 the opposite side near the lop. By means of the lower nozzle, a pipe is at- 

 tached, communicating with a head of cold water, the other being so situated as 

 to carry the water into a waste pipe, or large tub ; a circulation may be kept up dur- 

 ing the whole time that the operation is going on. 



As a support, a brick kaolin is used, having an oblong ellipsoidal depression on 

 the upper face for the reception of the metal to be fused. 



