Hydro-Oxygen Blowpipe for the Fusion of Platinum. 365 



this process is going on, the flame should, by retrocession, 

 reach the cavity of the bottle, exploding in contact with the 

 turpentine, a compound is formed, which is, per se, inexplosive 

 from the excess of carbonaceous matter. Meanwhile the 

 shock, acting on the surface of the oil, drives it into the bore 

 of the iron tube, and thus, both by its chemical and mecha- 

 nical influence, renders it utterly impossible that the flame 

 should reach the cavity of the reservoir. 



Apparatus for the Fusion of Iridium or Rhodium or masses of 

 Platinum less than five ounces in weight. 



For the fusion of either iridium or rhodium or masses of 

 platinum not exceeding the weight of half an ounce, an instru- 

 ment with three jets has been employed, the bore of each jet- 

 pipe being such as not to admit a wire larger than the ^^^d 

 of an inch in diameter. The flame produced by these means 

 was quite sufficient to envelope the mass to which it was ap- 

 plied. 



In fusing any lumps or congeries of platinum, not exceed- 

 ing five ounces, an instrument has been used capable of giving 

 seven jets of gas, issuing of course from as many pipes. Of 

 these pipes, six protrude through the brass casting forming 

 the bottom of the copper case constituting the refrigerator, so 

 as to be equidistant from each other upon a circumference of 

 three-fourths of an inch in diameter, the seventh protruding 

 from the centre. The bores of these jets are such as not to 

 admit a wire larger than ^^2"^ of an inch in thickness. Those 

 of the larger instruments, represented by the accompanying 

 engravings, were such as to admit wires of J^^h of an inch in 

 thickness. 



The jet-pipes may be made by the following process : — A 

 thin strip of sheet metal, somewhat wider than the length of 

 the circumference required in the proposed pipe, after being 

 roughly turned about a wire so as to form an imperfect tube, 

 is drawn through several suitable holes in a steel plate, as in 

 the wire-drawer's process. Under this treatment the strip 

 becomes converted into a hollow wire ; the edges of the strip 

 being brought into contact reciprocally, so as to leave only an 

 almost imperceptible crevice. Having drawn one strip of 

 platina in this way, another strip sufficiently wide nearly to 

 inclose it is to be drawn over that first drawn, care being taken 

 to have the crevices left at the meeting of the edges on con- 

 trary sides. The compound hollow wire or tube thus fabri- 

 cated, is finally to be drawn upon a steel wire of the diameter 

 of the requisite bore. 



The following method of making jet-pipes, though more 



