Fusion by the Hydro-oxygen Blowpipe. 45 



pipes, six protrude through the brass casting forming the bottom 

 of the copper case constituting the refrigerator, so as to be equi- 

 distant 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 Jj of an inch in thickness. Those of the larger instru- 

 ments represented by the accompanying engravings were such as 

 to admit wires of ^ th 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 con- 

 verted into a hollow wire ; the edges of the strip being brought 

 into contact reciprocally, so as to leave only an almost impercep- 

 tible crevice. Having drawn one strip of platina in this way, 

 another strip sufficiently wide nearly to enclose it, is to be drawn 

 over that first drawn, care being taken to have the crevices left 

 at the meeting of the edges on contrary sides. The compound 

 hollow wire or tube thus fabricated, is finally to be drawn upon 

 a steel wire of the diameter of the requisite bore. 



making jet-pipes, though more 



as 



refrigerator leaking into the bore. 



Select a very sound and malleable cylinder of platina, of about 

 three-eighths of an inch in thickness, perforate it by drilling in a 

 lathe, so that the perforation may be concentric with the axis. 



an 



employed. In the next place the cylinder may be elongated by 

 the wire-drawing process, until the proper reduction of metallic 

 thickness is effected, the diameter of the bore being prevented 



tion of a steel wire. 



undue 



annealed 



by drawing. For this purpose, a much higher temperature I 

 necessary in the case of platinum, than in that of either copper 



silver, or gold. 



best performed by the hydro-oxy 



If charcoal be used, the greatest care must be taken to have the 



firej 



be 



as 



as 



this metal, it is of course, for that purpose, preferable to gold 

 where great heat is to be resisted. No doubt, by employing pal- 

 ladium to solder the exterior juncture of the double drawn tubes 

 above mentioned, they might answer as well nearly as when con- 

 structed of solid Dlatinum. 



