44 Fusion by the Hydro-oxygen Blowpipe. 



parallel. The tube is then to be subjected to the wire-drawing 

 apparatus, so as to compress the tube on its contents until the 

 draught becomes so hard, as that it cannot be pushed farther 

 without annealing. The stuffed tube thus made is to be cut into 

 segments, in lengths about equal to the diameter, by a fine saw. 

 The surfaces of the sections are to be filed gently with a smooth 

 file. By these means, they appear to the naked eye like the su- 

 perficies of a solid metallic cylinder. Brass caps being fitted on 

 these sections, they are to be interposed by soldering, at the dis- 



tance of a foot or more, into the pipe for supplying the jet. Un- 



der these circumstances, the posterior section becoming hot, may 

 allow the flame to retrocede ; but the anterior section being be- 

 yond the reach of any possible combustion, and remaining cold, 

 will not allow of the retrocession ; and as soon as the flame passes 

 the first section, the operator, being warned, will, of course, close 

 the cock, and subject the posterior section to refrigeration before 

 proceeding again. 



But this plan of operating may be rendered still more secure 

 by interposing a mercury bottle, or other suitable iron vessel, half 

 full of oil of turpentine, between the reservoir and safety tubes, 



as in the arrangement of a Woulfe's bottle. A leaden pipe pro- 



ceeding from the reservoir is, by a gallows screw, attached to an 

 iron tube which descends into the bottle, so as that its orifice 

 may be near the bottom. The leaden pipe communicating 

 through the safety tubes with the jet-pipe, is attached to the neck 

 of the bottle. Thus the gaseous mixture has to bubble through 

 the oil of turpentine in order to proceed through the safety tubes 

 to the jet-pipe. If, while 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 

 mechanical 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 Jive ounces in weight 



For the fusion of either Iridium or Rhodium or masses of Pl a- 

 tinum not exceeding the weight of half an ounce, an instrument 

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

 being such as not to admit a wire larger than the *'* of an inch 

 in diameter. The flame produced by these means was quite 

 sufficient to envelope the mass to which it was applied. 



In fusing any lumps or congeries of platinum, not exceeding 

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

 jets of gas, issuing of course, from as many pipes* Of these 





