Hydro-Oxygen Blowpipe for the Fusion of Platinum. 359 



cylinder A, fig. 3, care should be taken to attach that con- 

 veying oxygen to the upper nozzle, while the other, conveying 

 hydrogen, 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*, 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, 

 gg, fig. 3. It is preferable to add ice or snow to the water, 

 in order to prevent undue heat. 



Fig, 4 represents a moveable platform A, of cast iron, wholly 

 supported upon the point of the iron lever D B, which is 

 curved towards the extremity under the platform, so as to 

 point upwards, and to enter a small central conical cavity 

 made for its reception. The lever is supported by a universal 

 joint upon the fulcrum C, so that by means of a sliding weight 

 at one end, the platform and its appurtenances are counter- 

 poised at the other. The platform is kept in a horizontal 

 position by the cannon-ball, supported in a sort of iron stirrup 

 terminating in a ring, in which the ball is placed. Upon the 

 platform is situated an iron pan with a handle holding the 

 brick, on a cavity in which, as already mentioned, the metal 

 is supported. The apparatus being duly prepared and con- 

 nected with the supply-pipes, the hydrogen is first allowed to 

 escape and then the oxygen, until the ignition has attained 

 apparently a maximum. The accomplishment of this object 

 may of course require the adjustment of either cock several 

 times, especially where there is any decline in the pressure 

 either of the one or the other gas in its appropriate reservoir. 



By means of the handles of the lever and of the pan, the 

 operator is enabled to bring the metal into the position most 

 favourable for the influence of the iieat, while his hands and 

 face are sufficiently remote to render the process supportable. 

 In fusing any quantity, not being more than four ounces, the 

 platform may be dispensed with, the handle of the pan being 

 held in one hand of the operator, while by the other the cocks 

 may be adjusted. 



When the blowpipe of fifteen jets, or any larger, may be 



* Since the engraving was made, I have preferred to use water-tight 

 boxes, with gallows-screws and nozzles, situated one near the bottom on 

 one side, the other on the opposite side near the top. By means of the 

 lower nozzle, a pipe is attached, 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 during the whole time that the opera^ 

 tion is going on, 



As a support, a brick kaolin is used, having an oblong ellipsoidal depres- 

 sion on the upper face for the reception of the metal to he fused. 



