OF RENDERING PLATINA MALLEABLE. $ 



sion, at an elevation of 5°, becomes nearly 60 X power, and at an elevation of 

 1°, becomes nearly 300 X power ; and when the lever becomes horizontal, the 

 multiplier of the power becomes guasi infinite. This explanation will be suf- 

 ficient to show the mechanical advantage with which, by means of this press, 

 the weight of the operator, acting on the end of the lever, will be made to 

 bear against the area of the section of the barrel, a circle little more than an 

 inch in diameter. 



After compression, which is to be carried to the utmost limit possible, the 

 stopper at the extremity being taken out, the cake of platina will easily be 

 removed, owing to the conical form of the barrel ; and being now so hard 

 and firm that it may be handled without danger of breaking, it is to be placed 

 upon a charcoal fii'C, and there heated to redness, in order to drive off moisture, 

 burn off grease, and give to it a firmer degree of cohesion. 



The cake is next to be heated in a wind-furnace ; and for this purpose is 

 to be raised upon an earthen stand about 2^ inches above the grate of the fur- 

 nace, the stand being strown over with a layer of clean quartzose sand, on 

 which the cake is to be placed, standing upright on one of its ends. It is then 

 to be covered with an inverted cylindrical pot, of the most refractory crucible 

 ware, resting at its open end upon the layer of sand ; and care is to be taken 

 that the sides of the pot do not touch the cake. 



To prevent the blistering of the platina by heat, which is the usual defect 

 of this metal in its manufactured state, it is essential to expose the cake to the 

 most intense heat that a wind-furnace can be made to receive, more intense 

 than the platina can well be required to bear under any subsequent treat- 

 ment ; so that all impurities may be totally driven off, which any lower tem- 

 perature might otherwise render volatile. The furnace is to be fed with Staf- 

 fordsliire coke, and the action of the fire is to be continued for about twenty 

 minutes from the time of lighting it, a breathing heat being maintained during 

 the last four or five minutes. 



The cake is now to be removed from the furnace, and being placed upright 

 upon an anvil, is to be struck, while hot, on the top, with a heavy hanmier, so as 

 at one heating effectually to close the metal. If in this process of forging, the 

 cylinder should become bent, it should on no account be hammered on the 

 side, by which treatment it would be cracked irremediably; but must be 



