oj rendering Platina malleable. 5 



liable to bend, to a strong wooden bench CD. The bar is 

 connected by a pivot at its extremity A, with the lever AFG. 

 An h'on rod FH, which turns at its two extremities upon the 

 pivots F and H, proceeds from the lever at F, and, as the 

 lever descends, propells forward the carriage I, which slides 

 along the bar. A stopper or block being placed in the vacant 

 space I^, the carriage communicates motion to the cradle klm, 

 which is also made to slide along the bar, and carries the bai'- 

 rel N, which lies upon -iie cradle, straight against the piston 

 O, which rests by its end against P, a pi'ojection in the further 

 extremity of the bar. 



The weight, which in this machine, when the angle of the 

 lever's elevation is small, will keep the power, applied vertically 

 at the extremity of the lever, in equilihrio = that power x 



AFrAF+FHI ^ cotan. of the angle of the lever's elevation; 



which expression, in the case of the press actually used, be- 

 comes, power X 5 . cotan. of the angle of the lever's elevation. 

 This expression, 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 quasi 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 forin 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 fire, 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 2i 

 inches above the grate of the furnace, 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 re- 

 fractory crucible ware, resting at its open end upon the layer 

 of sand ; and care is to be taken tliat the sides of the pot do 

 not toucii the cake. 



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

 the usual defect of this metal in its manufactured sUite, it is 



essential 



