for procnrhig jiure Platinum. 251 



17. As platinum can be fused only in small masses at a 

 time, and at a flame supplied with oxygen gas, or the compound 

 flame of oxygen and hydrogen, it cannot be melted on the 

 large scale like most others. However, chemists have suc- 

 ceeded in forming this metal into ingots of a very considerable 

 weight, by uniting the particles with strong pressure at a very 

 high temperature. For this purpose, a certain quantity of pla- 

 tinum, resulting from the calcination of the triple ammoniacal 

 salt, is compressed in a crucible ; then more is successively in- 

 troduced, even to the amount of 20 or 30 pounds. The cru- 

 cible is then covered, and heated to whiteness. The platinum is 

 now transferred as speedily as possible into a square steel ma- 

 trix, (a strong hoop of steel, jointed, would answer equally well) 

 and capable of opening into two pieces by means of hinges. On 

 the top of the ignited mass, a steel mandril, adapted to the 

 cavity of the matrix, is to be applied, which is to be rapidly 

 driven home, by three or four blows of a strong coining screw- 

 press. By this powerful pressure, which the spongy platinum 

 experiences at a white heat, it diminishes greatly in bulk, and 

 its particles already acquire a pretty strong cohesion. The ma- 

 trix, or collar, is opened, the mass of platinum is removed to 

 be heated anew in a crucible to a red-white heat, at a fire acted 

 on by two good bellows. It is again introduced with the utmost 

 celerity into the matrix, where it receives five or six blows of the 

 fly-press. In the second operation, all the particles of the pla- 

 tinum are sufficiently approximated to form a homogenous 

 mass, which may be thenceforth heated, without inconvenience, 

 among naked charcoal, giving it the greatest possible heat, and 

 condensing, with two blows of the press, each face of the ingot. 

 In thus transferring the mass of platinum successively, from the 

 forge to the press about thirty times, we obtain an ingot per- 

 fectly sound, possessed of great malleability and ductility. Pla- 

 tinum thus made into ingots, is delivered to the workmen, who 

 fashion it like gold and silver; that is to say, all the pieces are 

 stretched at first under the rolling-press, and then fashioned by 

 the hammer, taking care to anneal it from time to time. Thus 

 are prepared, in France, the great masses of platinum, with 

 Si 



