from the Ores of Platinum. 175 
of platinum thus obtained, is to be reduced by strong calcination 
in a crucible, observing the precautions already indicated. The 
pure platinuin remains in the crucible, under the form of a greyish- 
coloured spongy mass, which acquires metallic lustre by friction 
against any hard body. 
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 succeeded 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 platinum, resulting from 
the calcination of the triple ammoniacal salt, is compressed in 
a crucible; then more is successively introduced, even to the 
amount of 20 or 30 pounds. ‘The crucible is then covered, and 
heated to whiteness. The platinum is now transferred as speedily 
as possible into a square steel matrix (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 ap- 
plied, 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 di- 
minishes greatly in bulk, and its particles already acquire a pretty 
strong cohesion. The matrix 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 opera- 
' tion, all the particles of the platinum are sufficiently approxi- 
mated to form a homogeneous mass, which may be thenceforth 
heated, without inconvenience, among naked charcval, 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 au ingot perfectly sound, possessed of great 
malleability and ductility. Platinum 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 totime. Thus are prepared, 1n France, the 
great masses of platinum, with which are fabricated the large 
alembics destined for the concentration of sulphuric acid. 
18. The mother-water, from which have been precipitated the 
ammonio-muriates of platinum and iridium by pouring sy ge 
oO 
