CHABANEAU
69
It is to be noted that there were two necessary conditions for the preparation of malleable platinum, either of which was useless without the other. First, the metal must be obtained from the ore in a pure condition, for unless separated not only from the base metals, but also from the largest part of the other platinum metals, the sponge can not be welded into a malleable mass; second, while at a high temperature the sponge of pure platinum is easily compressed into a malleable ingot, at low temperatures it has no coherence. Virtually this process, generally attributed to Knight, was in use almost exclusively until the last third of the nineteenth century.
Chabaneau was for some time engaged in preparing large quantities of malleable platinum. Then his patron, Marquess d'Aranda, having been appointed ambassador to France (1787), he was prevailed on to accompany him to Paris, in order to convert under his auspices some of the new metal into ornaments for the crown. Jeanetty, goldsmith to the court of France and a very able man, had been commissioned for this work, and he sought vainly to discover the process used by Chabaneau. He did, however, discover another method (alloying with arsenic) and employed it with such success that he founded in Paris a manufactory for platinum ware, which prospered down to 1820. At present the method of compression while hot, without alloying, is used, and that of Jeanetty has been abandoned.
It was only two years after this memoir was written that Deville and Debray perfected the method first proposed by Hare in 1838 of fusing platinum in the flame of the oxygen-hydrogen blowpipe. The memoir is somewhat misleading regarding the process of Jeanty (or Jeanetty), for while it is true that he did for many years manufacture platinum crucibles and other vessels by his method, it was early in the century entirely supplanted by the compression method, and it is doubtful if much practical application was ever made of it.