196 ANNUAL OF SCIENTIFIC DISCOVERY. 



more plentiful. It may then, perhaps, be applied to other useful purposes 

 in which its weight and slightly tarnished color will be no objection, or for 

 which its absolute unahcrability will give it a peculiar value. The solution 

 of these questions, however, depends on the price for which the metal can 

 be supplied; and the chemist is particularly interested in seeing its cost so 

 far reduced that the large vessels of the laboratory may be made of plati- 

 num. It was in the hope of facilitating a progress of this kind, that MM. 

 Deville and Debray, of France, undertook a series of difficult researches, 

 costing four years of labor, the results of which have been recently given to 

 the public in the Annahs de Chimie e.t Physique. 



Until the first communications of these chemists were published, no one 

 dreamed of utilizing all the metals found with platinum, and with the excep- 

 tion of palladium and osmium, which there was always a motive for sepa- 

 rating, platinum alone has been extracted from the ores, leaving a residue, 

 which has accumulated in all the manufactories in Europe as well as in the 

 Russian Mint. 



The processes described by them are exclusively by the dry way, and by 

 fusion at a very high temperature. They are given in different chapters, 

 which treat of " the revivification of pure platinum/' "the metallurgy of pure 

 platinum," " the extraction from the rough ore of a triple alloy of platinum, 

 rhodium, and indium of a suitable and invariable composition; " and, lastly, 

 the extraction, whether from the residues or from the osmide of indium, of 

 the utilizable metals, platinum, palladium, rhodium, and iridium. 



The apparatus by means of which these French chemists have succeeded 

 in melting platinum in considerable quantities and casting it into ingots, 

 consists of a furnace of lime bound with iron wire. The fuel most often 

 employed was common coal-gas, but hydrogen may be used, and when pure 

 will give a greater heat. The combustion was fed with a current of oxygen. 



In commerce, platinum is found which is almost free from iridium, but 

 which still contains traces of osmium and a little silicium. MM. Deville and 

 Debray have discovered that fusion in lime by means of an oxidizing flame 

 refines it perfectly, osmic acid being disengaged, and the silicium becoming 

 converted into silicate of lime, which melts into a colorless bead, and moves 

 rapidly about on the surface of the metal until it reaches the edge, where it 

 is absorbed by the sides of the furnace. Platinum so melted and refined is 

 a metal as soft as copper; it is whiter than ordinary platinum,, and does not 

 possess the porosity which has hitherto been an obstacle to the manufacture 

 of an impermeable platinum sheath. 



Melted platinum still possesses the property of condensing gases at its 

 surface, and of producing the phenomenon of a lamp without flame. Its 

 density = 21 .15, less than the density of ordinary platinum which has been 

 subjected in the working to a powerful hammering. 



At a meeting of the French Academy, June 4th, 18iiO, MM. Deville and 

 Debray exhibited (1.) Two ingots of platinum weighing together twenty- 

 five kilogrammes, fused in the same fire and cast in an ingot mould of cast 

 iron. The surface of the metal shows evidence of perfect fluidity and 

 carries the impression of characters engraved on the surface of the mould. 



(-'.) A toothed wheel of platinum, cast in ordinary founders' sand, was also 

 shown. This was cast in the mode common for cast iron, in a two-part flask, 

 wirh a sprue and vent holes as usual. 



The metal u:-[ was obtained from a quantity of crude platinum and 

 puuiiuini money placed at iheir disposal by the Russian Government. 



