8 DR. WOLLASTON ON RENDERING PLATINA MALLEABLE. 



patience and perseverance^ before the cake can be brought to bear hard blows: 

 but it may, by these means, at length be made so flat and square, as to bear 

 being passed through the flatting-mill, and so laminated to any required de- 

 gree of thinness. 



Thus prepared, it is always brittle, while hot ; possibly, from its still con- 

 taining a small remnant of sulphur. I have also fused some palladium per se, 

 without using sulphur ; but I have always found it, when treated in this way, 

 so hard and difficult to manage, that I greatly prefer the former process. 



To obtain the oxide of Osmium in a pure, solid, and crystallized state, I grind 

 together, and introduce, when ground, into a cold crucible, 3 parts by weight 

 of the pulverulent ore of iridium, and 1 part of nitre. The crucible is to be 

 heated to a good red in an open fire, until tlie ingredients are reduced to a 

 pasty state ; when osmic fumes will be found to arise from it. The soluble 

 parts of the mixture are then to be dissolved in the smallest quantity of water 

 necessary for the purpose, and the liquor, thus obtained, is to be mixed, in a re- 

 tort, with so much sulphuric acid, diluted with its weight of water, as is equi- 

 valent to the potash contained in the nitre employed ; but no inconvenience 

 will result from using an excess of sulphuric acid. By distilling rapidly into 

 a clean receiver, for so long a time as the osmic fumes continue to come over, 

 the oxide will be collected in the form of a white crust on the sides of the re- 

 ceiver; and there melting, it will run down in drops beneath the watery solution, 

 forming a fluid flattened globule at the bottom. When the receiver has be- 

 come quite cold, the oxide will become solid and crystallize. One such opera- 

 tion has yielded 30 grains of the crystallized oxide, besides a strong aqueous 

 solution of it. 



