66 Royal Societj/. 



superior lightness, and the effect of fluxes being accomplished by the 

 solvent powers of water. 



The gray precipitate of platina being thus obtained in the form of 

 a uniform mud or pulp, is now ready for casting, which is effected by 

 compression in a mould, formed of a brass barrel, six inches and a half 

 long, and turned rather taper within, so as to facilitate the extraction 

 of the ingot when formed. The platina is first subjected to partial 

 compression by the hand with a wooden plug, so as to expel the 

 greater part of the water. It is then placed horizontally in an iron 

 press, constructed so as to give great mechanical advantage to the 

 power applied to produce compression. The cake of platina is then 

 to be heated to redness by a charcoal fire, in order to drive off all the 

 remaining moisture j afterwards subjected to the most intense heat of 

 a wind furnace ; and lastly, struck, with certain precautions, while 

 hot, with a heavy hammer, so as effectually to close the metal. The 

 ingot thus obtained may, like that of any otlier metal, be reduced, by 

 the processes of heating and forging, to any other form that may be 

 required. It may then be flattened into leaf, drawn into wire, or sub- 

 mitted to any of the processes of which the most ductile metals are 

 capable. 



The perfection of the above method of giving complete malleability 

 to platina is proved by comparing the specific gravity of a fine wire 

 of that metal obtained by this process, which is found to be 21'5, with 

 that of a similar wire drawn from a button which had been completely 

 fused by the late Dr. Clarke, with an oxy-hydrogen blowpipe, and 

 which the author ascertained was only 21'1C. A further proof of the 

 excellence of the method employed by the author is derived from the 

 great tenacity of the platina thus obtained, as determined by a com- 

 parison of the weights required to break wires made of this metal so 

 prepared, and similar wire of gold and of Iron. These weights he 

 found to be in the proportion of the numbers 590, 500^ and 600, re- 

 spectively. 



An account is subjoined of the process for obtaining malleable pal- 

 ladium, by the intermedium of sulphur ; and also of that for procuring 

 the oxide of osmium in a pure, white, and crystallized state. 



Dec. I. — At the Anniversary Meeting of the Royal Society, on St. 

 Andrew's day, — after the names had been read of all Members de- 

 ceased in the preceding year, and I)efbre the Medals were delivered, 

 Mr. Davies Gilbert (President) addressed the Society to the follow- 

 ing effect. 



It would be vain to expect that the anniversary meeting of a body 

 so numerous as the Royal Society should ever occur, without exciting 

 in our minds sensations of deej) regret for the loss of many individuals 

 distinguished by their abilities, by their acquirements, by their virtues, 

 and endeared to other members by the ties of ])rivate friendship. We 

 may also add, with feelings of exultation in regard to the honour of 

 the Society, however painfully they may bear upon ourselves, that the 

 number of those among us sharing in our active labours, far exceeds 

 the limit that might justify a hope of our not being called on to de- 

 plore some of these more conspicuous Fellows of. the Society on the 

 present occasion. Although 



