126 DESCRIPTIONS OF MIXERALS. 



18-94. In the year 1822, a mass from Condoto was de- 

 posited in the Madrid Museum, measuring 2 inches and 4 

 lines in diameter, and weighing 11,641 grains. A more 

 remarkable specimen was found in the year 1827 in the 

 Urals, not far from the Demidoff mines, which weighed 1U- 

 (more accurately, 11*57) pounds troy; and similar masses 

 are now not uncommon. The largest yet discovered weighed 

 21 pounds troy ; it is in the Demidoff cabinet. 



Russia affords annually about 35 cwt. of platinum, which 

 is about five times the amount from Brazil, Borneo, Colom- 

 bia, and St. Domingo. Borneo affords about 500 pounds 

 per year. 



The North Carolina platinum was found with gold in 

 Rutherford County. It was a single reniform granule, weigh- 

 ing 2*54 grains. Other instances are reported from the 

 Sou hern gold region. 



The infusibility of platinum and its resistance to the 

 action of the air, and moisture, and most chemical agents, 

 renders it of great value for the construction of chemical 

 and philosophical apparatus. The large stills employed in 

 the concentration of sulphuric acid are now made of plati- 

 num ; but such stills are gilt within, since platinum when 

 unprotected is acted upon by the acid, and soon becomes 

 porous. It is also used for crucibles and capsules in chemi- 

 cal analysis ; for galvanic batteries ; as foil, or worked into 

 cups or forceps, for supporting objects before the blowpipe. 

 It alloys readily when heated with iron, lead, and several of 

 the metals, and is also attacked by caustic potash and phos- 

 phoric acid, in contact with carbon ; and consequently there 

 should be caution when heating it not to expose it to these 

 agents. 



It is employed for coating copper and brass ; also for 

 painting porcelain and giving it a steel lustre, formerly 

 highly prized. It admits of being drawn into wire of ex- 

 treme tenuitv. 



Platinum was formally coined in Russia. The coins had 

 the value of 11 and 22 rubles each. 



This metal fuses readily before the " compound blow- 

 pipe ;' ? and Dr. Hare succeeded in 1837 in melting twenty- 

 eight ounces into one mass. The metal was almost as malle- 

 able and as good for working as that obtained by the other 

 process; it had a specific gravity of 19-8. He' afterwards 

 succeeded in obtaining from the ore masses which were 90 



