VOL. XLVIII.] PHILOSOPHICAL TRANSACTIONS. SOQ 



by a moderate blow, of a close texture, uneven surface, and rough jagged edges; 

 tlie colour was very dark, with a faint purplish cast. 



2. One part of platina and 2 of lead, covered with borax and black flux, and 

 exposed to a gradual fire, in a wind furnace, did not come into fusion till the fire 

 had been raised to a strong white heat : from the continuance of heat in this ex- 

 periment the loss was great, being nearly -^ of the mixture. The ingot proved 

 hard and brittle, like the preceding, but broke with a striated surface. 



3. One ounce of platina and 3 of lead, treated in the same manner, required 

 still a very strong fire for their perfect fusion: and lost about Vt* The metal 

 broke less easily than either of the preceding, and in some measure yielded to the 

 hammer: the colour was somewhat darker, and inclined more to purplish. 



4. One part of platina and 4 of lead, being covered with black flux and com- 

 mon salt, and committed to a wind furnace, the platina was not perfectly taken 

 up, till the fire had been raised to a considerably strong white heat; the loss was 

 -,1^. The same proportions of the metals, injected into a fluid mixture of the 

 flux and salt, previously brought to the above degree of heat, almost instantly 

 melted, and lost only -tb-o- The ingot was much tougher than the foregoing, 

 filed well, and cut tolerably smooth with a knife. On breaking, the upper part 

 appeared composed of bright plates, the lower of dark purplish grains. 



5. One part of platina and 8 of lead united easily in a quick fire, and lost little 

 or nothing. The metal worked and looked like very bad lead; on breaking, 

 the texture appeared partly composed of transverse fibres, and partly of grains; 

 the colour dull and purplish. 



6. One part of platina and 12 of lead united, without loss, into a compound 

 very little difl^erent from the foregoing. On breaking, its texture was somewhat 

 finer, and composed chiefly of fibres, with very few grains. 



7. A mixture of 1 part of platina and 24 of lead proved not very much harder 

 than lead of a middling quality. The colour was still somewhat purplish, and 

 the texture fibrous ; but the fibres were remarkably finer than where the platina 

 was in larger proportion. 



8. The foregoing compositions, when newly polished, appeared in general of 

 a dark iron colour; which, on exposure to the air, quickly tarnished to a brownish 

 yellow, a deep purplish, and at length a blackish. They all filed freely, without 

 sticking in the teeth of the file, as lead does by itself. 



9. On returning these compounds to the fire a second time, it was constantly 

 observed, that after they had come into perfect fusion, if the heat was slackened 

 a little, great part of the platina subsided; that ne\ertheless, the lead decanted 

 off^, even in a heat below ignition, retained so much of the platina, as rendered 

 it of a fine fibrous texture, and purplish colour. 



The several mixtures, covered with black flux, and kept in strong fusion, in 



