Chemistry. 387 
spotted with very minute and sparkling crystalline points. This 
alloy was less silvery and brilliant than that with silica and char- 
coal. 
Glucina^ Platinum and Antimony.^ — had a colour not unlike 
a specimen of native nickel from Hesse in my possession, or 
intermediate between pure nickel and refined silver. Scarcely 
abraded by the knife. Crushed in the steel-mortar, it was 
less granular and angular in its particles than the preceding. 
Alumina.^ Antimony and Platinum^ very much resembled the 
former, but was a shade darker in colour. 
The alloy with silica, charcoal, potassium^ antimony and pla- 
tinum; and that with zirconia, potassium^ &c. seemed to differ 
little from those without potassium. The potassium burns be- 
fore the fusion of the alloy takes place, and perforating the pla- 
tinum-foil, escapes in the character of flame, so that it would; 
only preserve the reduction of the earthy oxide. 
The combination of Zmc, Platinum^ and Protoxide of Ba^ 
rium was ragged, scoriaceous, and very hard. 
16.- Apparent conversion of Cast-Iron into Plumbago. — In 
the last number of the American Journal of Science, Professor 
Silliman has given an account of a six-pound shot found at 
Newhaven Harbour, and supposed to have been there ever since 
1779, which was encrusted with a shapeless, rusty brownish 
substance, unctuous, sectile, and leaving a mark on paper like 
plumbago.. Various facts of the same kind have been observed 
in this country ; and very recently Mr Hatchett obtained from 
Mr Whidbey at Plymouth a portion of a cast-iron gun which 
had been long immersed in sea-water. Mr Brande found it to 
consist of Oxide of Iron 81, and Plumbago 16 ; and he attrh 
butes the rapid decay and change in the cast-iron to a galvanic 
action, the plumbaginous crust in contact with the cast-metal 
producing an electro-motive combination, aided by and promot- 
ing the decomposition of the sea-.water, and of its saline con- 
tents.” — -See Quarterly Journal^ vol. xii. p. 407. The late Mr 
James Watt long ago remarked this change in cast-iron, in the 
pumps of his steam-engines that had been exposed to the action 
of salt-water. 
