Metals &;c. in Fused Substances. 451 



A mixture of black scale Oxide of Iron and Silica. — Iron, car^ 

 bon, platinum. Reversal with iron and carbon. Current strong 

 with iron and platinum. Iron dissolved. 



Protoxide of Copper. — Platinum positive to iron as long as 

 iron was enveloped by an unfused coating of oxide of copper, 

 then violent action upon the iron attended by evolution of in- 

 tense heat and very rapid solution of the iron, the iron at the 

 same time becoming strongly positive to platinum. A large 

 button of reduced copper was formed. Protoxide of copper 

 appears to evolve oxygen gas when fused. 



The following inferences may be deduced from these experi- 

 ments. The most negative substances in fused salts are generally 

 platinum, gold, carbon, and silver; the most positive substances 

 are generally magnesium, aluminium, and zinc. Silicium is 

 generally electro-positive to carbon ; and is strongly positive and 

 quickly corroded in fused alkalies, alkaline carbonates, or fluo- 

 rides. Carbon is not generally very positive to iron. 



The following facts may also be noticed. Copper and silver 

 dissolve rapidly in fused sulphide of potassium, tersulphide of 

 antimony, or iodide of lead; silver also dissolves freely in iodide 

 of barium, or bisulphide of arsenic. Platinum, copper, and silver 

 rapidly melt in fused arsenite of soda. Electric currents were 

 repeatedly observed whilst one (or both) of the electrodes was 

 coated with unfused salt, and on the fusion of the saline coating 

 strong currents in an opposite direction generally occurred. 



The investigation was very suggestive of new experiments ; it 

 suggested the examination of the various phenomena which acted 

 as sources of interference, which I have already enumerated; it 

 also threw light upon the desirable object of obtaining a cheap 

 source of electricity by the combustion of coke or gas- carbon. 

 The discovery of some suitable fused salt or mixture in which 

 carbon is highly electro-positive at a high temperature to iron, 

 nickel, or other infusible and suitable conductor, would probably 

 prove a cheap and powerful source of electricity ; cheap because 

 of the low equivalent number of carbon and the low price of 

 coke and gas-graphite, and powerful because of the intense affi- 

 nity of carbon for oxygen at high temperatures, sufficient indeed 

 to set the alkali- metals free from their oxides. The nearest 

 approach to this object in these experiments was with carbon and 

 nickel in a fused mixture of soda, lime, and silica. 



2G2 



