90 Mr Murray’s Experiments on the Ignition of Wires. 
Steel- rwire was doubled for one-half its extent ; the single and 
denuded part was alone ignited. 
Platinum-wire was doubled for one-half its extent ; and that 
part only which was single could be ignited. 
Steel- wire was partly enveloped in gold- wire ; only that por- 
tion of the steel-wire which was void of the gold-wire could be 
ignited ; the part encased in the folds of the gold-wire was par- 
tially blued, and was rendered magnetic. 
Copper-wire was twisted round platinum-wire, for half the 
length of the latter. The uncovered platinum was alone igni- 
ted. 
Copper-wire was twisted around steel- wire in the manner of 
the preceding ; the naked steel-wire was ignited alone. 
Steel-wire was twisted round platinum-wire, for one-half its 
length; only that portion of the platinum- wire excepted from 
the steel could be ignited. 
Peculiar phenomena are connected with these exhibitions. 
When the second wire is carried through the whole extent of the 
uniting wire , ignition is . superinduced throughout ; but when 
only partial , the ignition is confined to the denuded portion. 
Copper, platinum, and copper wires, were linked together, and 
made the communicating chain. The platinum placed between 
the copper-wires was ignited alone. 
Platinum, copper , and platinum wires, exhibited, on the tract 
of either platinum-wire, ignition, while the intermediate copper- 
wire remained dark and unignited. 
In the case of steel, copper , and steel wires (so linked toge- 
ther), the steel-wire on each side was ignited, while the copper- 
wire remained unaltered. 
In the chain of platinum, steel and platinum wires, the plati- 
num-wires were exclusively ignited, and the steel unignited. 
In that of steel, platinum and steel, the intermediate link of 
platinum was ignited, and the steel- wire on each end remained 
without ignition. 
In a chain of gold , steel and gold, the gold-wires on each end 
were ignited and fused, and the intermediate steel was not ig- 
nited. 
In one formed of steel, gold and steel wires, the central one of 
gold was exclusively ignited. 
