17 
points ; and it occurred to me to try the effect of covering 
each of the carbons with a thin coating of hydrate of lime, 
and mounting them parallel to each other in separate hol- 
ders, and without any insulating material between them. 
The use of the lime covering was intended to prevent the 
light from travelling down the contiguous sides of the car- 
bons. On completing the electric circuit the light was 
maintained between the two points, and the carbons were 
consumed in the same regular manner as when the insula- 
ting material had been placed between them. 
Two plain cylindrical rods of carbon three sixteenths of 
an inch in diameter, and eight inches long, were now fixed 
in the holders parallel to each other, and one eighth of an 
inch apart. The strength of the alternating current was 
such that it would fuse an iron wire 0 025 of an inch 
in diameter and eight feet in length. On establishing the 
electric current through the points of the carbons by means 
of a conducting paste composed of carbon and gum, the 
light was produced, and the carbons burnt steadily down- 
wards as before. 
Four pairs of naked carbons mounted in this manner 
were next placed in series in the circuit of a four-light 
machine, and the light was produced from these carbons 
simultaneously, as when the insulating material was used 
between them. The light from the naked carbons was also 
more regular than that from the insulated ones, as the plaster 
of Paris insulation did not always consume at the same 
rate as the carbons, and thereby obstructed the passage of 
the current. This was evident from the rosy tinge of the 
light produced by the volatilisation of the calcium simul- 
taneously with the diminution of the brilliancy of the light 
from the carbons. 
The only function, therefore, which the insulating mate- 
rial performs in the electric candle, as shown by these 
experiments, is that it conceals the singular and beautiful 
