332 Lieut. Drummond on the means of facilitating the 
Of these substances, and also of their compounds with one 
another, lime appearing to possess a decided superiority, my 
subsequent experiments were confined to it alone, and by a 
more perfect adjustment of the apparatus, by bringing the 
maximum heat, which is confined within narrow limits, 
exactly to the surface of the ball, and by using smaller balls 
than those employed in the early experiments, a very material 
increase of light has been obtained. The mean of 10 expe- 
riments, made lately with every precaution, gives for the 
light emitted by lime, when exposed to this intense heat, 83 
times the intensity of the brightest part of the flame of an 
argand burner of the best construction, and supplied with the 
finest oil. The lime from chalk, and such as is known at 
the London wharfs by the name of flame lime, appears to be 
more brilliant than any that has been tried. 
When well burned Carrara marble is made into a paste 
with water, and gradually dried, it appears to be nearly equal 
to the preceding: when strongly compressed, or very porous, 
in both cases it is inferior. 
The lime from the chalk, besides being the most brilliant, 
is in other respects very convenient for use ; it admits of 
being turned in the lathe, and thus any number of the small 
focal balls, with slender stems attached to them, may be 
prepared with the utmost facility, uniform in size, and perfect 
in figure. The surface of the ball, by the continued action 
of the heat, appears to be kept nearly in a state of fusion ; it 
is gradually worn down ; and, on cooling, presents a semi- 
crystalline appearance. Being desirous of ascertaining what 
effect so intense a light would have on a mixture of chlorine 
and hydrogen, two tubes 10 inches long, with bulbs about 
