Count Rumford's Account of a Method of 
io 4 
Olive oil. Burnt in an Argand’s lamp, 
The same burnt in a common lamp, 
with a clear, bright flame, without 
smoke, - 
Rape oil. Burnt in the same manner, 
Linseed oil. Likewise burnt in the same manner, 
1 should have been very glad to have made the experiment 
with whale oil, but there was none to be had in the country I 
inhabit. 
With the foregoing table, and the prices current of the 
therein mentioned articles, the relative prices of light pro- 
duced by those different materials may very readily be com- 
puted. 
The light of a wax candle, for instance, costs just nine times 
more at Munich, than the same quantity of light produced by 
burning rape oil in an Argand s lamp. 
Of the Transparency of Flame . 
To ascertain the transparency of flame, or the measure of the 
resistance it opposes to the passage of foreign or extraneous 
light through it, I placed before the photometer, over against 
the standard lamp, two burning wax candles, well trimmed ; 
and putting them near together, sometimes by the sides of 
each other, and sometimes in a straight line behind each other, 
I found that when their distances from the field of the photo- 
meter were the same, the intensity of the illumination was to 
all appearance the same, whether the light of the one was 
made to pass through the flame of the other, or not. And 
Equal parts 
in weight. 
110 
129 
125 
120 
