PRESENT STATE OE THE CHEMISTRY OP GAS-LIGHTING. 
331 
produces no solid particles in the act of burning, it will give me a flame of no appreciable 
luminosity; but I can at once give light to the flame by sifting solid matter, as mag¬ 
nesia or lime, into it; or by dosing it with benzole, or any other volatile hydrocarbon 
which is rich in carbon. Again, I have here the oxyhydrogen flame ; it is barely per¬ 
ceptible until. I direct it on a piece of lime, and then the solid particles of the lime become 
intensely ignited, and a vivid light is the result. 
On the other hand, if I destroy the solid particles of a bright flame, its luminosity dis¬ 
appears. Let me blow air into gas, as I can easily do with this double jet, and you will 
perceive how completely the light is destroyed; but the temperature of the flame is 
considerably increased, for I can now easily melt and burn iron with it. 
The difference, therefore, which we perceive in the light evolved by different flames is 
entirely dependent on the different proportions of solid particles contained in them. 
This spirit of wane and this sulphur burn with little or no light; but this phosphorus, 
and this magnesium burn with a vivid light; and the results in the latter case are due 
to the production of solid particles (phosphoric acid and magnesia), which are intensely 
heated. So again, the electric light is a stream of heated particles of carbon flowing 
from pole to pole. I have not time to enter on the question of the relative luminosity 
of these.several flames, but you will perceive they are all very great; and the considera¬ 
tion which flows from it is, that when we wish to obtain the maximum amount of light 
from any quality of gas, the object should be to detain the particles of carbon in an ignited 
state as long as possible. This can only be accomplished by a proper adaptation of the 
supply of air; for if the supply be too great, the particles of carbon are too quickly 
burnt, and. if it be too little, they escape unconsumed as smoke, and the temperature of 
the flame is reduced. You will see, therefore, that there is no one burner which is suited 
for every quality of gas, unless, indeed, the supply of it to the burner is regulated. I 
have here a number of contrivances which have been invented for the purpose of in¬ 
creasing the illuminating power of a poor gas; but they are all contrivances for checking 
the supply of air to the flame, or for diminishing the too rapid outflow of the gas. I 
regret w r e cannot enter further upon this subject, and that I can only show" you by this 
diagram how much the form and measurement of the burner affect the quality of the 
light:— 
Illuminating Power of Common London Gas ( 13-candle)%when burned from different 
Burners. 
Old brass burner, 15 holes 
Diameter 
of internal 
aperture. 
. . 0-70 in. 
Illuminating 
power 
(sperm 120). 
11-30 
Percentage 
difference. 
100 
do. do. ... 
. . 0-57 
12-12 
108 
Steatite do. . . . 
. . 0-48 
13-23 
117 
do. and gauze .... 
. . ,, 
13-04 
115 
do. 15 holes. 
. . 0-44 
13-56 
120 
do. and gauze .... 
• • 55 
13-35 
118 
do. 15 holes. 
. . 0-43 
13-00 
115 
do. and gauze .... 
• • 55 
13-56 
120 
do. 15 holes. 
. . 0-42 
12-50 
110 
do. and gauze .... 
• • 55 
13-09 
116 
Porcelain (Bengel), 30 holes . 
. . 0-35 
15-33 
135 
All the 15-hole burners had a 7-inch chimney, and the gas w r as burnt at the parlia¬ 
mentary rate of 5 cubic feet per hour; but the 80-hole burner (Bengel) had an 8-inch 
chimney, and the gas was burnt at the rate of a little less than 4 feet per hour, and the 
illuminating power was then calculated to 5 feet. It is evident, therefore, that if a fixed 
quantity of gas—say, 5 feet per hour—is to be passed through the burner, the burner 
must be selected to give the maximum amount of light, and therefore no fixed measure¬ 
ment of burner can be specified ; but if, on the other hand, the burner is a fixed instru¬ 
ment, then the quantity of gas passing it in a given time must be left open, and the 
supply must be regulated to the best effect. This, I believe, is the proper and the fairest 
means of estimating the illuminating power of gas. It would then be said that with a 
certain specified burner—as, for example, the Bengel—a certain amount of light was 
given with not more than a certain quantity of gas. This is the method employed in 
France. In Erdmann’s gas-prover, however, the condition of things is reversed, as w r e 
z 2 
