34 
PROPERTIES OF BENZOLINE, OR SPONGE-LAMP SPIRIT. 
the air comes in contact with them, and hence they burn gradually. The explosive sub¬ 
stances may burn simultaneously all throughout their substance, wherein the oxygen is 
diffused, and hence they burn so rapidly as to cause what we call an explosion. The 
great expansion which takes place at the moment of explosion gives the propulsive 
power to gunpowder and other substances which, in the act of explosion, convert solids 
or liquids into gases. The sudden formation and expansion of these gases do the chief 
mischief which accompanies explosions. Thus, common cotton wool is combustible, and 
if fired will burn all over its surface, and gradually through, with a degree of rapidity 
dependent upon the supply of air. Gun-cotton, on the other hand, is the cotton fibre 
somewhat altered, and united with a supply of oxygen in the form of a solid compound 
from which the oxygen is liberated as a gas when it is heated. Thus, every fibre is 
associated with its own supply of oxygen, and the result is the rapid combustion, inde¬ 
pendent of the atmosphere, which we call explosion. Now, the spirit of which we are 
treating is not explosive, as many suppose. It is no more capable of burning below its 
surface than water is. It can only burn as spirits of wine, spirits of turpentine, etc., do,— 
that is, upon the surface, and only there when supplied with air; and it can only con¬ 
tinue burning on the surface so long as the supply of fresh air is continued. The notion 
that such spirit, if fired, will go off like a train of gunpowder is therefore quite fallacious. 
If an iron cylinder, with only one opening, were filled with this spirit, and the spirit 
were fired, it could only burn at the opening, and the size of the flame would be propor¬ 
tionate to the size of the opening. The spirit could not burn within the vessel, and if 
by any means the opening could be stopped, the combustion would immediately cease. 
These simple principles enable us at once to understand how it is that water thrown 
upon such a liquid when burning will, in most cases, increase the conflagration. Being 
of an oily nature, the spirit does not mix with water as spirits of wine would ; and, 
being much lighter than water, it floats upon the water. Thus, if any vessel were filled 
with the burning spirit, and we poured water upon it, the water would sink to the 
bottom, and the spirit would overflow, and, in overflowing, expose a larger surface to 
the air, and thus get more oxygen, and burn more rapidly. When, therefore, such a 
liquid is on fire, our efforts should be directed to confining and smothering it, and the 
use of water avoided. So far we have only considered the liquid, but now we come to 
the vapour of the spirit. This is given off very freely, and it is in fact this which burns 
at the surface of the liquid in the case already considered. Now this vapour, though 
not explosive itself, may readily mix with air, and the mixture constitute an explosive 
compound of a very dangerous character. Let us suppose the case of a steam-boiler 
with only one opening, say the man-hole, filled with the spirit. If a light were applied, 
there would be a blaze, but no explosion, and the flame would be limited by the size of 
the man-hole. Now, let us suppose the same boiler with only a small quantity of 
liquid spirit on the bottom, and this left for a while at a summer-heat temperature ; 
vapour would be given off from the spirit, and the space inside the boiler would in due 
time become a mixture of this vapour and air. Here we should have the oxygen per¬ 
vading the substance of the combustible, as in the gun-cotton, etc., and accordingly the 
mixture would be truly explosive ; and if a light were now applied, we should have a 
dangerous explosion inside the boiler, instead of merely a flame at the man-hole. If an 
ordinary oil-can were full of spirit, and a light applied to the mouth, merely a 
flame would result, which might be extinguished at once by coolly and firmly inserting 
the cork. With a knowledge of these properties, any man or woman with ordinary 
courage would be able at once to extinguish such a can of spirit. A cloth would do it 
easily. Without this knowledge, and under the delusion that the liquid is explosive, the 
can would probably be dropped, the spirit would flow from it, and, spreading out in contact 
with a greater and greater surface of air, the conflagration would be frightful. If, again, 
a can were partly filled with spirit, and by any carelessness a light brought near to it, 
so as to explode the mixture of air and vapour above the spirit, it is of the utmost im¬ 
portance to remember that this instantaneous explosion is all the explosion that can 
occur; that in ninety-nine cases out of a hundred such an explosion would not burst an 
•ordinary tin can ; and that, all the mischief being over at the moment of the explosion, 
the safest thing the holder of the can can do with it is to “ stick to it.” Never in any 
case drop it. Whatever the explosion may do, it has done all its worst when you have 
seen and heard it. The greatest danger is that of spilling the spirit , and this is doubtless 
the cause of all the mischief we hear of. In order to have a clear idea of the real nature 
