THE ELEMENTS. 
211 
III. Of fire, we have said that it dissolves. The only 
idea probably which this term raised in the reader’s mind, 
was that of fire melting metals, resins, and some other 
substances, fluxing ores, running glass, and assisting us in 
ma:.y of our operations, chemical or culinary. Now these 
are only uses of an occasional kind, and give us a very 
imperfect notion of what fire does for us. The grand im¬ 
portance of this dissolving power, the great office indeed of 
fire in the economy of nature, is keeping things in a state 
of solution, that is to say, in a state of fluidity. Were it 
not for the presence of heat, or of a certain degree of it, all 
fluids would be frozen. The ocean itself would be a quar¬ 
ry of ice; universal nature stiff and dead. 
We see, therefore, that the elements bear not only a 
strict relation to the constitution of organized bodies, but 
a relation to each other. W~ater could not perform its of¬ 
fice to the earth without air; nor exist, as water, without fire. 
IV. Of light, (whether we regard it as of the same 
substance with fire, or as a different substance,) it is alto¬ 
gether superfluous to expatiate upon the use. No man dis¬ 
putes it. The observations, therefore, which I shall offer, 
respect that little which we seem to know of its constitution. 
Light travels from the sun at the rate of twelve million 
of miles in a minute. Urged by such a velocity, with 
what force must its particles drive against, (I will not say 
the eye, the tenderest of animal substances, but) every 
substance, animate or inanimate, which stands in its way! 
It might seem to be a force sufficient to shatter to atoms 
© 
the hardest bodies. 
How then is this effect, the consequence of such pro¬ 
digious velocity, guarded against ? By a proportionable 
minuteness of the particles of which light is composed. It is 
impossible for the human mind to imagine to itself any¬ 
thing so small as a particle of light. But this extreme ex¬ 
ility, though difficult to conceive, it is easy to prove. A drop 
of tallow, expended in the wick of a farthing candle, shall 
send forth rays sufficient to fill a hemisphere of a mile di¬ 
ameter; and to fill it so full of these rays, that an aperture 
not larger than the pupil of an eye, wherever it be placed 
within the hemisphere, shall be sure to receive some of 
them. What floods of light are continually poured from 
the sun, we cannot estimate; but the immensity of the 
sphere which is filled with its particles, even if it reached 
no farther than the orbit of the eqjth, we can in some sort 
compute; and we have reason to believe, that throughout 
this whole region, the particles of light lie, in latitude at 
