144 MALUS. 
mathematicians and physicists of the Emission School in 
Europe, to afford a mathematical proof of the truth of 
the emission theory. It is assuredly a singular thing that 
there should be this perfect identity of refractive powers 
calculated from angles of disappearance differing from 
each other, and according to formulas very dissimilar be- 
tween themselves. 
But what proof was there that the refractive powers 
ought to be identical? Ought we to suppose that the 
change from the solid to the fluid state in any substance 
would be without influence on its refractive power? 
Might we not cite cases in which heat modifies the re- 
fractive power of bodies independently of their density ? 
Again, were the temperature of the wax and its density 
well ascertained at the moment of the experiment such 
as Malus was obliged to make it? Besides, would it be 
strange to suppose that within those limits where the 
action of bodies on light operates, there are no sub- 
stances truly opaque! 
Now that the system of emission is overthrown without 
hope of restoration, I endeavour to recall all the circum- 
stances by which Malus might possibly have been misled. 
But, for my own part, I feel sure that I do not deceive 
myself in affirming that the memoir of which we are 
speaking offers a new proof of the mathematical spirit 
and experimental talent which Malus possessed in so 
high a degree. We ought only to regret that the 
conclusions in the report were, so explicit that they . 
represented the atomic theory of light as completely 
established ; and that such a decision, emanating from 
individuals so competent as Laplace, Haiiy, and Gay- 
Lussac, may perhaps have contributed to alienate our 
illustrious associate from that experimental path which 
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