1881.] An Estimate of Auguste Comte . 401 
of certain of the sciences, that we may see what services he 
has really rendered. 
In physics Comte rejects the so-called imponderables. 
He does not admit, nor does he deny, the existence of the 
so-called ether whose undulations affeCt our senses as light. 
Some credit may belong to him for taking this stand, when 
it is remembered that at the time when the “ Philosophic 
Positive ” was written (1830 — 1842) many French thinkers 
still clung to the conception of “ caloric ” as a substantive 
entity. 
Comte’s classification of the respective branches of physics 
— based professedly, as usual, on “ the degree of generality 
of the corresponding phenomena, on the extent of their 
complication, their relative states of speculative perfection, 
and also their mutual dependence ” — is not happy. His 
order is barology, thermology, acoustics, optics, and electri- 
city. It must surely be admitted that the phenomena of 
light and electricity — the former of which agencies travels 
through the interstellar spaces, whilst the latter probably 
pervades all matter — are far more general than those of 
sound. The classification of the sciences in a linear series, 
on any principles, will be found practicable only by dint of 
arbitrary assumptions and by the negleCt of obvious consi- 
derations. 
Electricity Comte considers as forming a natural transition 
to chemistry. Yet the relations of chemistry and heat are 
now found no less intimate. Indeed he seems to have little 
foreseen how physics and chemistry would approximate and 
almost coalesce in the half-century succeeding the date of 
his first volume. It is no longer safe to say “ Physics treats 
of masses aCting at sensible distances ; chemistry treats of 
molecules aCting at insensible distances.” In physics we 
meet with abundant cases of molecular aCtion. Nor are 
specific differences wanting in the physical properties of 
bodies. We may take three crystals, one of which, in virtue 
of its molecular structure, shall cause the plane of polarisa- 
tion to rotate to the right, the second to the left, whilst the 
third leaves it unaffected ! 
Comte maintains that dualism requires to be universally 
received in chemistry Philosophic Pos.,” iii. 103 — 9), even 
as regards organic compounds. Here, then, we have a want 
of insight into the future prospects of a science scarcely less 
striking than he displays in biology by his denial of the mu- 
tability of organic species. It is perfectly true that in 1838 
dualism was still in the ascendant, but indications were not 
wanting which might have been sufficient for a man of such 
