1878.] 
On Residual Phenomena . 
25 
Perceiving that the atomic weight of hydrogen was lower 
than that of any other element, he put forward the law that 
bears his name, — i.e., that if we take the atomic weight of 
hydrogen = 1, the atomic weights of all the other elements 
will be multiples of 1 by some whole number. The sug- 
gestion agreed tolerably well with the state of chemical 
knowledge in his day. Not a few atomic weights, calculated 
on the hydrogen standard, had been found to be whole num- 
bers, and there was at least room to anticipate that, on 
further and more accurate research, the fractions with which 
the atomic numbers of the remainder were encumbered 
might prove to be the result of error. There was, moreover, 
about the proposed law an appearance of “ simplicity ” which 
could not fail to recommend it to general notice. Let us 
hasten to declare that we put little faith in such simplicity. 
It is a conception totally ex parte hominis. Wheresoever we 
have attempted to interrogate Nature somewhat closely, we 
have utterly failed to perceive that simplicity, as it appears 
to man, is any part of her plan. When, therefore, a law or 
a theory is recommended on the ground of its simplicity our 
suspicions are aroused, and we fear lest the fadts have been 
garbled and manipulated. 
On the other hand, a certain amount of confirmation is 
lent to Dr. Prout’s view by the observations of astro- 
spedtroscopists, that hydrogen predominates in the stars 
whose temperature seems highest, and where the dissociation- 
process must be most adlive. Hence it is contended hydro- 
gen may be a more primitive stage of development of the 
primordial element, or elements, than any other substance 
with which we are acquainted. Still, admitting such to be the 
nature of hydrogen, the truth of Prout’s law is by no means 
a necessary consequence. The more accurate determination 
of the atomic weights of the elements, again, has by no 
means, as was anticipated, tended to free them from frac- 
tions. Hence the value generally attached to Prout’s law 
has not latterly been increasing. Dumas, who is one of its 
most distinguished upholders, proposes the modification that 
all atomic weights are multiples by a whole number, if not 
of 1, yet of o’25 or 0*50, maintaining that out of fifty-eight 
atomic weights not more than half-a-dozen differ appreciably 
from multiples by whole numbers of half the atomic weight 
of hydrogen, whilst some of the exceptional elementary 
weights are multiples of one-fourth the atomic weight of 
hydrogen. Here, however, we enter upon dangerous ground. 
If, multiplying ro by a series of whole numbers, we obtain 
products coinciding with the atomic weights of the elements, 
