I8S5.J 
Analyses of Books. 
91 
a guide in quest of faifts. It is especially necessary to do this, 
I think, in dealing with the questions concerning structural 
formulae. If these formulae are dissociated from the chemical 
fadts which they symbolise, they become intellectual tyrants; if 
each formula is considered simply as a summary of facts re- 
garding the compound formulated, they are to be classed with 
the other ‘ brute beasts of the intellectual domain,’ and cease to 
have much interest for one who believes that chemistry is a 
branch of science.” 
These passages may suggest serious reflections not a few. 
At present we will merely hint that the modern love for struc- 
tural formulae may be due to the contemporary examination- 
mania. The power of remembering “ spread-eagles,” reproducing 
them on the black-board, and expounding their supposed meaning 
is easily tested by the examiner, — one great duty of the “ coach” 
being to ascertain what particular breed of spread-eagles any 
given examiner recognises in the only legitimate and heil- 
bringende. 
A prominent attribute of Mr. Muir, as it was of Kolbe, is his 
dislike of vagueness and looseness of thought and expression. 
Thus we find him writing: — “ Much is to be expecfted from re- 
searches into the phenomena which occupy the border-land 
between chemistry and physics. If the knowledge chemists 
already have of the structure of molecules, meagre though that 
knowledge be, can be supplemented by definite dynamical con- 
ceptions, obtainable in part by the methods of thermal chemistry, 
then we may hope that chemistry will enter on a new stage of 
advance as a branch of the science of matter and motion. It 
seems to me that a most important step will be made if the bond- 
theory of valency is generally abandoned ; with it will go all 
those quasi-dynamieal expressions, the offspring of loose and 
slipshod ways of thinking, which have gathered round that 
strange anomaly a ‘ unit of affinity ’ employed as a variable 
standard for measuring nothing.” 
Further, in passing judgment upon Berthelot’s thermo-chemical 
researches, our author says : — “ Berthelot’s work is saturated with 
the conceptions of the molecular ; but by some fatal perverseness 
he refuses to apply this theory to chemical phenomena. While 
recognising the existence of molecules, and building his general- 
isation on a molecular foundation, he refuses to accept the con- 
ception of atom, or rather he hopelessly confuses it with that of 
equivalent. The molecule is for him a definite and definable 
portion of matter; the parts of the molecule are only numbers.” 
The periodic law is very fully and clearly discussed. It may, 
however, be doubted whether the merit of Mr. Newlands, in 
the initiation of this important generalisation, is brought into 
sufficient prominence. “ Meyer’s curve and its explanation are 
given. Carnelley’s suggestion, that the fusibility of the ele- 
ments varies periodically with their atomic weights, is discussed, 
