222 Notices respecting New Books. 
The result of the experiments hitherto made renders it 
scarcely doubtful that the pendulum, which does such excel- 
lent service in all problems bearing on the determination of 
gravity, will also give useful results for our present purpose ; 
and in the immediate future I hope, by means of an apparatus 
constructed by Repsold, of Hamburg, to continue these 
observations in the astrophysical observatory ard to bring 
them to a conclusion. 
XXXVI. Notices respecting New Books. 
A Treatise on the Principles of Chemistry. By M. M. Parrison 
Moir, V.A., F.RS.E., Fellow, and Prelector in Chemistry, of Gon- 
ville and Caius College, Cambridge. Cambridge: The University 
Press. 
R. MUIR’S book is certainly one of the most important con- 
tributions which have been made to general English Chemical 
literature for many years, and will, we feel sure, be heartily 
welcomed by all who are engaged in teaching chemical science in 
this country. A text-book of a like scope to Lothar Meyer’s well- 
known Moderne Theorien der Chemie has long been a desidera- 
tum ; and it is surprising that a translation of the latter into the 
English language has not been published long ere this. Such 
a translation will, however, not be in such request now that Mr. 
Muir has brought out a book similar in kind, and, as we think, of 
equal merit, and probably more suitable for Eng’’<h studenis than 
a translation of the German work would have been. 
The volume is not of course an elementary text-book, but is 
intended for advanced students and teachers, giving a lucid and 
comprehensive view of chemical theory and the general princioles of 
the science down to the most recent date. The author says he has 
“tried to deal with chemical facts and generalizations so as to show 
their reality,” and in this we think he has eminently succeeded. 
Mr. Muir possesses the happy method of. marshalling even dry 
facts in a manner both interesting and instructive, and of eliciting 
therefrom the information which they are designed to teach. His 
success in this respect is in great part due to his having throughout 
“‘ followed in the very footprints of the great discoverers, watched 
them as they make their footing sure and as they feel their way 
up the heights.” This is undoubtedly the plan on which a treatise 
on chemical principles and theory should be written. When pre- 
sented in this manner the student is always in a position to see 
where fact ends and hypothesis begins, and is thus enabled to judge 
for himself as to the particular value to be placed on any given 
theory. As an example of this we may mention more especially 
the capital summary of atomic heat-determinations and their 
bearing on the determination of atomic weights. This me hod 
has also an educational value in showing how abstruse che aical 
