Ill 
1878 .] Notices of Books. 
momentum ; of force, and the composition and resolution of 
forces ; of the properties of matter ; of gravitation ; of the equi- 
librium of simple mechanical arrangements ; of falling bodies ; 
of curvilinear motion ; of work and energy. The author, laud- 
ably enough, advises his readers to make themselves familiar with 
the metric system of weights and measures, but we fear that he 
is too sanguine in holding that these must shortly become uni- 
versally employed. 
In the “ Exercises ” at the end of the book we find the very 
remarkable statement that “ a gallon of water weighs 18 lbs.” 
This is doubtless a typographical error, but it calls for prompt 
correction* The work is well arranged, and the explanations 
lucid. 
A Treatise on Chemistry. By H. E. Roscoe, F.R.S., and C. 
Schorlemmer, F.R.S., Professors in the Owens College, 
Manchester. Vol. I. The Non-metallic Elements. London : 
Macmillan and Co. 1877. 
It is now some years since a treatise on chemistry of any mag- 
nitude has been published in this country, and all students of 
chemistry will welcome the volume of Profs. Roscoe and Schor- 
lemmer as a real addition to their science. Embracing the newest 
discoveries and the newest methods, it aims to give a clear and 
detail account of Modern Chemistry, taken in its broadest signi- 
ficance. When we call to mind the large experience and untiring 
industry of the authors, both as regards original research and 
professorial teaching in ledture-room and laboratory, we have a 
right to expedt a very able treatment of the subjedf at their hands. 
This expectation is fully realised. 
Out of the 750 pages of which this first volume consists, 40 are 
given to an historical introduction, 54 to the general principles of 
the science, 610 to the non-metallic elements, and 46 to crystal- 
lography. The Introduction gives a brief but very lucid account 
of the rise and progress of the science, traced from the earliest 
times to discoveries of Priestley, Scheele, and Lavoisier, and 
the development of the atomic theory by Dr. Alton. The more 
prominent faCts in the history of organic chemistry are also 
detailed. In the second seCtion the laws of chemical combination 
are clearly explained, and the manner in which the combining 
weights of bodies are obtained from the analysis of compounds. 
The kinetic theory of gases and diffusion and effusion are dis- 
cussed, and a brief but all-sufficient account of chemical nomen- 
clature concludes this sedtion. 
The non-metals are divided into the four usual groups, according 
to their atomicities, and they are described in the order in which 
they there occur. The account of ozone contains all that we 
