Chemistry and Physics. 255 
it converting the methyl group into carboxyl and nitrating the 
rest, giving a strong dibasic acid. This splits up giving a nitro- 
body C,H,N,O,, which when reduced gives C,H,N,O,, a body 
differing from xanthin by H,O less and which gives the murexide 
reaction.— Ber. Berl. Chem. Ges., xvii, 2846, Jan. 1885. 6. F. B 
8. A Treatise on the Principles of Chemistry ; by M. M. Pat- 
Tison Murr, M.A., F.R.S.E. 488 pp. 8vo. Cambridge, 1884, 
(University Press).—This is a volume of much more than ordi- 
ary importance among recent contributions to chemical litera- 
ture. Excellent books are not wanting in which chemical facts 
are presented, but a profound and thorough work upon Chemical 
Philosophy, suited to the wants of a student who has learned and 
digested these facts, has long been needed and this want is well 
supplied by the present volume. The subject is divided into two 
parts, Chemical Statics and Chemical Kinetics. Under the first 
are discussed the subjects of atoms and molecules, of atomic and 
molecular systems, the periodic law, and the applications of phy- 
Sical methods to problems of chemical statics. Under the second 
the leading heads are dissociation, chemical change and chemical 
finity. The work is full of suggestive matter and will aid all 
Students who are desirous of mastering the fundamental principles 
of modern chemistry. It is especially full in its references to 
recent work in the department of chemical physics. 
9. An Introduction to the Study of Organie Chemistry; by 
. 
to students in this country a volume which has met with such 
marked success in German 
umerous experiments, mostly of very simple character, are 
described which the student is expected to perform for himself. 
e possibility of basing a Kinetic The 8 
upon that there is a repulsive force between molecules—the hy- 
pothesis of elastic spheres being mechanically equivalent to the 
hypothesis of a repulsive force which for distances greater than 
gs 
