Geological Society. pi) 
play during chemical operations. The thermo-dynamical methods 
of investigation introduced by Horstman, Gibbs, and others, and 
the electrical methods founded on the work of Joule and Thomson, 
and developed by Helmholtz and Wright, also enable us to gain 
some conceptions of the conditions under which chemical changes 
proceed and chemical equilibrium is established, and at the same 
time throw a little light on the most profound parts of chemical 
phenomena, the nature and conditions of action of the forces 
concerned in the combinations and decompositions of atoms.” 
The fair and cautious manner in which the author introduces 
all the ordinarily accepted theories, as well as those which are less 
known, is one of the excellent points of the book; whilst his 
parting advice, “to exhibit the hypotheses of Chemistry as at once 
arising from facts and serving as guides in the quest of facts,” 
is what all teachers and workers in our science will do well to bear 
in mind, remembering that one of the chief difficulties in ‘“‘ the use 
of chemical hypotheses consists in determining the limits of the class 
of phenomena to which each hypothesis can be applied.” 
In conclusion, we can commend Mr. Muir’s book most heartily to 
both teachers and taught as a reliable source of information on 
general chemical theory as well as on many points not easily found 
in the ordinary text-books, and the accounts of which as occurring 
in the original memoirs are generally in a too unwieldy condition 
for reference when time and opportunity are limited. We believe 
that no one will rise from a perusal of this book without feeling 
that his mind has become cleared on many points and his sym- 
pathies widened into taking a much deeper interest in those branches 
of the science with which he is not immediately concerned, whilst 
many will experience an increased desire to have a share in the 
solving of problems which have not yet yielded to the force of in- 
vestigation. As page after page is passed in review, we feel that we 
are indeed following in the “ very footprints of the discoverers.” 
THos, CARNELLEY. 
XXVIII. Proceedings of Learned Societies. 
GEOLOGICAL SOCIETY. 
[Continued from p. 148.] 
January 28, 1885.—Prof. T. G. Bonney, D.Sc., F.R.S., President, 
3 in the Chair. 
oe following communications were read :— 
1. “ The Boulder-clays of Lincolnshire : their Geographical Range 
and Relative Age.” By A.J. Jukes-Browne, Esq., B.A., F.G.S. 
The author commenced by referring to the late Mr. Searles V. 
Wood’s papers on the Glacial beds of Yorkshire and Lincolnshire, 
and stated, as the result of his own investigations, that two distinct 
types of Boulder-clay occur in Lincolnshire, (1) the grey or blue 
