Geology and Mineralogy. 487 
drical vessel containing the magnetic substance under considera- 
tion. He discusses the method ‘by t the aid of the theory of poten 
tials and obtains for an aqueous solution of chloride of iron of 
density 1°475 a magnetizing constant of -K = 0:0000815.—J2., 
(3.) Hanxet discusses the results of previous experiments upon 
the electrical effect of light rays upon metal plates, immersed in 
fluids, and adds some experiments of his own which show that the 
difference of potential of certain metal plates immersed in fluids 
is assert altered by light; and that in certain cases this effect 
is opposite to that caused by the heat rays.— 
4.) Cuausius shows that if there are a number of condueting 
bodies C,, C,, C,, ete. which influence each other and if these 
bodies are first char ged with the quantities of electricities Q,, 
Q,, Q, ete. giving the potentials Mig V,, V, etc., and afterwards 
charged with the page co 2, Diyas wi ith the ——— 8, 
B,, B,; the equation [VQ=2[8Q results.—J0., 
.) Herman Herwie collects the facts in leeks 8 ‘the differ- 
ent mechanical actions of positive and negative electrical poles; 
joins to these some observations of his own in regard to the 
havior of flames placed between their poles, and discusses the 
generality of these phenomena together with their bearing upon 
the tywo-fluid theory of electricity. ie p. 516. 
6.) According to an investigation of W. von Muncumavsen 
carried on in the laboratory of A. Wullner, the _ heat of 
water et . is represented by the sg, ese me pie _ 
Ib., p. 5 
II. Geology AND MINERALOGY. 
, by Frerpinanp FREIHERRN VON Ri ICHTHOFEN. 
auspices of the Prussian Government. nly a few prominent 
points in Chi ina were heotere - interior of the country not being 
aiping rebellion. He also went to 
Siam, Formosa, the Bhitipy ‘ipnines Celebes and Java. Japan was 
not at the time open to foreigners. 
The year 1867 and part of 1868 were spent in California, in con- 
nection with the Geological Survey of that State under J. 
Whitney; and av volume treating learnedly of the N atural Sys- 
tem of volcanic rocks, and describing those of Western North 
America was one result of his labors. 
In July, 1868, he left for a second fe Chis: ai was there 
- Pe pea Ergebnisse eigener Reisen at darauf gegriindeter Studien; von 
a RICHTHOFEN. Erster Band. Rinleitender Theil. 
ND FREIHE VON 
fon 1877, (Verlag von Dietrich Reimer, 
