CONTENTS OF VOL. XIX.—FIFTH SERIES. Vv 
Page 
Notices respecting New Books :— 
Mr. M. M. Pattison Muir’s Treatise on the Principles of 
DRS eso) 1S SI a Hig ad AAS ata dl ales 222 
Proceedings of the Geological Society :— 
Mr. A. J. Jukes-Browne on the Boulder-clays of Lincoln- 
NEE RE trae aj Side Wisk bee ace he a dle « Ol 225 
Mr, J. H. Collins on the Geology of the Rio-Tinto Mines, 
with some general Remarks on the Pyritic Region of 
Mae IAP NIOLOND ..p¥:cis' Ai. esis dRy onln as SUE ale whe 227 
Mr. J. W. Judd on the Tertiary and Older Peridotites of 
Be MGR e sey =o fe nec dN ww alen Wren ee ay ds 228 
Mr. T. Mellard Reade on the Boulders wedged in the 
Falls of the Cynfael, Ffestiniog ..:.....5...5..64. 229 
On Combinations of Silver Chloride, Bromide, and Iodide with 
Colouring-Matters, by M. Cary Lea, Philadelphia ........ 229 
On a Selenium-Actinometer, by M. H. Morize, of Rio Janeiro. 231 
On the Synthesis of Trimethylamine and Pyrrol from Coal- 
gas; and on the Occlusion of Hydrogen by Zinc-dust, by 
Beemer taiinama. HORS s (aues Si oa s 2 AG eel Bate SRS 232, 
NUMBER CXIX.—APRIL. 
Werner Siemens’s Contributions to the Theory of Magnetism... 237 
Prof. O. J. Lodge on the Seat of the Electromotive Forces in 
ILE TLS1S CCL A ee ree oa ee er a eae 254 
Miss S. Marks on the Uses of a Line- ihendes SOP ere 280 
Dr. A. Macfarlane on the Logical Spectrum .............. 286 
Dr. J. Hopkinson on the Quadrant-Electrometer .......... 291 
Profs. W. E. Ayrton and J. Perry on the most Economical 
Potential-difference to employ with Incandescent Lamps .. 304 
On the Limit of the Density and on the Atomic Volume of 
Gases, and particularly Oxygen and Hydrogen, by E. H. 
OEM eae Hoth: Sich seo sala) 1a ye wets OE EI OA 313 
On the Electromotive Action of Illuminated Selenium disco- 
vered by Mr. Fritts of New York, by Werner Siemens.... 315 
NUMBER CXX.—MAY. 
Mr. J. C. M‘Connel’s Notes on the Use of Nicol’s Prism .... 317 
Mr. kh. H. M. Bosanquet on Electromagnets.—III. Iron and 
Steel. New Theory of Magnetism.........7...... 0045 333 
Prof. O. J. Lodge on the Seat of the Electromotive Forces in 
pit Onna, Cellsy. thay uw fei iS’. oid ete eae OGL PO 340 
Mr. E. Cleminshaw’s Lecture-Experiments on Spectrum Ana- 
lysis 
