524 
liquid film, 94; on the self-regu- 
lation of the compound dynamo, 
462. 
Rutley (F.) on fulgurite, 389; on 
brecciated porfido-rosso-antico,393. 
Salt-solutions, on supersaturation of, 
453. 
Sarasin (E.) on the penetration of 
daylight in the water of the Lake 
of Geneva, 70. 
Selenium, on the electromotive action 
of illuminated, 315. 
Selenium-actinometer, on a, 251. 
Siemens (W.) on the theory of mag- 
netism, 237 ; on the electromotive 
action of illuminated selenium, 
316. 
Silver chloride, bromide, and iodide, 
on combinations of, with colouring- 
matters, 229. 
Spectrum analysis, lecture-experi- 
ments on, 365. 
Stalactite, on the formation of a, by 
vapour, 395. 
Steel, on the magnetic permeability 
of, 73, 338. 
Supersaturation, 
453. 
Teall (J. J. H.) on the metamor- 
phism of dolerite into hornblende- 
schist, 145. 
Telescope, on a monochromatic, 446. 
Temperatures, on the means of pro- 
ducing exceedingly low, 65. 
Thermoelectric circuits, on, 448. 
properties of amalgams, on the, 
observations on, 
Thermoelectricity of molten metals, 
on the, 495. 
INDEX. 
Thermoelectro-photo-baric unit, on 
the, 517. 
Thompson (C.) on the determination 
of chemical affinity in terms of 
electromotive force, 1, 102, 197. 
Trimethylamine, on the synthesis of, . 
from coal-gas, 232. 
Trowbridge (J.) on the measurement 
of strong electrical currents, 896 ; 
on the application of photography 
to electrical measurements, 513; 
on the production of alternating 
currents, 516. 
Voltaic and thermovoltaic constants, 
on, l. 
Voltaic cell, on the seat of the elec- 
tromotive forces in the, 153, 254, 
340. 
circuits, on the paths of electric 
energy in, 487. 
Williams (G.) on the synthesis of 
trimethylamine and pyrrol from 
coal-gas; and on the occlusion of 
hydrogen by zine dust, 232. 
Wilsing (Dr. J.) on the application 
of the pendulum to the determina- 
tion of the mean density of the 
earth, 219. 
Worthington (A. M.) on a capillary 
multiplier, 43; on the theory of 
pendent drops, 46; on Prof. 
Edlund’s theory that a vacuum is 
a conductor of electricity, 218. 
Wright (Dr. C. R. A.) on the deter- 
mination of chemical affinity in 
terms of electromotive force, 1, 
102, 197. 
Zine dust, on the occlusion of hydro- 
gen by, 282. 
END OF THE NINETEENTH VOLUME. 
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Pe ee 
