Iodo-chloride of Silver Emulsion.--By V. SCHUMANN 7458
Apparatus for Saturating Water with Sulphurous Acid.--1
engraving. 7458
IV. PHYSICS, ELECTRICITY. ETC.--The Wave Theory of Light.--By
SIR WM. THOMSON.--Sound and light due to wave
vibrations.--Difference between vibrations of light and
sound.--Radiant heat.--Solar spectrum.--Luminiferous
ether.--How to measure wave lengths of light and the frequency
of vibrations.--With diagrams. 7448