SCIENTIFIC SUMMARY. 
535 
PHYSICS, 
LIGHT, PHOSPHORESCENCE, AND HEAT 
HE subject of prismatic analysis still continues to attract attention. 
Dr. W. A. Miller has been lecturing on this subject to the Pharma- 
ceutical Society of London, and Dr. Roscoe at the Royal Institution of 
London and elsewhere. 
Some degree of variability, if it may be so expressed, has been observed 
by several investigators in the spectra of the earthy alkalies , on subjecting 
those substances to high and variable temperatures, and this variation has 
been examined by Professors Roscoe and Clifton, and the explanation 
they suggest of this variation is, that at the temperature of a gas-flame the 
spectrum of the oxide of the substance is seen, whilst at the higher tem- 
perature of the voltaic arc the oxide is decomposed and the spectrum of the 
elementary substance itself is seen. 
M. Morren has been examining the phosphorescence of rarefied gases 
and finds — ,1st, that pure and dry ox3’-gen, however rarefied, is never phos- 
phorescent by the passage of electric sparks ; 2nd, that any other gas, 
whether simple or compound, if pure and rarefied, never shows the pheno- 
menon of phosphorescence ; 3rd, a mixture of oxygen and nitrogen exhibits 
feeble and transient phosphorescence, and more distinctly if a little vapour 
of ordinary nitric acid is added ; but if a small quantity of either fuming 
or anhydrous sulphuric acid is added, the phosphorescence is splendid and 
durable ; 4th, a similar beautiful result is obtained by passing induction 
sparks through a rarefied mixture of 200 parts oxygen, 150 sulphurous 
acid, and 100 nitrogen ; and, 5th, the phosphorescence is produced by the 
decomposition and recomposition of the crystallized body produced in the 
manufacture of oil of vitriol ; viz., NO 3 , 2 SO 3 . Anhydrous sulphuric 
acid is probably the seat of this luminosity. 
The subject of phosphorescence has also been recently investigated by 
M. 0. Fiebig, particularly with regard to the influence of heat upon this 
property of bodies. He has found that when a solution of aesculine is 
gradually heated, the blue tint first becomes deeper and more violet, then 
it becomes paler, and at about 50 degrees it can hardly be distinguished 
from the ordinary tint. By further heat, the tint lessens in intensity and 
becomes pale green, and that, with a solution of quinine similarly treated, 
the tint lessens in intensity as it approaches the boiling-point ; and, in 
both liquids, cooling reproduces the original colour. He also found that 
fluoride of calcium possesses the property of becoming phosphorescent 
by the action of heat after a previous insolation, and that this property 
remains after the loss of colour. 
Professor Rankine, of Glasgow, has described, in the Philosophical 
Magazine, a dew-bow, which he saw on the surface of mud, in a by-road 
near Glasgow, on the 13tli of February last ; he states, “that its colours 
were complete from red to violet, and very bright and distinct, especially 
where the mud was softest and moistest ; where a sheet of water, how thin 
soever, covered the mud, the iris vanished. No trace of an iris could be 
seen on the grass, in the sky, or anywhere but on the mud ; and on those 
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