138 
POPULAE SCIENCE REVIEW. 
pass into another modification, and this change, with its accompanying de- 
velopment of heat, is continued in the calorimeter. 
(3.) If the substance investigated is porous, and (as was the case in the earlier 
methods) is directly immersed in the liquid of the calorimeter, in which case 
the development of heat which accompanies the moistening of porous sub- 
stances comes into play. — Vide a Paper read before the Royal Society, during 
the past session. 
The Examination of Minerals with the Spectroscope. — In the last number of 
the Dublin Quarterly J ournal of Science, we find an important paper on the 
subject of spectrum analysis, from the pen of Mr. Emerson J. Keynolds. 
Contrary to the opinion of Kirchoff, that the spectra* of a combination of 
salts are as distinct as the same when viewed separately, Mr. Keynolds 
declares that it can be easily shown that the spectrum afiforded by a mixture 
of salts depends to a great extent upon the relative proportions of the 
constituents of the mixture. If a chloride of any metal of the alkalies or 
alkaline earths be introduced into the flame of a Bunsen’s burner, it almost 
immediately commences to volatilise. The alkaline chlorides being more 
volatile than those of the alkaline earths, are first completely dissipated in 
vapour. Chloride of lithium is but little less volatile than chloride of 
sodimn. In Bunsen’s experiment (from which Kirchoff ’s conclusion was 
drawn), the quantities of the various chlorides composing the mixture were 
about equal ; thereupon the order in which the several spectra appeared 
seemed to indicate the relative degrees of volatility of the different chlorides. 
The sodium spectrum appeared first, and as it faded the lithium spectrum 
became visible ; but since the volatility of the lithium salt is but a little 
below that of chloride of sodium, some of the former must have volatilized 
with the first portion of sodium vapour, though it escaped detection. It was 
only when the sodium light diminished in intensity, that the hthium 
spectrum made its appearance, together with the spectra of potassium and 
barium. Hence the conclusion is inevitable, that “ if a sufficiently large 
amount of sodium were present in proportion to the chlorides of other metals, 
no spectrum but that of sodium would be obtained, and we should therefore 
fail to detect lithium or potassium, though they were actually present.” The 
only remedy which Mr. Keynolds proposes is the employment in doubtful 
cases of the inductive spark. — Vide Dublin Quarterly Journal of Science, 
July, 1864. 
Cheap Electric Lamp. — Mr. S. Highley, the philosophical instrument-maker 
of Green Street, Leicester Square, has just constructed a novel form of auto- 
matic regulator for the electric light which strongly recommends itself to 
the notice of the lecturer and experimentalist, as it is exceedingly sensitive in 
action, simple in construction so as to be little liable to get out of order, and 
very cheap, as with a sufficient number of cells of a new modification of 
battery it can be sold at a price that is usually charged for a Duboscq’s or 
Serrin’s regulator, per se, without battery power. The manufacturer of this 
arrangement calls it Malden’s Pneumatic Electric Kegulator, being in- 
debted to that gentleman for the novel principle of construction. A sectional 
view of the part is shown in the adjoining figure. The rod that supports the 
upper carbon is attached to a copper float, f, that rests upon a column 
of water, w, contained in a chamber that communicates by a small opening 
