SCIENTIFIC SUMMARY. 
519 
out some of the finer and characteristic lines, complicated electrical appa- 
ratus has hitherto been employed. Crookes, however, has shown, that by 
employing the metallic compounds in the form of chlorates, many, if not 
all, of these brilliant appearances can be produced with the ordinary gas 
flame. He describes the greatly-improved appearance which is thus ob- 
tained when baryta, strontia, lime, potash, soda, and lithia are examined 
in this way, the brilliant blue line of the latter metal being distinctly visible. 
The spectra of many of the heavy metals, which cannot usually be seen 
except with the electric light, can also be submitted to examination. 
Professor Zantedeschi, of Padua, is of opinion that the lines in Fraun- 
hofer’s spectrum are not all fixed ones, but that some of them are variable. 
And the general tendency of recent examinations of solar and other spectra 
is to show that prismatic analysis is not of that absolute and unchangeable 
character as was at first supposed, but that it is subject, to a small extent, 
to conditions of temperature, &c. 
M. J. M. Leguin has examined the spectra of phosphorus and sulphur 
by volatilizing those substances in a current of hydrogen. The vapour of 
phosphorus in hydrogen gives a red ray ; an orange ray almost as visible 
as the red ; two less distinct green rays at the more refrangible end of the 
visible part of the green ; and, at a comparatively dark interval, a bluish- 
green ray ; then some feeble blue or violet rays. Of these, the red and 
bluish-green rays probably belong to the hydrogen. In the sulphur spectrum 
there is a red ray, and three distinct and nearly equidistant green rays. 
The three green rays are the most prominent part of the spectrum of sul- 
phur ; they were seen with unmistakable precision in sulphuretted hydro- 
gen and sulphurous acid. 
The same investigator, in a note to the French Academy of Sciences, 
“ On the Spectrum of the Electric Spark in Compound Gases,” states that 
the spectrum of fluoride of silicium exhibits a large vivid blue ray, very 
farfrom the green ; and the spectrum of fluoride of boron gives similar results; 
and he therefore attributes this blue ray to fluorine. He states that, whilst 
chemical decomposition is being produced in compound gases by the elec- 
tric spark, the bands in their spectra are not distinct, and the spark is enve- 
loped by a halo ; but when the compound gas is nearly all decomposed, 
the spark becomes slender, and the bands in the spectrum much more 
distinct.'" 
The line of demarcation between organic and inorganic chemistry, sharp 
and well-defined up to a recent period, is now gradually disappearing. 
Organic chemistry was originally held to include all chemical compounds 
which required vital force for their production, whilst inorganic che- 
mistry treated of all bodies which were capable of being built up from 
their elements by artificial means. Of late years the progress of science 
has placed us in possession of means of forming synthetically a vast num- 
ber of purely organic compounds ; and the International Exhibition con- 
tains, amongst the chemicals in the French department, some of the most 
remarkable products which have ever been formed in this way. M. Ber- 
thelot exhibits here, for the first time, alcohol, stearin, and other natural 
# See also c: Physics.’ 
2 N 2 
