THE TllANsrORT AND STORING OF NITRO-GLYCERINE. 
307 
an ignited solid. If, however, the vaporous matter does not contain solid particles in a 
free or concrete form, the ignition of it produces only certain tints of the spectrum, and 
hence its variable colours. Examined, therefore, with a prism, we see only those bands 
of colour which are characteristic of the flame. 
I will show you this by moistening little balls of coke with the chlorides of the fol- 
lovv'ing metals, and then introducing them into the colourless flame of a Bunsen burner, 
or, better still, into that of Griffin’s blast jet; and you note how different are the tints, 
and how they fail to illuminate certain colours of these dyed ribbons. 
Chloride of sodium gives a rich yellow flame. 
Chloride of copper „ a deep blue-green flame. 
Chloride of strontium „ a rich scarlet flame. 
Chloride of barium „ a pale pea-green flame. 
Chloride of lithium „ a bright crimson flame. 
And a salt of thallium „ a beautiful grass-green flame. 
The chlorides are used because they are the most volatile, and they exist in the flame 
in a vaporous condition. These tints are so characteristic of the several metals, that 
they afford the most delicate means of discovering their presence ; but the great fact 
which modern investigations have brought out is the circumstance that the spectrum of 
these flames consists of certain well-defined and constantly-placed bands of colour. This 
diagram will show you the spectra of the metals which I have been using; and so true and 
constant are the positions and tints of these bands, and so delicate are the manifestations 
of them, that they become the means of discovering the merest traces of the several 
metals. But I must not pursue this further, except by showing you the differences in 
the tints of this spectrum and ribbons when examined with the pure white light of 
burning magnesium. 
And now I will briefly describe the contrivances which are used for increasing, or 
rather, I should say, for fully developing, the temperature of burning gas. I have 
shown you that the light of a flame depends on the presence of ignited carbon; if, 
therefore, by any contrivance we can at once burn this carbon, and not permit it to stand 
as it were idle,in an ignited condition, the temperature must be considerably increased. 
This is the principle concerned in all the contrivances for developing the heat of gas. 
One of the simplest means of accomplishing this is to mix a sufficient quantity of air 
with the gas before it reaches the place of combustion ; and this is easily done by 
putting a cap of wire gauze upon the chimney of an Argand burner, and setting fire 
to the gas above it. The effect of this arrangement is that, as the gas passes from the 
burner to the top of the chimney, it draws in a quantity of atmospheric air, which freely 
mixes with it and burns the solid particles. The same is the case with the burner of 
Bunsen, which I have already described ; and you will note how strongly it ignites this 
platinum crucible. The same arrangement is adopted by Mr. Griffin in his reverbera¬ 
tory furnace, which is a Bunsen’s burner enclosed in a clay chamber. I have here 
another contrivance of the same nature, called an atinopyre, which is used by Professor 
Hofmann in his furnace for effecting organic analysis. It is a hollow cylinder of baked 
pipeclay pierced with a large number of small holes. When it is placed on a small fish¬ 
tail burner, the gas, in issuing from the holes, draws in a sufficient quantity of atmo¬ 
spheric air to make it burn at all the apertures with a clear blue light; and thus the 
temperature is so much increased that the entire body of the numerous cylinders com¬ 
posing the furnace becomes almost white hot. 
(7’o he continued.) 
THE TEANSPOKT AND STOKING OF NITKO-GLTCERINE. 
The annexed report has been issued to the underwriters by Lloyd’s Salvage As¬ 
sociation, in reference to the explosiveness of nitro-glyccrine, or glonoin oil:—“ When 
intelligence reached this country of the calamitous destruction of life and property 
caused by the explosion on board the ‘European,’ applications from many quarters were 
made to the Association to investigate the circumstances. A general belief existed that 
the accident was occasioned by a new combustible substance, hitherto unknown to com- 
