n associated with the experimental tube was depressed
only five inches, the action was not nearly so rapid as when the tube
was full. In such cases, however, it was exceedingly interesting to
observe, after some seconds of waiting, a thin streamer of delicate
bluish-white cloud slowly forming along the axis of the tube, and
finally swelling so as to fill it.

Fig. 2.

Fig. 3.

When dry oxygen was employed to carry in the vapour the effect was the
same as that obtained with air.

When dry hydrogen was used as a vehicle, the effect was also the same.

The effect, therefore, is not due to any interaction between the
vapour of the nitrite and its vehicle.

This was further demonstrated by the deportment of the vapour itself.
When it was permitted to enter the experimental tube unmixed with air
or any other gas, the effect was substantially the same. Hence the
seat of the observed action is the vapour.

This action is not to be ascribed to heat. As regards the glass of
the experimental tube, and the air within the tube, the beam employed
in these experiments was perfectly cold. It had been sifted by
passing it through a solution of alum, and through the thick
double-convex lens of the lamp. When the unsifted beam of the lamp
was employed, the effect was still the same; the obscure calorific
rays did not appear to interfere with the result.

My object here being simply to point out to chemists a method of
experiments which reveals a new and beautiful series of reactions, I
left to them the examination of the products of decomposition. The
group of atoms forming the molecule of nitrite of amyl is obviously
shaken asunder by certain specific waves of the electric beam, nitric
oxide and other products, of which the _nitrate_ of amyl is probably
one, being the result of the decomposition. The brown fumes of
nitrous acid were seen mingling with the cloud within the experimental
tube. The nitrate of amyl, being less volatile than the nitrite, and
not being able to maintain itself in the condition of vapour, would be
precipitated as a visible cloud along the track of the beam.

In the anterior portions of the tube a powerful sifting of the beam by
the vapour occurs, which diminishes the chemical action in the
posterior portions. In some experiments the precipitated cloud only
extended halfway down the tube. When, under these circumstances, the
lamp was shifted so as to send the beam through the other end of th