NEW CHEMICAL ftE ACTIONS. 81 
effects were proved to be due to the light; they never 
occurred in darkness. 
The forms assumed by some of those actinic clouds, as I 
propose to call them, in consequence of rotations and other 
motions, due to differences of temperature, are perfectly 
astounding. I content myself here with a meager de- 
scription of one more of them. 
The tube being filled with the sensitive mixture, the 
beam was sent through it, the lens at the same time being 
so placed as to produce a cone of very intense light. Two 
minutes elapsed before anything was visible; but at the end 
of this time a faint bluish cloud appeared to hang itself on 
the most concentrated portion of the beam. 
Soon afterward a second cloud was formed five inches 
farther down the experimental tube. Both clouds were 
united by a slender cord of the same bluish tint as them- 
selves. 
As the action of the light continued, the first cloud 
gradually resolved itself into a series of parallel disks of 
exquisite delicacy, which rotated round an axis perpen- 
dicular to their surfaces, and finally blended to a screw 
surface with an inclined generatrix. This gradually 
changed into a filmy funnel, from the narrow end of 
which the 'cord" extended to the cloud in advance. The 
latter also underwent slow but incessant modification. It 
first resolved itself into a series of strata resembling those 
of the electric discharge. After a little time, and through 
changes which it was difficult to follow, both clouds pre- 
sented the appearance of a series of concentric funnels set 
one within the other, the interior ones being seen through 
the outer ones. Those of the distant cloud resembled 
claret-glasses in shape. As many as six funnels were thus 
concentrically set together, the two series being united by 
the delicate cord of cloud already referred to. Other cords 
and slender tubes were afterward formed, which coiled 
themselves in delicate spirals around the funnels. 
Kendering the light along the connecting-cord more 
intense, it diminished in thickness and became whiter; 
this was a consequence of the enlargement of its particles. 
The cord finally disappeared, while the funnels melted 
into two ghost-like films, shaped like parasols. They 
were barely visible, being of an exceedingly delicate blue 
tint. They seemed woven of blue air. To compare them 
