NEW CHEMICAL REACTIONS. 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. 



Rendering 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 



