gO FRAGMENTS OF SCIENCE. 
The remark already made, as to the bearing of the 
decomposition of nitrite of amyl by light on the question 
of molecular absorption, applies here also; for were the 
absorption the work of the molecule as a whole, the iodine 
would not be dislodged from the allyl with which it is 
combined. The non-synchronism of iodine with the 
waves of obscure heat is illustrated by its marvelous trans- 
parency to such heat. May not its synchronism with the 
waves of light in the present instance be the cause of its 
divorce from the allyl? 
Iodide of Isopropyl. The action of light upon the vapor 
of this liquid is, at first, more languid than upon iodide of 
allyl; indeed many beautiful reactions may be overlooked, 
in consequence of this languor at the commencement. 
After some minutes' exposure, however, clouds begin to 
form, which grow in density and in beauty as the light 
continues to act. In every experiment hitherto made 
with this substance the column of cloud filling the experi- 
mental tube was divided into two distinct parts near the 
middle of the tube. In one experiment a globe of cloud 
formed at the center, from which, right and left, issued 
an axis uniting the globe with two adjacent cylinders. 
Both globe and cylinders were animated by a common 
motion of rotation. As the action continued, paroxysms 
of motion were manifested; the various parts of the cloud 
would rush through each other with sudden violence. 
During these motions beautiful and grotesque cloud-forms 
were developed. At some places the nebulous mass would 
become ribbed so as to resemble the graining of wood; a 
longitudinal motion would at times generate in it a series 
of curved transverse bands, the retarding influence of the 
sides of the tube causing an appearance resembling, on a 
small scale, the dirt-bands of the Mer de Glace. In the 
anterior portion of the tube those sudden commotions 
were most intense; here buds of cloud would sprout forth, 
and grow in a few seconds into perfect flower-like forms. 
The cloud of iodide of isopropyl had a character of its own, 
and differed materially from all others that I had seen. A 
gorgeous mauve color was observed in the last twelve inches 
of the tube; the vapor of iodine was present and it may 
have been the sky-blue scattered by the precipitated par- 
ticles which, mingling with the purple of the iodine, pro- 
duced the mauve. As in all other Quses here adduced, the 
