PROCEEDINGS OF THE POLYTECHNIC ASSOCIATION. 547 



boils at 190° C. It is the hydrate of the radical Si Cg H which 

 the authors call silicononyl. According to the new chemical 

 nomenclature, its name is eichilak. 



Action of Light upon Iodide of Silver. 



M. Carey Lea, in a paper on this subject in the American Jour- 

 nal of Science and Art for September, gives a statement of various 

 experiments, and concludes that the action of light upon pure iso- 

 lated iodide of silver cannot be a chemical reduction, because, 



1st. That effect, when carried many hundred thousand times 

 further than in the ordinary photographic process, perfectly dis- 

 appears in a few days, spontaneously, under circumstances which 

 render it impossible to suppose that iodine could have been 

 restored to replace that which (had the reduction taken place) 

 must have been diseno-ajred. 



2d, Even when the action of light is prolonged many hundred 

 thousand fold the ordinary time, no reduced silver nor sub-iodide 

 can be detected as at present. 



3d. He has shown that another metal, mercury, is capable of 

 developing images as well as silver. 



4th. He had endeavored to show that a purely physical cause, 

 to wit, mechanical pressure, is capable of producing a developable 

 impression, thereby answering the objection of the inadequacy of 

 a physical influence to create a basis of development. 



5th. Although the chemical theory is supported by some dis- 

 tinguished chemists of the present day, he was not aware that a 

 single well verified experiment had been brought forward in sup- 

 port of that view. 



Color of a Diajiond. 

 Fremy exhibited before the French Academy of Science a yel- 

 lowish diamond, which on being heated changes its color to rose 

 red; this it retains for two or three days, and gradually resumes 

 the light yellow. This peculiarity has increased its value to three 

 times that of the colorless gem of the same size. It is held at 

 $36,000. 



Heat Absorbing Power of the Vapor of Water. 



The report of the experiments of Magnus, puljlished in Pog- 



gendorf 's armalen^ has thrown new light on this subject. Tydall, 



in his lecture on radiation, had ascribed to watery vapor great 



absorbent power, and asserted that the power of a single mole- 



