146 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



intensity of the light under test, in terms of the standard, or 

 unit, which in France is always the Carcel burner, consum- 

 ing forty grammes of colza oil. This French unit is estimated 

 to be equal to between nine and a half and eleven and a half 

 of the English units or candles. Elliot' 's European Light- 

 house System, p. 183. 



THE EEFLECTIOX OF LIGHT. 



An almost exhaustive historical essay, by Lundquist, on 

 the investigations of earlier physicists into the peculiarities 

 of the light reflected from the surfaces of solid bodies, is sup- 

 plemented by observations made by himself on the reflection 

 from fuchsin and some other substances. The methods fol- 

 lowed by him were similar to those adopted of late years by 

 Jamin, Wiedemann, Van der "Willigen, and others. A nar- 

 row pencil of sunlight, reflected in a fixed horizontal direc- 

 tion from a heliostat, passes successively through an achro- 

 matic lens, a flint-glass prism, and a polarizing Nicol's prism, 

 and falls upon the reflecting surface of fuchsin ; the reflected 

 light is then analyzed by a compensator and a second Nicol's 

 prism. Rays of light from seven different portions of the 

 spectrum were examined ; and Lundquist concludes that, in 

 respect to the principal angle of incidence, fuchsin comports 

 itself as does indigo, and the observations are represented 

 by the theoretical formulae for metallic reflection so long as 

 the angle of incidence is Greater than 50. The author's in- 

 vestigation into the intensity of the reflected light shows 

 that, on the one hand, the intensity is always slightly less than 

 that computed, and that, on the other hand, the quantities 

 reflected vary sensibly with the color of the incident light, 

 so that when white light falls upon the fuchsin the color of 

 the reflected ravs varies witli the anode of incidence. The 

 power of the substance to absorb different colored rays offers 

 a remarkable anomaly, as, while the yellow light is reflected 

 in greater proportion than the blue, it is absorbed in less pro- 

 portion. Poggendorff Annalen, CLIL, 595. 



THE ACTION OF LIGHT UPON CHLOROPHYLL. 



It has been long known that alcoholic extracts of chloro- 

 phyll are decomposed rapidly in the sunlight, but slowly in 

 diffused daylight, and in even the faintest light assume vari- 



