442 The effects of Light on the Germination of Seeds. 



Art. II. The effects of Light on the Ger7mnation of Seeds, 

 6^c., when passed through media of various colors. By 

 R. B. L. . 



(Continued from page 400.^ 



When we look on a spectrum which has been subjected to 

 the influence of some absorptive medium, we must not con- 

 clude from the colored rays which we see, that we have cut 

 off all other influences than those that belong to those par- 

 ticular colors. Although a blue glass or fluid may appear to 

 absorb all the rays except the most refrangible ones, which 

 have usually been considered as the least calorific of the 

 solar rays, yet it is certain that some principle has permeated 

 the glass or fluid, which has a very decided and thermic 

 influence ; and so with regard to media of other colors. 



" As we have previously remarked that the relative tempera- 

 tures indicated by good thermometers, placed behind the 

 fluid cells and glasses, will place this in a clearer light, the 

 following tabular view of a series of results may be said to 

 mark distinctly the relative degrees in which these media are 

 permeable by the heating rays: — 



GLASSES. 



Color. Rays not absorbed. Temperature. 



1. Ruby. Ordinary red and extreme red. . . 87° 



2. Red. Ordinary red, orange 83 



3. Orange. Blue, green, yellow, orange red, and ex- 



treme red. ..... 104 



4. Yellow. Red, orange, green and blue. , , . 88 



5. Blue. Violet, indigo, blue, green and some red. 94 



6. Green. Orange yellow, green and blue. . . 74 



FLUIDS. 



A. Red. Ordinary and extreme red. ... 78 



B. Yellow. Ordinary red and yellow. ... 80 



C. Green. Blue, green, yellow, orange. . . 69 



D. Blue. Green, blue, indigo, violet and trace of 



red 73 



E. White- All the rays • . 89 



