INDEX. 313 



Sulphur: dimorphism and allotropism of, i. 16 



combination of chlorine with sulphur, i. 20 



atomic weight of. compared with that of hydrogen, i. 100, 105 



its analogous properties with selenium and tellurium, i. 105 



spectrum analysis of, in different temperatures, i. 144 

 Sulphuretted hydrogen gas, i. 16 



Sulphurous acid, amount of absorption of radiant heat by, i. 41 

 Sun, probable cause of the light and heat of the, i. 28 



probability of the periodic connection of the solar spots with mag- 

 netic phenomena, i. 30, 31 



amount of force exerted by the sun's light within the limits of the 

 terrestrial atmosphere, i. 34 



chemical action of the light of the sun, i. 56 



effect of the opalescence of the atmosphere on the chemical power 



of the sun's light, i. 57 

 Sun, spectrum of the, i. 58 



thirteen terrestrial substances in the sun's atmosphere, i. 59 



metals shown by M. Kirchhoff to exist in the sun, i. 151-153 



and those proved not to exist in it, i. 154 



the structure of the sun in some respects still a mystery, i. 164 



the luminous gaseous atmosphere of the, i. 164 



mottled appearance of the photosphere of the sun, i. 164, 165 



the faculae, i. 165 



the red flames or protuberances round the edge during a total 

 eclipse, i. 165 



the solar spots, i. 166 



their periodicity, i. 166 



appear to be influenced by the planet Venus, i. 166 

 Sun-rise and sun-set, causes of the bright tints at, i. 58 

 Surirella, mode of development of, i. 202 

 Synapta, structure of the genus, ii. 185 

 Synapta digitata, structure and habitat of the, ii. 1 85 

 Syncladei, structure of the branches of, i. 328 

 Syncoryna Sarsii, structure and development of zooids of, ii. 90 

 Synthesis, in the animal and vegetable creation, i. 96 



Taenia, or tape-worm, structure and mode of reproduction of, ii. 145 



transformation of the young of, ii. 146. 

 Tsenioidae, characters of, ii. 144 



