6 WlLDE, Points of Chemical Philosophy. 



elements (with their beautiful gradation of properties) 

 constitute the foundation, and much the greater part of 

 the huge fabric of modern chemistry. 



As the luminous properties commonly attributed to 

 the alkaline-earth series of elements only become manifest 

 when in combination with elements of the halogen and 

 oxygen series, it may be maintained, with good reason, 

 that the extraordinary properties attributed to radium 

 really belong to the negative elements with which it 

 enters into combination. It is no refutation of the view 

 now advanced to say that the property of luminescence is 

 not manifested in all combinations of the negative 

 elements with the other elements. The phosphorescent 

 and other relations to light, heat, electricity, and mag- 

 netism of the halogen and oxygen series are too numerous 

 in inorganic, as well as in organic nature, to permit the 

 denial to them of a selective affinity for the manifestation 

 of properties now attributed almost exclusively to radium 

 and its congeners of the series H2n. It will be sufficient 

 if I mention in this connexion (i) the luminescence and 

 radio-active properties of phosphorus by its slow oxida- 

 tion, and (2) the phosphorescence of decaying organic 

 matter, and of many insects ; the most notable of the 

 latter being the Pyrophoriis noctilucus, the luminous 

 organs of which have been made the subject of experi- 

 ment by S. P. Langley and F. W. Very 1 . 



Macaire 2 , Matteucci 3 , Langley, and others agree that 

 the phosphorescence of insects is due to oxidation, and is 

 attended by the formation of carbon dioxide ; the light is 

 increased in oxygen, and extinguished in hydrogen and 



1 Amer. Journ. Science, vol, 40, p. 97, 1890. 

 Smithsonian Misc. Coll., vol. 41 (1258), p. 19, 1901. 



2 Bib. Univ. de Geneve, 1821. 



* Ann. de Chim. et de Phys., vol. 9, p. 71, 1843. 



