<|g INFLUENCE OF LIGHT ON THE PROFAGATION OP SOUND. 



other fragments borrowed for this purpose were not so high, 



that of one being 7'63, of another 7'53, and of a third so low 



as 7-15. 



Thi« cannot be It is evident, tliat no variation of mere proportion of the 



Bwuio to uif- ingredients can acroiint for an increase of specific crravitv 

 fcirence m their " , • ,. ,> 



proportions. from 5\f)18 to 7'953, which are in the ratio oi 3 to 4 ; for 



since columbite contains four fifths oxide, if the whole re- 

 maining one fifth part in weight of that oxide could be sup- 

 posed added to the same bulk, without diminution of the 

 quantities of iron and manganese, the specific gravity would 

 not then exceed 7*1 : and even if a weight equal to one third 

 of the whole were thus added, without increase of bulk, 

 still the aggregate would not quite equal the heaA'iest tan- 

 talite in specific gravity ; but, on the contrary, the quantity 

 of white oxide in this specimen certainly does not amount 

 to six sevenths, and probably is not more than five sixths of 

 the whole mass. 

 Perhaps from The only chemical difference, by which this circumstance 

 iBodcof aegre- ^^^^^ ^^ explained, would be the state of oxidation, which 

 litioa, my experiments cannot appreciate; but it may also arise in 



part from actual cavities in the mass of columbite, and in 

 part from the state or mode of aggregation. 



IV. 



Inquiries concerning the Influence, that Light exerts on the 

 Propagation of Sound. By Modeste Parolette*. 



por-aut agent vJ'F all the objects that offer themselves to the contem- 

 iu natural phe- plation of the chemist and natural philosopher light is the 

 noblest. The action it exerts on all the combinations of 

 matter, its extreme divisibility, the rapidity of its propaga- 

 tion, and the part it takes in what constitutes the life of or- 

 ganic beings, lead us to consider it as a substance acting the 

 first part in the economy of nature. 



• Journal de Phisique, vol. LXVIII, p.34G. 



The 



