94 WRITINGS OF JAMES 8MITHS0N. 



In tho same way the unequal fusibility of two substances 

 may probably, on some occasions, bo ascertained ; and serve 

 from deficiency of a better, as a means of distinction be- 

 tween them. 



I am, sir, yours, &c. 



J. Smithson. 



ON SOME COxMPOUNDS OF FLUORINE. 



From Thomson's Annals of Philosophy, Vol. XXIII ; New Series, Vol. 

 VII, 1824, p. 100. 



January 2, 1824. 



Sir: When numberless persons are seen, in every direc- 

 tion, pursuing a subject with the utmost ardour, it is natu- 

 ral to conclude that their labors have accomplished all that 

 was within their reach to perform. 



It must, therefore, in mineralogy be supposed, that those 

 substances whose abundance has placed them in every hand, 

 have been fully scrutinized, and are thoroughlj' understood ; 

 and that if now to extend the boundaries of the science it 

 is not indispensable to explore new regions of the earth, 

 and procure matters hitherto unpossessed, it is yet only to 

 objects the most rare, the most difficult of acquisition, that 

 inquiry can be applied with any hope of new results. 



A want of due conviction that the materials of the globe 

 and tho products of tho laboratory are the same, that what 

 nature aflbrds spontaneously to men, and what the art of 

 the chemist prepares, differ no ways but in the sources from 

 whence they are derived, has given to the industry of the 

 collector of mineral bodies an erroneous direction. 



What is essential to a knowledge of chemical beings has 

 been left in neglect; accidents of small import, often of 

 none, have fixed attention — have engrossed it ; and a fertile 



