46 WRITINGS OP JAMES SMITUSON. 



the discoverer of it, ought to bo held in some degree sacred, 

 and not altered without the most urgent necessity for doing 

 it. It is but a feeble and just retribution of respect for the 

 service which he has rendered to science. 



Professor Struve, of Lausanne, whose skill in miner- 

 alogy is well known, having mentioned to me, in one of his 

 letters, that from some experiments of his own, he was led 

 to suspect the existence of phosphoric acid in several stones, 

 and particularly in the zeolite of Auvergne, I have directed 

 my enquiries to this point, but have not found the phos- 

 phoric, or any other acknowledged mineral acid, in this 

 zeolite. 



Many persons, from experiencing much difficulty in com- 

 prehending the combination together of the earths, have 

 been led to suppose the existence of undiscovered acids in 

 stony crystals. If quartz be itself considered as an acid, to 

 which order of bodies its qualities much more nearly assim- 

 ilate it, than to the earths, their composition becomes readily 

 intelligible. They will then be neutral salts, silicates, either 

 simple or compound. Zeolite will be a compound salt, a 

 hydrated silicate of alumina and soda, and hence a com- 

 pound of alumina not very dissimilar to alum. And topaz, 

 whose singular ingredients, discovered by Mr. Klaprotu, 

 have called forth a query from the celebrated Mr. Vauque- 

 LiN, with regard to the mode of their existence together,* 

 will be likewise a compound salt, consisting of silicate of 

 alumina, and fluate of alumina. 



Our acquaintance with the composition of the several 

 mineral substances, is yet far too inaccurate to render it 

 possible to point out with any degree of certainty, the one 

 of which zeolite is an hydrate, however the agreement of 

 the two substances in the nature of their constituent parts, 

 and in their being both electrical by heat, directs conjecture 

 towards tourmaline. 



St. James's Place^ Jan. 22, 1811. 



* Annales du Museum d'Hist. Nat. tome 6, p. 24. 



