280 Dr. J. E. Reynolds on certain Mineral Silicates. 



I am well aware that the mode of regarding the native silicates 

 proposed in this paper is not likely to be considered with much 

 favour by those chemists who, with Von Kobell*, dislike the 

 idea of innovation, or others who, with Naquet-f, appear to be 

 disposed to place no limit to the power of condensation and suc- 

 cessive dehydration of the polysilicic acids. I have therefore 

 sought for such experimental evidence as might be expected to 

 throw any light upon the subject, and hope soon to be able to 

 communicate the results of some experiments in a new direction 

 which promise to give a clue to the modes to be adopted in dis- 

 tinguishing the different conditions of SiO 2 throughout some of 

 their compounds. Much independent evidence, however, is 

 forthcoming; and I will now proceed to show that the composi- 

 tion of the natural and artificial hydrates of SiO 2 can be easily 

 and simply explained in accordance with the principles already 

 stated — and then, that the relations of the native anhydrous salts 

 become apparent when their formulae are treated in a similar 

 manner. 



Silicic Hydrates. 



1. Hydrates of SiO 2 . — FranklandJ states that the normal hy- 

 drate (1) is the body separated from a soluble silicate by treat- 

 ment with a stronger acid. Professor Graham's compound (2) 

 corresponds well to the formula of the dibasic acid§. 



\Si / \ Si / 



(1) H^X 02 and ( 2 ) H 2 X° 



In the absence of distinct evidence to the contrary, we may 

 regard the above as silicic hydrates uncondensed. All the 

 salts of the uncondensed SiO 2 are formed on one or the other of 

 the above types. 



We have now the second great division of the silicic hydrates 

 and metallic salts, i. e. that comprising the hydrates of SiO 6 

 = 3 (SiO 2 ), or a simple multiple of this. 



2. Hydrates of SiO 6 '. — (a) First amongst these hydrates stands 

 that prepared and analyzed by Doveri|| ? and which may be well 



\Si/ 

 represented by the formula H 2 VO- This corresponds precisely 



/O e \ 



to Graham's hydrate of the uncondensed acid. 



* Journal fur pralctische Chemie, 1859, p. 168. f Op. cit. 



% Lecture Notes, p. 101. 



§ Philosophical Transactions, 1861, p. 204. 



i| Ann. de Chim. et de Phys. (3) vol. xvi. p. 129. 



