368 Dr. OcUing' on Ortho- and Meta-silicates, 



Zi + 1 n — b 



"'-'n-b b 



_ (& + !)(/> + 2) (n-b-^- 

 '^^~{n-b){n-b-\)\ b J' 



''^-(^-l,)^n-b-l){n~-b-^)\ b ;>«"^«0«"- 

 These results might have been obtained more directly by 

 neglecting a from the fii'st. If the number of years was large, 

 we should have very nearly the probability of Aj presenting 

 the phfenomenon and Ag not doing so, 



n\ nJ 



and so on. 



LVII. On Ortho- and Meta-silicates. By William Odlino, 

 M.B., F.R.S., Secretary to the Chemical Society^. 



THE experiments of Colonel P. Yorke on silicaf, whereby 

 from its action on each alkaline carbonate a different 

 atomic weight was to be inferred, seemed at first sight highly 

 anomalous aiid unsatisfactory. But I believe that, u])on consi- 

 deration, his results will prove to be perfectly consistent, to 

 throw considerable light on the nature of the silicates, and to 

 indicate the simple relations of these salts to the pliosphates and 

 to polybasic salts in general. We are acquainted with various 

 binary compounds of hydrogen^ and with certain quadroxy-acids 

 and salts, indirectly procurable from them J. Thus, — 



Chlorhydric acid. H CI. II CIO'' Perchloric acid. 

 Sulphydric acid . H^ S. H^ S 0^ Sulphuric acid. 

 Phosphamine . 11^ P. H^ P 0^ Phosphoric acid. 



And it seems to be a general rule that binary hydrides with one, 

 two, three, or more atoms of hydrogen, yield quadroxy-acids and 

 salts, with an equal number of atoms of hydrogen, or equivalents 

 of basic metal respectively. 



But it is observable that if from ])hosphoric acid, H^ PO'*, we 

 abstract an atom of water, H^ 0, we obtain a new acid, the meta- 

 phosphoric, which corresponds to a distinct class of salts, the 

 metaphosphates ; while intermediate between common or ortho- 

 phosphates and metaphosphates we have several varieties of 

 compounds, among which the best- defined are the pyrophos- 

 phates, salts which result from the union of an atom of ortho- 

 phosphate with an atom of metaphosphate, thus : — 

 M^ PO'' + i\lP03 = M"* Y' 0' . 

 Now when phosphoric anhydride is fused with the salt of a 

 * Comnumicateil by the Author, 

 t Phil. Trans. 1857, p- b'63. 

 X 0=16, S=32, C=12, Si=28. 



