Dr. Odling on Ortho- and Meta-siiicates. 373 



Bi"'x\0'' . H^ (Becker) Seuucrystalluie, silky, soluble. 

 Pb2 HNC (Pelouze) Soluble crystalline salt. 



Pb^NO'' (Berzelius) Sparingly soluble. 



Hg3 NO'' (Kane) Insoluble salt. 



(Hgg)^ UNO* (Kane) Crystalline yellow salt. 



(Hg2)^HN0'' (Gerhardt) Large oblique rhombic j)risms, 



almost colourless, soluble in water. 

 Formula disputed. 

 Moreover, precisely as there are intermediate quadribasic 

 phosphates, or pyrophosphates, with seven atoms of oxygen, so 

 ought there to be intermediate quadribasic nitrates with seven 

 atoms of oxygen ; and we have, at any rate, one marked example 

 of this class of salts, in the ethyl-nitrate of mercuiy, Hg^ Et N^ 0'^, 

 analogous to sodio-pyrophosphate of copper, Cu^ Na P^ 0'^, and 

 to double pyrophosphates in general. To this class may also be 

 referred two soluble crystalline mercurous and mercuric salts 

 having the respective formulae (Hgg)^ HN'^ 0'' (Gerhardt) and 

 Hg4 N2 07 . 2H2 (Mitscherlich). 



The most highly basic class of carbon salts that we usually 

 admit are the carbonates, M^ CO^ bibasic salts analogous to the 

 sulphites, M^ SO^, precisely as the most highly basic niti'ogen 

 salts that we usually admit are the nitrates, MNO^, monobasic 

 salts analogous to the chlorates, AICIO^. But precisely as we 

 obtain an orthonitrate, M^ NO'*, analogous to a normal phos- 

 phate, by adding an atom of protoxide to a nitrate, so do we 

 obtain an orthocarbonate, M'' CO'*, analogous to a normal sili- 

 cate, by adding an atom of protoxide to a carbonate. We are 

 acquainted with a considerable number of well-defined ortho- 

 carbonates, constituting, in fact, the class of salts usually known 

 as dicarbonates, of which the following are examples : — 



Ca"* CO^ Bicarbonate of calcium. Half-burnt lime. 



Ca'*CO''. H'^ Hydrated dicarbonate of calcium. Disinte- 

 grated lime. 

 Zn' CO"* . 211- O Hydrated dicarbonate of zinc. (Schindler.) 

 Pb"* CO"* . H^ Hydrated dicarbonate of lead. Crystalline. 



(Yorke, Bonsdorflf.) 

 Cu** CO'* . Dicarbonate of copper. Mysorine. 



Cu^CO". H'^0 Malachite. Crystalline? 

 Possibly also certain hydrated salts may belong to this class. 

 Thus the carbonate of sodium that results from the exposure of 

 the crystallized salt to the air, may be either a hydro-dicar- 

 bouate, H^ Na^ CO*, or a hydrated carbonate, Na^ CO^ . 11^ 0, 

 &c. 



AVe arc acquainted likewise with a few carbonates, known as 

 scsquibasic carbonates^ containing seven atoms of oxygen, and 



