166 ARRANGEMENT OF THE ELEMENTS IN COMPOUNDS. 



and three atoms of hydrogen or metal. The three phosphates 

 of water and the corresponding phosphatoxides of hydrogen 

 would be represented as follows : 



HO + PO 5 . 2HO + PO 5 . 3HO + PO 5 

 H + PO 6 . 2H-fPO 7 . 3H + PO 8 



Such radicals and such compounds with hydrogen startle us 

 from their novelty, but it may be questioned whether they are 

 really more singular than the anormal classes of phosphates, 

 containing several atoms of base, for which they are substi- 

 tuted, but which we have been more accustomed to contem- 

 plate. All the salt-radicals known in a separate state, such as 

 chlorine and cyanogen, combine with one atom only of hydro- 

 gen or metal, but it would be unfair to assume in the present 

 imperfect state of our knowledge that other radicals may not 

 exist, capable of combining with two or three atoms of metal, 

 as the phosphate radicals are supposed to do. The existence of 

 at least one such radical is highly probable, as will afterwards 

 appear. 



In conclusion, it may be stated that neither view of the con- 

 stitution of the oxygen-acid salts, (which are alone affected by 

 this discussion), rests on demonstrative evidence they are 

 both hypotheses and are both capable of explaining all the 

 phenomena of the salts. But to whichever of them we give a 

 preference, we can scarcely avoid using the language of the 

 old theory in the present state of chemical science. 



Without deciding definitively in favour of one or other 

 of these views, a distribution of the great class of salts into 

 three orders may be made. A certain number of salts con- 

 tain radicals which can be isolated, others oxygen-acids 

 which can be isolated, while others have yet afforded neither 

 radical nor acid in a separate state. Hence, there are : 



1 . Salts of isolable radicals : chlorides, cyanides, sulpho- 

 cyanides, &c. 



2. Salts of isolable acids : sulphates, carbonates, &c. 



3. Salts which contain neither an isolable radical nor an 

 isolable acid: nitrates, acetates, hyposulphites, &c. Even 

 admitting that all salts have the same constitution, the 

 capability of breaking up in such different ways must affect 

 their modes of decomposition in different circumstances, and 

 produce distinctions in properties which would render such a 

 division of them expedient. 



