366 Royal Society. 



being tribasic, is expressed empirically by the formula PO4 H3. The 

 labours of Messrs. Laurent and Gerhardt greatly contributed to the 

 establishment of these results, which are uncontroverted. 



We have hitherto been accustomed to resort very freely to ima- 

 ginary distinctions of form and arrangement of matter to explain the 

 differences of properties ; but of late years an opposite tendency has 

 arisen, and chemists have felt the necessity of reducing their language 

 and ideas to simpler and more consistent forms. This necessity was 

 first felt in the most complex, /. e. the so-called organic part of che- 

 mistiy. But the simplifications thus introduced have proved to be 

 equally applicable to the inorganic part of the science ; and their 

 introduction is calculated to disengage, for the consideration of sub- 

 stantial differences of composition, the attention which has hitherto 

 been absorbed by imaginary distinctions of form. Being unable to 

 express the constitution of compounds M'ithout some formal artifice, 

 we shall be able to see and compare their substantial differences 

 most easily when all unnecessary variations of those formal artifices 

 are eliminated. The success of this operation of course depends on 

 our finding one form sufficiently general to replace the special and 

 limited forms now employed. 



In some papers published in the Journal of the Chemical Society 

 two or three years ago, I endeavoured to show that the constitution 

 of salts may he reduced to the type of water ; that acids and bases 

 being, truly, acid salts and basic salts, are perfectly conformable to 

 the same principle ; and that, amongst other things, the difference 

 between monobasic and bibasic acids, &c. admits of a simple and easy 

 explanation by it. The leading propositions in those papers have been 

 adopted by several eminent chemists in this country and in France ; 

 and M. Gerhardt speedily enriched science with a series of brilliant 

 and striking illustrations of their truth. As regards the constitution 

 of bibasic acids, M. Gerhardt's results were, however, at variance 

 with that theory ; and he was led to represent them by formulae 

 equally inconsistent with his own previous views on the subject, I 

 believe that this discrepancy is satisfactorily removed by the facts I 

 have the honour of submitting to the consideration of the Society. 



An atom of nitric acid, being eminently monobasic, is, as we have 



pi 

 already shown, represented in the monobasic type yjO by the 



formula ^ HO, in which peroxide of nitrogen (NO^) replaces one 



j^O) is ob- 

 tained by replacing one atom of hydrogen in the type by its equiva- 

 lent of potassium; and nitrate of potash ^ k^J ^J ^ simultane- 

 ous substitution of one atom of hydrogen by peroxide of nitrogen, 

 the other by potassium. Sulphuric acid is formed from two atoms of 



H 



■water „ ; one of hydrogen from each is removed, and the two 



H 



