the hydrogen is combined with either oxygen or the aqueous radicle, 

 Oil : water will then he 11<>H, and alkalies or basic hydrates, MOIL 

 The group ()H. or the <-HJU.''<>/IS rftdiclt^ otherwise called Jti/dro.vyl, may 

 be looked on as a haloid like the chlorine in table salt, not only because 

 the element ( '1 and the group OH very often change places, and com- 

 bine with one and the same element, but also because free chlorine is 

 very similar in many respects and reactions to peroxide of hydrogen, 

 which is the same in composition as the aqueous radicle, as we shall after- 

 wards see. Alkalis and basic hydrates are also salts consisting of a 

 metal and hydroxyl for instance, caustic soda, XaOH ; this is therefore 

 termed sodium Jiydroride. According to this view, nc.'nl xa/f* arc 1 those 

 in which a portion only of the hydrogen is replaced bv a metal, and a 

 portion of the hydrogen of the acid remains. Thus sulphuric (H.,SO, | 

 acid with sodium not only gives the normal salt Xa^SO,. hut also an 

 acid salt, XallSO,. A //r/x/r wilt is one in which the metal is com- 

 bined not only with the haloids of acids, but also wit h the aqueous radicle 

 of basic hydrates -for example, bismuth gives not only a normal salt 

 of nitric acid, .l>i(X"( ) :i ) s , but also basic salts like I>i(< >H ) L) (XO.<). As 

 basic and acid salts corresponding with the oxygen acids contain 

 hydrogen and oxygen, they are therefore able to part with these as 

 water and to give anhydro-salts, which it is evident will be equal to 

 compounds of normal salts with anhydrides of the acids or with bases. 

 Thus the above-mentioned acid sodium sulphate corresponds with 

 the anhydro-salt, Xa._,S._,O 7 , equal to L'XallSO,, less H 2 O. The loss 

 of water is here, and frequently in other cases, brought about bv 

 heat alone, and therefore such salts are frequently termed />yro-saffts 

 for instance, the preceding is sodium pyrosulphate (Xa.jS.^O-), or it may 

 be regarded as the normal salt X"a._,SO } -(- sulphuric anhydride, SO V 

 l)i,nl,Ii' salts are those which contain either two metals, 1\ A1(S( ),).,. or 

 two haloids/' 7 



' The abo\e-enunciated generalisation of the conception of sa It s as compound- of 

 the metal- (simple, or compound like ammonium. N 1 1 , i, wit h the haloids i simple, like 

 impound, like cyanogen, CN. or the radicle of sulphuric acid, SO,), capable 



