G. F. Barker on normal and derived Acids. 389 
The above facts, we may remark in passing, throw much 
} light on the manner of writing rational formulas. In all ter- 
_ hary compounds properly so called, the positive and the nega- 
tive radicals are united by oxygen ; indeed, this is the defini- 
tion of an acid, a base and asalt. In all normal acids and 
their salts all the oxygen performs a linking function, thus :— 
Potassic ortho-sulphate. Baric ortho-sulphate. Aluminic ortho-sulphate. 
% & &@-0O o-—? At Al 
\/ ydticgl Lee heyy 
ey OA <7 8 
Ss 
watt tas 7s BS t. se eee.” 
oe 
eS eat 
But in the derived or meta-acids a part of the oxygen is united 
With the radical by both its bonds, and hence takes no part 
in binding the radicals together. * In all the mono-meta aci 
one atom of oxygen is thus united, in the di-meta acids two, 
etc. For example, 
Sodic Sodic : 
mono-meta-perchlorate. di-meta-perchlorate. cece A 
a oO oO 
} | 1 
Na0—Cl—ONa pam pt coo 
0. 
= ¢ &, 3 *b; 2 
This difference may be we by the acces rmulas, 
thus: ortho salts CI—OK, 8 fe B=(OK), etc.; meta, 
(PO )}=0, Bi” , (NO, )—OK, (Cl Oe es or re in 
the form of eee typical formulas K "10, Na, tO, K, to,, 
and oe O, NOs)" O, (C10) 00. Hence it appears 
desirable that de eed of the water type should be retained 
for rational formulas, since by it, this essential difference in the 
: me 
function of the oxygen may be readily indicated. S Cs 2)’ bo 
designates at once cesic di-meta-phosphate, or: bo, bis- 
muthic mono-meta nitrate, CoP ‘to, magnesic di-meta- 
: SO)” 
_ Sulphate, wee Lo , platinic mono-meta-sulphate, _ ‘f 0, 
* This direct roved by the fact that this oxygen may be replaced by 
8 radical of no perch i @ Pie monad chlorine, for example, without 
breaking up the molecule; while the oxygen which unites the radicals to each 
‘Other, cannot be so without decomposing the molecule. 
