ON THE THEORY OF TYPES IN CHEMISTRY. 127 
heated with a third equivaleut of water yield, in like manner, two 
of tribasic phosphoric acid; 2 (PH,O,) = (PH,O,),0, + H,O, 
=e, O,0)0, = 2.PH,0,. 
Gerhardt long since maintained that we cannot distinguish between 
polybasic salts and what are called sub-salts, which are as truly neu- 
tral salts of a particular type. Thus the bibasic and tribasic phos- 
phates are to be looked upon as subsalts, which sustain the same 
relation to the monobasic phosphates that the basic nitrates bear to 
the neutral nitrates. He succeeded in preparing two crystalline sub- 
nitrates of lead and copper, having the formulas NO,,M,O,,HO 
(tribasic), and NO,,M,0,,H,O, (quadri or heptabasic), both of 
which retain their water of composition at 392? F. The compounds 
of sulphuric acid are: Ist. The true monobasic sulphate S,O,MO, 
corresponding to the Nordhausen acid and the anhydrous bisulphates ; 
2nd. The ordinary neutral sulphates, S,0,, M,O,; 3rd. The so- 
called disulphates, S,0,, M,O,, corresponding to the glacial acid 
density 1-780; 4th. The type, S,0,, M,O,, represented by turpeth 
mineral; and, 5th. The so-called quadribasic sulphates, S,O,M,0O,. 
The copper salt of this type, according to Gerhardt, retains, moreover, 
6HO at 392° F.—(Gerhardt on Salts, Jour. de Pharmacie, 1848, 
vol. xii.; Am. Jour. Sci. vi. 337.) 
Without counting the still more basic sulphates of zinc and copper, 
described by Kane and Schindler, we have the following salts, which 
in accordance with Wurtz’s notation, correspond to the annexed 
radicals : 
1. Monobasic ............ S,HO, =S,0O, monatomic. 
PRMURTIG 1 danse nasienscas  SgtlaQg 550,04, diatomic. 
3. Quadribasic............ S,H,0,,=S,0, tetratomic. 
A. Sexbasic........+..,..-.. S,H,O,,=S, ,. hexatomic. 
5. Octobasic............... S,H,O,,=S, —O, octatomic. 
It is easy to apply a similar reductio ad absurdum to the radical 
theory in the case of the oxychlorids and other basic salts, and to 
show that the radicals of the dualists are often merely algebraic ex- 
pressions.—(See further my remarks in the Am. Jour. Science, vil. 
402—4.04..)* 
a a lila RAs ea te SINT A ae Ee ae ee 
* Those who are familiar with chemical literature, will remember an amusing jew d’esprit 
of Laurent’s, in which he invited the attention of the advocates of the radical theory to a 
newly invented electro-negative radical Hurhizene.—Comptes Rendus des Travaux de 
Chimie for 1850, pp. 251 and 376.) We observe a late writer in the Chemical News (vol. i. 
p.826) proposing, as a new electro-negative radical, under the name Of hydrine, the peroxyd 
of hydrogen HOz, the eurhizene of Laurent! 
