8 
ON RECENT CHANGES IN 
The formulae in the last column evidently remind us of one circumstance 
only ; namely, that the hydrogen written first is replaceable by metals to the 
extent of one, two, or three atoms; those containing one replaceable atom 
beiug denominated monobasic, those with two, dibasic, and those with three, 
tribasie acids. Similarly with saline compounds, the ordinary formula tells 
us only the proportion of metal in the molecule. 
Formula. 
Nitrate of Potassium . . . . 
Carbonate of Potassium . . . 
Acid Carbonate of Potassium 
Ordinary Phosphate of Sodium . 
Sulphate of Copper . . . . 
Mercuric Nitrate,. 
Ferrous Sulphate. 
Ferric Sulphate. 
etc. 
Old. New. 
KO, NO. . . EN0 3 
KO,CO, . . K 2 C0 3 
KO, HO,2C0 2 KECO 3 
2NaO,HO,PO s Na 2 HPO 
CuO, S0 3 . . CuS0 4 
Hg0 2 , 2IN Or . Hg21S Oo 
FeO,S0 3 . . FeS0 4 
Fe 2 0 3 ,3S0 3 . Fe 2 3S0 4 
etc. etc. 
But, referring still to the acids as example, there are other chauges of 
which they are capable, and which it is sometimes necessary to indicate in the 
building up of their formulae. 
} ° 2 ( 
or S Oc 
(HO 
IRQ 
or SO.2 
ho) 
In representing sulphuric acid as SO. 
H 2 
we suggest much more than by the simpler expression H 2 S0 4 . By formulae 
such as these, in fact, we recall the principal reactions in which sulphuric 
acid takes origin, or in which it permits the substitution of one or other of its 
constituent parts. 
Hydroxyl (Peroxide 
of Hydrogen). 
(HO ) 2 
Sulphurous Acid Gas. 
SO. + 
It 
Sulphuric Acid. 
(S0 2 )"2H0 
Sulphurous Acid Gas. 
SO. 
(S0 2 )"C1 2 
+ 
Chlorine. 
+ ci 2 
2 Mols. of Water. 
H}o _ 
Chloride of Sulplxuryl. 
(SO,)" Cl 2 
H 
(S0 2 )" 
H 
Sulphuric Acid. 
(8 °£}o. 
1 
O 
O 
+ 
H 
H 
] 
CL 
Hydrochloric Acid. 
+ 2HC1 
Here it appears that the chlorine of the chloride of sulphuryl seizes on an 
atom of hydrogen from each molecule of water, whilst the S 0 2 retaining its 
bivalent character locks the two residues together, as it had previously done 
the two atoms of chlorine. The formula of the chloride is thus quite com¬ 
parable to that of the hydrate. 
(*<{S M"{%°o 
On inspecting these two compounds it becomes immediately evident that 
there should be one intermediate between them partaking of 
the characters of both. This body has in reality been produced. 
W hilst rendering manifest possible changes of this kind, these formulae 
allow ^ the expression ot ordinary decompositions with every convenience. 
The following examples of the sulphates show how the constitution of salts 
of the metals is represented on the same plan:— 
