ON CHEMICAL NOMENCLATURE. 265 
tion of the radical associated with what may be termed the characteristic 
element of the compound. No difficulty occurs in the case of the chlorides, 
or analogous compounds with the monad elements generally, these being 
termed mono-, di-, tri-, tetra-, penta-, or hexa-chloride, &c., according as 
combination is in the proportion of 1, 2, 3, 4, 5, or 6 atoms of chlorine to 
latom of the characteristic element. The application of this system 
would involve the use of the names tin dichloride and iron trichloride 
(not sesqui-chloride) for stannous and ferric chlorides respectively, names 
which accurately express the relative proportions of chlorine to metal in 
these compounds without any hypothesis as to their molecular composition 
—a composition, which in the case of the former compound, at all events, 
certainly depends on temperature. It will, however, involve a slight depar- 
ture from the existing practice when applied to oxides, sulphides, and other 
J 
compounds of polyad elements; thus oxides of the type (R,.)’’O would 
be termed hemv-oxides, since they consist of the characteristic element 
and oxygen in the proportion of one atom of the former to half an atom 
of the latter. Oxides of the type (R,)“O; would be termed sesqui- 
oxides, since the characteristic element and oxygen are present in the 
proportion of one of the former to one and a half of the latter. Oxides of 
the type R. O; would be termed sesterti-oxides, as they contain oxygen 
and the characteristic element in the proportion of two and a half 
atoms of the former to one of the latter. Oxides of the types RO, 
RO,, RO;, and RO,, would be termed respectively mono-, di-, tri-, and 
: tetr-oxides. 
Acip SAtts. 
‘ There are two distinct classes of salts to which this name has been 
given :— 
1. Salts with two or more metals, one of the metals being hydrogen. 
2. Salts formed from these by the removal of water. 
Until comparatively lately, no attempt was made to give distinctive 
names to these two classes, except that sometimes the words hydratic and 
anhydrous were used to distinguish them. The distinctive names— 
pyrophosphate, metaphosphate—which Graham gave to the two sets of 
anhydrous acid phosphates were founded on the supposition that the 
phosphoric acid (PO;) existed in them in two modifications, different 
_ from the acid of the ordinary phosphates. 
_The nomenclature used by nearly all chemists from the beginning of 
this century until about 1860 is illustrated on tables 3-6. Acid salts in 
_ which for the same quantity of base there is 2,3, . . . &c. times as much 
acid as there is in the normal salt are called bi ate, ter ate, &c. (in 
German, doppelt (or zweifach) saures Salz, dreifach saures Salz, 
&e.) In English and French the Latin adverbial numerals bis or bi, ter, 
- &. seem always to have been used until about twenty years ago, when 
Greek adverbial numerals were introduced for the anhydrous acid salts. 
Watts’s: Dictionary and Naquet are the first English and French 
authorities in which we have observed this change. 
Basic Sats. 
’ There are two distinct classes of salts to which this name has been 
given :-— 
1. Salts with two or more salt radicals, one of the salt radicals being 
hydroxyl. 
2. Salts formed from these by the removal of water. 
