264 : REPORT—1885. 
be said here for both systems ; and, as the diversity of practice does not lead — 
to confusion, and consequently does but little harm (beyond in each case 
offending the ears of those accustomed to the opposite system), the ques- 
tion need not be regarded asa vital one. Objections which have been — 
urged against the use of any termination in such cases are that chemists — 
have not always been able to agree as to which termination is to be used — 
in a given case, and that, apart from this, the practice causes beginners — 
erroneously to surmise the existence of a second series of salts. The — 
objection on the other side is that the omission of the terminal ‘ic’ breaks 
the uniformity of the system and leads beginners to suppose that barium — 
sulphate, for instance, has a different constitution from cupric sulphate, 
In the case of carbon compounds, on the other hand, there is a distinct — 
advantage in affixing ic to the names of the positive radicals in ethereal 
salts. A neglect of this precaution leads to ambiguity—at all events in — 
the spoken name. Thus, though there is no ambiguity in the name ethyl 
phenylacetate when written, yet the ear cannot distinguish between it and — 
ethylphenyl acetate. This ambiguity is obviated by the use of the termi- 
nation ic: thus, ethylic phenylacetate and ethylphenylic acetate. 
In the use of the terminations ous and ic to distinguish different series — 
of acids and acid-forming oxides, the practice of chemists has also been 
very uniform. Indeed, with the exception of one or two isolated cases 
almost perfect unanimity has prevailed. 
To sum up, the ous and ic terminations when employed for purposes — 
of distinction in cases where two series of oxides, acids, salts, &e., are — 
known, have been almost free from ambiguity, and for this reason — 
deserve to be retained. On the other hand, in cases where only one series — 
is known, those chemists who have employed one or other of these : 
terminations have occasionally differed as to which ought to be used: 
the difficulty may be solved, as it has been done by some chemists, by 
avoiding the use of any termination in such cases. 5 
In complex cases where the above modes of naming prove inadequate, — 
recourse may be had to numeral designations. These appear especially — 
admissible in cases where an oxide occurs which is intermediate between — 
the ous and ic stage, and at the same time cannot be classed as a com- 
pound of oxides already classified and named. ; 
In applying numeral designations, it is most important to select only 
such as are free from hypothesis and which afford correct information, — 
In this respect, chemists appear of late years not to have been sufficiently — 
careful. As an example, arsenious oxide may be quoted; this compound 
is frequently termed ‘arsenic trioxide,’ the formula being written As.O3, _ 
and it is tacitly assumed that the molecule contains three oxygen atoms. 
There are three objections to this name :—(1) That, assuming the formula 
on which it is based to be correct, it affords no information as to the 
number of arsenic atoms associated with the three oxygen atoms; (2) © 
that it involves the assumption that arsenious oxide does not vary in 
molecular weight, whatever its physical state; and (3) that the formula 
of gaseous arsenious oxide is As,Oxg. 
In employing numeral designations to indicate molecular composi-_ 
tion in cases where this is established, it is therefore important to express” 
the number of atoms of each constituent element, as dicarbon heaachloride, 
C, Cl,. But in the case of solid and liquid bodies of which the molecular 
weight is either unknown or may vary with temperature, the name 
should indicate merely the relative proportions in which the constituents 
-are associated ; or, more explicitly, the name should indicate the propor-— 
