Marcu 15, 1912] 
copper group, the complete precipitation 
of lead and cadmium as sulphides. 
It is so much a matter of common knowl- 
edge that the chemical changes upon 
which analytical procedures rest are far 
better understood, and therefore con- 
trolled, because of the fruitful hypothesis 
of Arrhenius, that no extended statement 
of this seems necessary in this connection. 
Jt may, however, be wise to point out that 
there is a certain tendency to assume that 
this theory and its applications constitute 
“‘physical chemistry’’ and that there is 
reason for complacency when one has ac- 
quired a fair understanding of these 
points. While the foregoing statements are 
far from complete with respect to those 
points at which our modern chemistry and 
physics touch analytical chemistry, it must 
be evident that the possibilities for assist- 
ance are far wider and, indeed, more im- 
portant than a mere ionic interpretation 
of chemical changes. For it must be ad- 
mitted that our knowledge of ionic changes, 
even in a qualitative sense, is still inexact 
with reference to many reactions familiar 
to the analyst, and that the most useful 
data are those of a quantitative character, 
to obtain which we must command a 
knowledge of the wider field of physical 
chemistry in a broad sense. 
Modern investigation has then, especial- 
ly in the border land between physics and 
chemistry, given us new tools for our trade 
as chemical analysts. But it has done still 
more for us by showing us what it means 
to use them, and it is here that, as analysts, 
we should learn our lesson. It is, I think, 
fair to say that the one fundamental rea- 
son why much of the published work of 
individuals or commissions fails of effec- 
tiveness and permanence and, in part, the 
reason for the lack of respect in which the 
chemical analyst and his work are held, is 
the lack of appreciation on the part of 
SCIENCE 
401 
authors of the one-sidedness of the pub- 
lished results, and of the procedures 
adopted as adequate or as the best obtain- 
able. The pages of our journals are, un- 
fortunately, too largely occupied by de- 
scriptions of processes, which are supported 
by data obtained under but one set of con- 
ditions, and applied at most to one or two 
sorts of materials. These conditions are 
empirically established and are, in many 
cases, not such as could be controlled under 
the necessary routine of analysis of ma- 
terials of more complex structure. The 
tests, upon which efficiency is claimed, have 
often been made with pure materials, and 
in solutions, the contents of which could 
be easily adjusted and determined, con- 
trasting in this respect with customary 
analytical conditions. Many authors of 
analytical procedures lose sight of the im- 
portant fact that the success of these pro- 
cedures, in their own hands, has usually 
been attained only at the cost of consider- 
able practise and as the result of the ob- 
servance of a series of, often, apparently 
minor modifications, which they more or 
less unconsciously ignore when they de- 
scribe the process for publication. It is 
exactly this really inexcusable ignoring of 
these conditions, on the one hand, and the 
even more frequent failure to study their 
influence systematically, on the other hand, 
which has condemned much of the pub- 
lished material. It is true that the intelli- 
gent author is between two fires—on the 
one hand his desire to help his colleagues, 
on the other hand, the board of editors 
who, in these days of many papers, must 
insist upon reasonable brevity. As one 
who has seen many manuscrips in this 
field, may I suggest, especially to the 
younger authors, that I am sure that, while 
the editors must insist on the omission, for 
example, of statements to the effect that it 
is inadvisable to remove a stirring rod 
