90 
far more important object than to make chem- 
istry easy is to make it scientific. The ob- 
ject of the teacher should be to make the sub- 
ject clear, but I have not very much respect 
for making things easy, since in science what- 
ever is easy is swperficial. There is no inher- 
ent reason why we should make elementary 
chemistry appreciably easier for the average 
student than elementary physics; that is to 
say, make it more superficial. 
The argument against introducing the 
newer generalizations into the elementary 
teaching of chemistry, based upon the fact 
that their omission renders the subject easier, 
is, then, in reality a strong argument in favor 
of incorporating them. 
The question as to whether it is easier for 
the teacher to introduce or omit the newer 
conceptions does not enter into the present 
discussion, since every efficient teacher is 
abreast with the development of his science; 
and furthermore, in matters of teaching, it is 
only the best good of the student that is to be 
considered. 
Let us now turn to the other question: 
What is gained by teaching elementary chem- 
istry from the standpoint of the newer gener- 
alizations ? 
A beginner in chemistry soon learns that 
when a chloride is treated with concentrated 
sulphurie acid, hydrochloric acid gas escapes, 
and the chloride is transformed into the cor- 
responding sulphate. At one time this was 
explained as due to the greater strength of 
sulphuric acid; but we can not offer this ex- 
planation any longer, since we now know that 
sulphuric acid is only a little more than half 
as strong as hydrochloric. 
The same beginner quickly learns that when 
a solution of a chloride is treated with a so- 
lution of silver nitrate, insoluble 
chloride is precipitated. 
These two classes of phenomena are typical 
of a large number of chemical reactions. In 
the past such facts were summarized by say- 
ing that whenever a gas can be formed it is 
formed, and whenever a solid can be formed it 
is formed. This was simply renaming the phe- 
nomena in question, but of course explained 
silver 
SCIENCE 
[N.S. Vou. XXXV. No. 890 
nothing. Yet it was the best that could be 
done at that time. 
It is a very simple matter to give any one, 
and therefore a beginner in chemistry, some 
qualitative conception of the effect of mass 
or quantity on chemical reactions—chemical 
reactions being dependent upon two things, 
the nature of the substances brought together, 
and their relative quantities. If the beginner 
can grasp one of these conceptions he can 
grasp the other. 
Given the conception of mass and even 
qualitatively its function in chemistry, the 
two typical reactions mentioned above can be 
interpreted or, indeed, explained. 
Hydrocloric acid having a low boiling 
point is a gas at ordinary temperatures, and 
escapes from the field of action almost as 
rapidly as it is formed; its active mass being 
thus reduced nearly to zero. 
The silver chloride formed is nearly insol- 
uble in water. It is precipitated as a solid 
and its active mass is thus small. I think 
this treatment renders the two typical reac- 
tions more clearly understood, and is more 
scientific than simply renaming the phe- 
nomena. 
I venture to predict that not a few students 
of chemistry, not only of one year’s standing 
but of several, are without any adequate con- 
ception of the importance of that condition 
in which matter in a given state of aggrega- 
tion is, when mixed with matter in the same 
or a different state of aggregation—in a 
word, of the importance of solution. 
If they were told that the whole science of 
chemistry is a branch of the science of solu- 
tions, they would either not understand the 
statement at all, or would regard it as a gross 
exaggeration. 
It is a simple matter to make this reason- 
ably clear, at least towards the end of the first 
year’s work in chemistry. By that time 
enough reactions have been studied to show 
the student that practically all, if not all 
chemical reactions take place in solution, 
using the term solution in the broad sense in 
which it is employed to-day. Matter in the 
pure homogeneous condition is scarcely 
