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THE PHARMACEUTICAL JOURNAL AND TRANSACTIONS. [September 28, 1872. 
mirably supply this want, so far as regards the elements 
of chemistxy and physics. We are glad to observe 
further that Mr. Huxley is engaged on a similar 
primer, introductory to the study of natural science. 
The series is published at a wonderfully cheap price, 
a shilling each ; the type is excellent, the cuts are nu¬ 
merous and useful, and the binding seems to be strong. 
The fact that the authors are such men as Professors 
Roscoe and Balfour Stewart is a sufficient guarantee 
that they have been carefully compiled and thoughtfully 
adapted for the purpose intended. 
We are glad to notice that in the chemistry primer, 
Professor Iioscoe has departed from the unphilosophical 
method of beginning with a study of the elements. To 
start, as is usual, with oxygen or hydrogen, per¬ 
plexes a child with something totally new to him, 
which he cannot, therefore, connect with his previous 
knowledge ; and, further, in dealing with an element as 
distinguished from a compound, it introduces the con¬ 
ception of an abstract idea, of which a child is in¬ 
capable. With great wisdom Professor Roscoe begins 
as follows :—“ Here are four things which we all know 
well—fire, air, water, earth,—let us try to learn what 
science teaches us about them then the author goes on 
to explain that we come to know about these things by 
handling or examining them, and that we call this 
examination experiment, describing what kind of expe¬ 
riments properly belong to the study of chemistry. The 
following headings to the sections under the first divi¬ 
sion, fire, will show how the book proceeds. “ What 
happens when a candle or a taper burns ?” “Besides 
carbonic acid gas, there is another substance formed when 
the candle burns, viz., water;” “When a candle is 
burnt, nothing is lost;” “Heat is felt when chemical 
union goes on.” In the next division we are told 
about the air : “ What the air contains;” “ What 
goes on when we breathe air?” “What sort of 
action have plants on the air ?” and so on. At the 
end of each division the lesson is summed up under 
the head of “ What we have learnt.” After dealing 
with the elements of the ancients and broadly explaining 
their nature in the light of the present day, the author 
leads the learner up to the elements that modern science 
has revealed. The properties of the principal elemen¬ 
tary bodies are then described, and the book ends with 
an explanation of the meaning of combining proportions 
and chemical equations, so lucid as to be quite within 
the comprehension of the average boy. We remark in 
passing a little inaccuracy that called forth a letter in 
the pages of a contemporary. On page 26 hydrogen is 
said to burn with a pale blue flame. Mr. Barrett has 
shown that a flame of pure hydrogen, of any tint, is 
slightly brown; the blueness so commonly noted being 
due to the presence of sulphur, usually derived from the 
decomposition of the spray from the sulphuric acid 
employed in generating it; the presence of carbonic 
acid in the breath of the operator, or in the air of the 
room, also often leads to a deceptive appearance of the 
flame. 
The primer by Professor Balfour Stewart on physics 
follows the same general scheme as the chemistry pri¬ 
mer. It is, perhaps, not quite equal to its predecessor, 
but then Professor Roscoe has had the advantage of 
many years’ experience in teaching both young and old 
boys, and also the aid derived from noting the weak 
points in the host of elementary books on chemistry that 
have been published. Professor Stewart is the first to 
write in the English language a simple and sound pri¬ 
mer on physics, and we anticipate much good from its 
publication. The section on the “ Use of certain Forces,” 
p. 10, is capital, and will excite that wonderment and 
interest in a boy which urges him on to learn more. 
But the Author will allow us to make one or two sug¬ 
gestions that struck us on looking through his work. 
We think that occasionally the language or illustrations 
are a little too childish, young boys are apt to resent 
this more than many writers imagine. Again, we think 
it is a mistake to explain a thing too fully in a school¬ 
book ; if every difficulty is made laboriously clear in his 
text-book, a lad gets into a habit of reading without care, 
and expects to be pushed up every round in the ladder of 
knowledge. The business of a teacher is to help his 
pupil out of the difficulties he gets into, and stimulate 
him to fresh exertion. We rather expect a teacher will 
find some little difficulty in using this physic primer as 
a class-book ; we may be wrong, but we should be glad 
if the author could at some time make the experiment. 
Then in explaining the electrical machine, there is a 
serious but very common error, which will puzzle the 
learner, as the reverse statement is made in the next 
sentence. On p. 116, after describing the prime con¬ 
ductor of the electric machine and how it is armed with 
points, the Author goes on to say, “ Now you have 
already been told that points have a great tendency to 
draw off electricity. The consequence is, that these 
points draw off, or collect, the positive electricity of the 
glass and carry it to the conductor, where it remains, 
since the conductor stands upon glass supports.” This 
is incorrect. The points discharge on to the machine 
the negative electricity induced upon them by the posi¬ 
tive of the excited glass, and then the prime conductor 
remains positively electrified by its loss of negative. 
That the Author’s rendering is not put for the sake of 
simplicity is evident from the next sentence, where, in 
explanation of why we get a spark by putting our 
knuckle to the prime conductor 1 , we read, “ The reason 
is that the positive electricity of the conductor separates 
the two electricities which are together in my finger, 
driving away the positive, which is of the same kind as 
itself, to the earth through my feet, but, on the other 
hand, attracting the negative itself. The two electrici- 
tie 3 then rush together through the air and unite with 
each other, and in so doing they form a spark.” 
Even this latter paragraph is open to the objection 
that a lad gets an idea from such a statement that the 
two electricities are something substantial, always 
indulging in the bad habit of knocking up against 
each other and thereby splintering off sparks. Is any 
notion more common than that lightning is some sort of 
Greek fire poured out of a charged cloud, which relieved 
of its burden, furiously rushes to its neighbour and 
hitting it a terrific blow, makes the subsequent thunder. 
Now we think a child should be taught that when we 
see lightning we do not see electricity but only one of 
the results of that force, namel} 7 , air made to glow fear¬ 
fully hot along all the devious track of the discharge. 
Then he might be shown how gases can be made white 
hot, having previously learnt how platinum gets incan¬ 
descent, owing to the resistance it presents to the dis¬ 
charge. Another point in the primer we think capable 
of improvement is an enlargement of what is said on 
magnetism. The same objection exists in Professor 
Stewart's larger text-book on 4 Physics,’ where this sub¬ 
ject is treated in rather a meagre way ; here only two or 
three lines are devoted to it, and the fundamental law 
of magnetism is not even alluded to. There is, of course, 
much to be said about the impossibility of dwelling on 
everything in a primer, but every boy has seen a com¬ 
pass and ought to know something about it; and such 
instruction would not be forgotten from the law of the 
association of ideas. 
There can be no doubt that the essence of all effective 
teaching is to fasten each additional link in the chain of 
knowledge on to that which preceded it; thus by.rising 
from what is already familiar to that which is less 
familiar, the ^child, and the man too, gets a firm hold 
of facts and a just view of phenomena. It is because 
this method is followed so largely in these primers, ad¬ 
mirably so in the chemistry primer, that we believe 
they will be found a powerful means of diffusing elemen¬ 
tary scientific instruction. 
