Nov. 11, 1869] 
NATURE 
51 
obtain the required result, they either think that some- 
thing in nature has gone wrong, or that the author of 
the book is fibbing, and they are the last to imagine that 
they are themselves to blame; it is sufficient for them to 
have tried—or rather not tried—and they pass willingly 
to the next operation, most probably again to court defeat. 
To these the only cure is to act upon the advice, “ Do not 
hurry.” Another class of persons, to whom the second 
part of these “ Memoranda” specially applies, are those 
who confine all their powers to waiting ; thus they watch 
the slow filtration of a single gelatinous precipitate, and 
with a kind of dreary pleasure either dream away their 
time, or (more commonly) annoy their more diligent neigh- 
bours, thinking that nature is invariably slow to move, 
and that patience is the only virtue they need to cultivate. 
These must be made to learn that economy of time is a 
necessary part of the chemist’s duty, and that he, “in spite 
of the proverb, may do more than one thing at a time by 
allowing things to do themselves.” The chemist’s third 
commandment is fairly given as, ‘‘ Be economical of ma- 
terials.” Who that has seen beginners work does not 
value this recommendation? Many seem to think that 
the more they deluge the substances they have to examine, 
first with acids, and then with alkalies, the more likely 
are they to discover the philosopher’s stone, or to find 
their needle in the bottle of hay! How long some 
students take to find out that every molecule of acid or 
alkali, added above the required quantity, serves only 
as a blind to their reactions, and is in reality a most 
wilful adulteration of their material, with perhaps several 
thousand times its weight of dirt! “ Never begin an ex- 
periment,” says Mr. Madan, in his fourth article, “ until 
you have looked over all the preparations for it, to make 
sure that you have everything within reach ;” and we 
would make this advice apply not only to test-tubes and 
gas-jars, but to the mental preparation also. No experi- 
ment ought to be made until the student knows what he 
is going to do. He must either read a description of 
what he is to do, or he must see the experiment per- 
formed by his teacher; and, above all, he ought to be 
aware of the theoretical explanation of the changes he 
is about to witness. The writer for one does not think 
that laboratory instruction cannot be valuable, unless the 
student has already acquired a certain knowledge of the 
subject by attendance on lectures; but the theoretical 
instruction must then of necessity accompany the practical 
tuition. The very first experiment which the beginner 
may make—viz. that of heating oxide of mercury in a 
test-tube—must be the occasion for an explanation of the 
laws of definite combination by weight, for a statement of 
the numerical exactitude of all chemical change. Exer- 
cises must at once be given, and continue to be given, in 
illustration of these Jaws; and thus from the first the 
student must be made to grasp the facts of the exact 
nature of the science. He must be disabused at once of 
the notion of some who, when they enter the laboratory, 
“look upon chemistry as a mere amusement, as a means 
of getting up a few explosions, creating a few unsavoury 
smells, producing a few striking changes of colour.” Unless 
practical chemistry is taught with these aims, in a manner 
calculated to afford an exact mental discipline, it is worse 
than useless. If the student does not cultivate habits of 
attention, close observation, and patient inquiry, he can 
1 
gain nothing from laboratory work ; on the contrary, he 
becomes negligent and impatient, he does not care to look 
for what is going on, and instead of gaining immensely, as 
he ought, in habits of self-reliance, he loses all confidence, 
finds physical science a delusion and a snare, and returns 
(if he has any taste for learning at all) to the more con- 
genial path of literature. 
The volume in question will much aid those who teach 
with this view, and it will afford still more active help 
to those who, possessing no teacher, have to learn for 
themselves. 
The descriptions of the simpler operations of glass- 
working in the beginning of the volume, and of the con- 
struction of tube apparatus, are clearly given; and these 
pages are, of course, especially interesting to the self- 
educated student. The exercises on solution, precipitation, 
filtration, and distillation, are described with care, and the 
examples well chosen. It is very difficult to know how 
far such descriptions should go as regards details. The 
description of the manufacture of lime-water is as clear 
as that preparation ought to be. But is such detail 
needed where a word of explanation can be given? This 
shows the impossibility of writing a book on practical 
manipulation exactly fitted for all classes of students. 
In the second section, on preparation and examination 
of Gases, we miss the theoretical explanations which, as 
we have said, must accompany the practical and manipula- 
ting directions ; nor do questions, numerical or otherwise, 
accompany the exercises. This is to be regretted: a book 
especially written for those who work alone should contain 
a series of examples such as we find in many of the 
smaller manuals. With this exception this portion of the 
book is as good as need be, A chapter on the prepa- 
ration of Reagents in use in the laboratory is espe- 
cially valuable to the self-taught student. The solutions 
are made according to system ; and in the preparation 
the student is familiarised with the metrical system of 
weights and measures: whilst under each heading the 
tests for the purity of the reagent are given ; thus :— 
Barium Chloride (BaCl, in 20 c.c.). 
c.c. of water, and dilute to 100 c.c. 
The purity of the salt may be tested as follows. Place about 
5 c.c. of the solution in a test-tube, heat it nearly to boiling, and 
add a slight excess of dilute hydrogen sulphate. While the 
precipitate of barium sulphate is subsiding, get ready a filter (of 
Swedish paper), wash it two or three times with warm water, 
then filter off the barium sulphate and evaporate the filtrate to 
dryness on a clean watch-glass. No solid residue should 
be left. 
Dissolye 12'2 grms in 80 
The authors, in their introduction to Qualitative 
Analysis, commence with the study of the acid radicles 
instead of the metals. This is, perhaps, the more scientific 
order of procedure than that beginning with the reactions 
of the metals ; but we must take leave to doubt whether it 
is so simple, or so likely to conduce to the clear under- 
standing of the reactions as the other older and more 
usually employed method. 
The nomenclature used throughout the work possesses 
one amongst many advantages over the others (unfortu- 
nately too numerous) now in use, in that it is identical 
with that now employed in Germany. Surely it is a 
matter of some importance to assimilate as much as 
possible scientific nomenclature in all languages. 
H. E. ROSCOE 
