NATURE 
- ful, and the good remain unshaken ; they have been all 
the more firmly established, for they have been deduced 
from the order of the universe and from the mind of man 
himself. And that the pursuit of natural science does 
not lead to materialism, and in no way injures the ideal 
mind, is vouched for by the case of Alexander von Hum- 
boldt himself, who, even in extreme old age, kept up his 
love for research and power of work as well as his lively 
susceptibility for and energetic share in all the nobie 
pursuits of mankind. 
Dr. Cohn concludes his lecture, so brimful of true 
eloquence founded on sober fact, with a high com- 
pliment to the many worthy qualities of the Pre- 
sident of the Silesian Society, Dr. Goeppert. Such a 
man as he is said to be, the lecturer truly says, 
may hope, like Goethe, Humboldt, and other previous 
philosophers, to miintain to the utmost limit of existence, 
life, heart, and spirit full of the freshness of youth, and, 
moreover, in later generations be honoured as a true 
guardian of the highest good of grateful mankind, 
VALENTIN’S CHEMISTRY 
Introduction to Inorganic Chemistry. By W.G. Valentin, 
F.C.S. (London: J. and A. Churchill.) 
E must congratulate the author on the appearance 
of this volume. It is in reality a second and 
much improved edition of the first part of “ Valentin’s 
Introduction to Qualitative Analysis,” and it is very 
encouraging that a second edition is so soon wanted. 
This book is one of a class which for the sake of English 
science we could wish were more numerous. It teaches 
chemistry entirely by practical work, and at the same time 
gives the student a clear knowledge of the general prin- 
ciples of the science. The very first words, indeed, afford 
a good idea of the system pursued throughout the work. 
Experiment 1.—“Fill a glass cylinder or a test-tube with 
water, and invert it over a basin containing water, &c.” 
This experiment is the collection of hydrogen evolved 
from the action of sodium on water. This quota- 
tion may be taken as almost typical of the book. 
The methods of preparation and the properties of 
the various elements and simple compounds are 
studied by means of very carefully described and 
well-chosen experiments, and from his experiments the 
student is taught to draw deductions and generalisations. 
In this way the fundamental laws of chemistry are 
deduced from experimental facts, and a sound foundation 
of chemical knowledge is obtained. This method scarcely 
requires any recommendation ; the fact that the author 
has adopted it after a long experience of practical teach- 
ing in one of our largest laboratories is one proof amongst 
many that the practical system of teaching is the only 
one which yields good and satisfactory results. This 
method of experimental teaching is now coming more 
and more into general use, and perhaps to a greate 
extent in chemistry than in any other science. 
In the work before us there are 169 experiments care- 
fully described, most of which are suitable for the student 
himself to perform ; there are a few, however, the suc- 
cessful performance of which is almost beyond the capa- 
bilities of young beginners. The selection of experiments 
is left to individual teachers, and must depend to 
some extent also on the resources of the laboratory. It 
is a question ‘whether some few of them are not 
more suitable for the lecture table, or to be performed 
under the immediate superintendence of the teacher. 
It would, perhaps, have been an improvement if the 
author had distinguished those experiments which he 
thinks are necessary for the student to perform. This 
would certainly assist a student working privately, and 
would to some extent be a sort of moral obligation on — 
some teachers who might be inclined to run through the 
book superficially. Most of the experiments may be 
successfully performed if the directions in the book are 
adhered to, which are for the most part fully and clearly 
expressed. At the end of each chapter there is a short 
résumé, printed in italics, of the principal facts which 
have been demonstrated, and these form a very valuable 
part of the book. At the end of many chapters there is 
also placed a number of questions and exercises on the 
substance matter of the book, dealing, however, more 
| particularly with those points which are found to be 
stumbling-blocks to students. It is recommended that 
the answers to these should be written out and examined 
by the teacher, which, though it would involve a con- 
siderable amount of labour, would render the laboratory 
teaching much more thorough and efficient. 
the questions are by no means easy, and a student who 
can conscientiously answer them will have acquired a 
very fair knowledge of elementary inorganic chemistry. 
The notation used is the same as that employed by 
Dr. Frankland in his “Lecture Notes.” This, per- 
haps, may be a drawback to the use of the book by 
some teachers, although it appears that of late years 
this system has gained much ground. It consists 
essentially in the use of a series of compound radicals 
formed on the type of hydroxyl or peroxide of hydrogen, 
and in the employment of thicker type to represent 
certain elements which act as the grouping elements of 
each compound. Thus sulphuric acid is represented as 
consisting of the radical SO, combined with two semi-— 
molecules of hydroxyl, thus SO, (HO),, or, written 
according to the abbreviated formula, SO, Ho,, when 
Ho represents a semi-molecule of hydroxyl ; a sulphate, 
as, for instance, sodic sulphate, would be represented as 
SO, (NaO),, or SO, Nao,, in which the monad radical 
Nao (sodoxyl) has replaced hydroxyl, basic sulphate 
would be SO, (BaO,)", or SO, Bao”, in which Bao” is a 
compound dyad radical, consisting of one atom of barium 
and two of oxygen, and replaces the two semi-molecules 
of hydroxyl, The author uses the second of these formulae 
throughout the work, although, perhaps it would appear 
slightly less complicated if the first of these two kinds 
of formula had been used. This system of formulating 
bodies with the use of this class of radicals has been 
employed for many years in the field of organic chemis- 
try, so much so, that it is impossible to study this branch 
without being familiar with the system. We cannot see 
any reason why inorganic chemistry should not be treated 
in a similar manner, and we believe that this system will - 
gradually and surely spread, Graphic illustration is also 
employed, and is very useful in explaining the constitu- 
tional symbolic formule employed in the book. There 
seems no doubt that the fear that students would ma- 
terialise, as it might be called, these graphic representations 
—% 
Many of — 
res 
