1-4 
writers of manuals no doubt felt it incumbent on 
hem to gild the pill by introducing such matter as tended 
o show that there was such a thing as/a practical appli- 
cation of chemistry to the Arts. 
However, that time has passed. Perhaps no science 
as of late become so widely popular, and certainly none 
hhas advanced so rapidly towards accuracy as chemistry. 
It is, therefore, time for it to throw aside the crutches 
upon which it was bound to support itself whilst struggling 
for recognition and public favour, and to march boldly 
forward, depending on itself alone. As a means to this 
end, it is with great pleasure that we welcome Mr. 
‘Crookes’s translation of Dr. Wagner’s work. He has 
given us, in the form of a handbook, what could only 
before have been obtained either by searching in special 
treatises, or by reading much more cumbersome diction- 
aries ; and the existence of this book cannot but have its 
influence in setting free much of the space hitherto 
occupied in educational works on chemistry, by perfunc- 
_ tory descriptions of technological processes. 
We most heartily join with Mr. Crookes in the hope he 
_ expresses at the end of his preface—“ We cannot let this 
work pass out of our hands without expressing the hope 
that, at no distant date, chairs of Technology will be 
founded in all our universities, and that the subject will 
be included in the curriculum of every large school.” 
_ Such an event could not fail to have the happiest effects 
_ onall; for, while it would set free the scientific student 
- from a subject he does not require, it would enable those 
-wishing to become managers of works or manufacturers, 
to study their special subjects in the best possible way.” 
_ The work consists of 745 closely-printed pages, with 
_ 336 illustrations, and a copious index. The subjects are 
treated at considerable length, and with extreme lucidity ; 
this is especially the case with the portions devoted to 
metallurgical processes, where every step is carefully 
traced, and all the latest forms of furnaces, &c., are repre- 
sented by woodcuts. We notice, however, that the 
section on electro-metallurgy is shorter than could have 
been wished, and that no mention is made of the process 
of depositing nickel upon iron, &c. 
In the section on explosive compounds, we have full 
_ details for the preparation of picrates, nitro-glycerin, gun- 
_ cotton, &c., ; though the author, perhaps led away by his 
chemical enthusiasm for these bodies, has treated gun- 
powder somewhat shortly, and the very interesting results 
obtained by the use of pebble, pellet, and prismatic 
powders, we do not see noticed at all; in fact, this article 
is decidedly behind the times. The preparation of salt, 
sulphur, soda, ash, bleaching-powder, &c., are well and 
fully treated, though we do not see Deacon’s process for 
the preparation of chlorine mentioned. 
_ The articles on glass and earthenware are remarkably 
- good and full, as are those on cements and fime, paper, 
_ sugar, and spirit. Since March 1868, two editions of the 
work have been issued, making eight in all. Of the eighth, 
and last, translations have been made into French and 
Dutch, and everyone will thank Mr. Crookes for the quan- 
- tity of new matter he has added, In conclusion, it need 
~ onlybe said that the formule: are throughout molecular,and 
that the metric system of weights and measures is used,'ex- 
_ cept where English quantities were indispensable. We feel 
 $ure that this book will permanently take its place among 
“5, oe es 5 Ee tae ee Ot 
ese Pere pe Pm pany, cara oem ae 
Pahl ics Bite aY 2: . a rat . 
s ’ 2 
f ie : + 
“NATURE : 
our manuals, and that the editor and translator will, in 
future editions, correct any little faults and errors which 
are, in so large a work, unavoidable ; while he will keep 
it fully abreast of the times. R. F, 
OUR BOOK SHELF 
Ueber die Bedeutung der Entwichelung in der Natur- 
geschichte. Von Dr. A, Braun, Berlin. 
Ueber die Auflosung der Arten nach natiirliche r Zucht- 
wah?, Von einem Ungenannten, Hanover. (London : 
Williams and Norgate.) 
THESE are two of the most recent of the numerous con- 
tributions which Germany has made to the literature of 
Darwinism. The first is an address delivered on the an- 
niversary of the medical and surgical Frederick-William 
Institute in Berlin, and is a tribute to the enormous im- 
petus given to physiological research by the promulgation 
of Mr. Darwin’s theories. The writer, however, while 
fully adopting the principle of Evolution, leans to the 
views which have during the last few years greatly spread 
among naturalists, that any theory like that of natural 
selection, which does not recognise an inherent law of 
progress, is insufficient to account for the phenomena of 
the transmutation of species. 
The second of these pamphlets is a more noteworthy 
production. The anonymous author also admits the prin- 
ciple of Descent by Evolution, but contends that the'carry- 
ing out of this principle, so far from leading, as is generally 
supposed, to a multiplication of species and to a graduay 
rise to more and more perfect organic forms, must neces 
sarily result in a gradual diminution in the number o- 
species, a fusing together of form after form, and a def 
scent to more lowly, instead of an ascent to more highly 
organised structures. With the origin of life he does not 
concern himself, but only with its future ; and the succes- 
sion of organised beings he compares not to a tree branch- 
ing out into infinite ramifications, but to a river uniting in 
itself an infinitude of smaller streams. Whether the propo- 
sition is a serious one, or whether it is put forward as a 
reductio ad absurdum by a furtive opponent of Evolution, 
it is difficult to say ; but the argument is carried out with 
considerable ability, and a strong point is made of the 
acknowledged degeneracy of many races of men from the 
condition of their ancestors, and of the gradual dying out 
of tribes and the consolidation of the human family into 
an ever decreasing number of types. 
LETTERS TO THE EDITOR 
[The Editor does not hold himself responsible for opinions expressed 
by his correspondents, No notice is taken of anonymous 
communications. | 
The National Herbarium 
You will, perhaps, give admission to a few remarks on Dr, 
Hooker's instructive ‘‘Reply ”* to my ‘‘Statement” of 16th May, 
1872, bearing in mind that;this ‘‘ Statement” was called for in 
explanation of the grounds of my requirements and assignment 
of space in the Museum of Natural History, to be built at South’ 
Kensington, for the reception, uses, ‘and applications of the 
National Herbarium, on the conviction that such would be con- 
tinued and maintained in the metropolis. 
Dr. Hooker had put in the van of his evidence,} and recom- 
mendations bearing on the reduction, limited applications,s and 
subordination to Kew ||, of the Herbarium at the British Museum 
* See Nature, vol. vi. p 516. 
+ Minutes of Evidence of Royal Commission on Scientific Instruction. 
t Ans. to Q. 6,683. § Ans. to Q. 6,684 and 6,685 
