Dee. 8, 1881 | 
the typical forms are thereby necessarily increased. Jn 
order to preserve the just proportions of the subject, and 
out of the whole make a fair selection, I have treated 
most of the forms in less detail than the Vertebrates.” 
With the above statement no objection could be found ; 
as to the method of carrying it out, we notice that 
while four out of the sixteen plates are devoted to 
illustrations of the group of Protozoa, there is not 
even a single figure given of the Sponges, nor of the 
Hydrozoa, nor of the Actinozoa, and for their absence 
we can find no other excuse than what is given in the 
above quotation. As to the plates of Protozoa, we 
perceive that there is no exact indication of the size of 
the forms figured, unless indeed in a footnote, which 
states that the forms figured ‘‘are all wzzcroscopic, with 
the exception of the Nummulites.”’ Now if there is 
one thing more than another that a student requires 
to be reminded of while studying “microscopic”? forms, 
it is that they vary immensely among themselves as 
to size, and it is surely necessary that he should have 
some definite ideas as to those sizes beyond the range of 
unassisted vision, such as he may be presumed to have of 
those objects within this range. Neither has the author 
been to our mind happy in his selection of forms of the 
Protozoa “from standard works on the subject.” His 
Atlas is meant for students in this country, and where are 
they to get specimens to work with of such genera as 
Protogenes, Vampyrella, Myxastrum, Protomonas, Proto- 
myxa, Lieberkiihnia, and the like. The student interested 
in ‘‘pond-life”’ may possibly admire the exquisite and 
artistic delineations of their old favourites, Paramecium, 
Daphnia, Cyclops, &c., giveninthe Atlas. The festooned 
surface of Paramecium, the appendages of Daphnia and 
Cyclops are certainly figured as they have never been 
heretofore. It is really refreshing to turn from the old 
and well-worn figures to the bold originality of these 
plates ; in them the author has courageously followed 
the theory of zoological representation laid down by the 
celebrated German artist with reference to Camzelus, sp., 
but is scarcely to be congratulated on the wonderful 
results he has achieved. Some of the diagrams are 
acknowledged as from the originals of Huxley and 
Gegenbaur ; these are good. 
The Student’s Handbook of Chemistry. With Tables 
and Chemical Calculations. By H. Leicester Greville, 
F.1.C., F.C.S. (Edinburgh: E. and S. Livingstone, 
1881.) 
“Tn the presence of so many good manuals on chemistry, 
the appearance of another may seem unnecessary,” says 
the author in his preface. For “may seem”’ read “is,” 
and the sentence expresses a truism, The author’s 
book can, however, scarcely be classed amongst ‘‘ good 
manuals.” The statements of individual chemical facts 
are on the whole correct ; the general arrangement of the 
book is clear; yet, considered as a manual of chemistry, 
the work must be pronounced a failure. 
Attempts are made to explain the expressions “ atomic 
weight,” “ molecular weight,’ “valency,” &c., but without 
success. Atoms are confused with molecules ; the ordi- 
nary definitions of these terms are certainly stated, but 
definitions taken by themselves are, as Hunter said, ‘ Of 
all things on the face of this earth the most cursed.”’ 
Avogadro’s law is stated on p. 26, but the conclusion 
deduced therefrom, viz. ‘‘the densities of all the elemen- 
tary bodies in the gaseous condition are the same as their 
respective atomic weights, or, the atoms of all the elements 
in the gaseous state occupy the same space,’ is untrue, 
and does not follow from the generalisation of Avogadro. 
The Daltonian atomic theory is stated much in the 
terms which might have been employed before the mole- 
cular theory of matter had been propounded. Such 
statements as that on p. 15, that oxides are called monox- 
ides, dioxides, &c., according “as the compounds contain 
one, two, three, &c., atoms of oxygen respectively”; or 
NATURE 
ch ie 
that on p. 13, “that acids are spoken of as monobasic, 
&c., according as they contain one, two, &c., atoms of 
hydrogen replaceable by a base,” show that the author 
has failed to grasp the teachings of the molecular theory. 
The term “valency,” we are told on p. 159, is used to 
express “the comparative saturating power of the differ- 
ent elements, taking hydrogen as the unit.” Such a loose 
statement as this naturally prepares the way for the full 
acceptance of the ‘‘bond’”’ view of valency, with all its 
inconsistencies and apparent, but unreal, explanations of 
facts ; so that one need not be surprised to find (p. 160) 
the expression, hard to be understood by the uninitiated, 
“the affinity of these bonds.” 
A sentence on p. 161 may be quoted as a type of the 
kind of writing to be found in the works of those who are 
bound by the trammels of this pernicious system. “The 
disappearance of the active atomicity by twos, which is 
found to be always the case, has led Dr. Frankland to 
suggest that the bonds of union so disappearing are 
engaged in satisfying each other.” 
That part of the chapter on “ The Higher Principles 
of Chemical Philosophy’’ which deals with compound 
radicles is equally unsatisfactory. Sulphuric acid may be 
assumed to contain the radicle SO,. “The group SO, 
may be traced all through the compounds of sulphuric 
acid, thus: SO,(O0K), SO,(ONa), SO,CuO,.”” Such a 
statement is harmful, and only harmful, to the student ; 
in what light other than as an amusing plaything can 
he regard this conception of compound radicle? Why 
should he not trace the group SO,, or the group SO, or 
the group SO, “all through the compounds of sulphuric 
acid”? Give him pen and paper, and if he have a little 
fancy he will trace you a most varied and pleasing 
number of groups “all through” as many compounds as 
you please. 
The tabulation of facts concerning groups of elements 
and compounds is a good feature in this book, and likely 
to prove very useful to the student. The chapters dealing 
with organic chemistry are clear and succinct: had the 
author contented himself with recording leading facts, 
and left the ‘principles of chemical philosophy’’ alone. 
he would have produced a book of some merit, although 
not of merit sufficient to warrant him in adding another 
“ Manual of Chemistry” to the list which is already sa 
much too long. 
LETTERS TO THE EDITOR 
[The Editor does not hold himself responsible for opinions expressed 
by his correspondents, Neither can he undertake to return, 
or to correspond with the writers of, rejected manuscripts. 
No notice is taken of anonymous communications. 
[The Editor urgently requests correspondents to keep their letters 
as short as possible. The pressure on his space is so great 
that it ts impossible otherwise to ensure the appearance even 
of communications containing interesting and ncvel facts.) 
The ‘‘Eira” Arctic Expedition 
THOSE who advocate the despatch of a Government vessel 
in search of Mr. B. Leigh Smith’s expedition betray only 
a partial acquaintance with the circumstances of the case. 
His having failed to return this season is no evidence what- 
soever of his having met with disaster; for previous to his 
departure from England, certain people well understood that 
he was prepared to spend the present winter far north if he 
found it worth while to do so. It was this which prevented me 
from going with him (natural history work on hand precluding 
my absence from London for upwards of a year); for as I 
had collected plants and animals with him on a former expe- 
dition in Spitzbergen, he invited me to accompany him on 
his present trip to Franz-Josef Land. The £2z7a was well-pro- 
visioned for upwards of eighteen months, and in summer time 
fresh meat in abundance can be secured, which, hung up in the 
rigging, will keep good for almost an indefinitely long period. 
Thus the expedition has provisions enough for at least another 
year and a half from the present time, and there would be no 
need for them to starve two years hence. It is therefore rather 
