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POPULAR SCIENCE REVIEW. 
of his volume as specially deserving perusal. And such, we should say, 
are all those parts relating to the structure of the heart and the arrange- 
ment of the fibres in such a peculiar manner as to produce those motions 
which to some people are so inexplicable. The part of the work that deals 
with the structure of the heart, and the peculiar arrangement of the 
valvular provisions, is one that we must strongly advise our medical readers 
to peruse. In it they will find the correct explanation of much of the 
movement of the heart given, and that, too, by the most distinguished 
modern student of this wonderful construction. We can only express in 
conclusion our deep sense of gratitude to Dr. Pettigrew for the very able 
manner in which he has discussed, so as to be familiar to any well-educated 
person, some of the most complex problems in the whole range of phy- 
siological science. 
TEXT-BOOKS ON CHEMISTRY.* 
I T is strange that the idea has not occurred to any English writer that a 
book written in explanation of the immense and novel strides that 
chemistry has made within the past fifteen years would prove an extremely 
interesting book to the man of scientific mind. But it often happens that 
he who is outside the range of workers, no matter what their subject may 
be, often sees more clearly the entire relations of the labour than he who is 
engaged in it. u The best hurler,” says the Irish proverb, “ is always by 
the ditch.” And so it has happened in the present instance, for the only 
book that has been published on the subject of the changes that have 
occurred in chemistry — at least the only one that is especially a survey of 
the science as it is, compared with what it was — is a book of American 
authorship. Indeed, so far credit must be given to our transatlantic brethren, 
but we fancy not very much further. Throughout the book, although 
in many cases the author sees perfectly plainly the picture that is before 
him, and in some cases appears to put it more clearly before his audience 
than it is before himself, yet there are points on which, we confess, he 
seems to us to be decidedly in the wrong. It is of course not for us to deal 
with such questions here as the law that was laid down in 1811 by 
Avogadro with regard to the constitution of substances. Nor is it to be 
expected that we shall deal with the questions of quantivalence and 
metathesis in these pages. But it seems to us as if the author, gifted as he 
is with a remarkably clear power of explanation, has gone farther than mere 
fact will allow him. In any case, whatever view may be ultimately taken 
of the theories he has put forward, all must allow that he has written ably 
and clearly on a subject on which, while we have many men among us who 
are practically versed in it, we have, nevertheless, but very few who are 
* “The New Chemistry.” By Josiah P. Cooke, Erving Professor of 
Chemistry and Mineralogy in Harvard University, U.S.A. King & Co., 
1874. 
“ Introduction to the Study of Organic Chemistry. The Chemistry of 
Carbon and its Compounds.” By H. E. Armstrong, Ph.D., E.C.S., Professor 
of Chemistry in the London Institution. London: Longmans, 1874. 
