THE ANALYST. 10s R E V I E W S . THE PRINUIPLES OF THEORETICAL CHEMISTRY, WITH SPECIAL REFERENCE TO THE CONSTITUTION OF UREMIUAL OOMPOUNDS, By Ira Rernsen, H.D., Ph. D.Pro$ssor of Chemistry in thihe JohB Eipkins University, BaZt%mop.e. London : Bailliere, Tindall and Cox, 20, King William Street, 8trand. WHEN the first edition of this little book was published.some years ago, it then struck u8 as eupplying a distinct want, by bringing together fully, and yet within a limited qace, the so-called theories of ohemistry. The present edition is much improved, and the chapters on atomicity, and the constitution of carbon compounds, have been extended and revised, with the result of increasing their value. The great object of the work consists (while dealing with all the known hypotheses), in showing the exact connection of each theory of the constitution of bodies with its experimental proof, and so keeping the mind of the student clear, as to how far it is safe to run after any particular idea.To follow the author’s words, we know that-he considers harm has been done to the science of chemistry, by a too free use of hypotheses, on the part of those who are ignorant of the facts which suggest them. This has been, and is, particularly noticeable, in connection with the use of structural or constitutional formula, and it is heart-rending to see the merest tyros in ohemistry, employing such expressions with a freedom which may well astonish one who knows their true significance. An exporience of years, has led Dr. Remsen to the COILC~S~OII, that these formulm are used by students without any clear understanding, and the great object of his work, is to do something to correct this evil.It must not, however, be thought that upon this point the author is a Don Quixote, with con- stitutional formula for his windmills, because, (page 102,) when discussing the various possible modes of expressing acetic acid, he says :-*‘ It must be distinctly stated, that we cannot use the valence hypothesis, except to supplement the reaction and synthesis formulm. We are not justified ingoingbeyondtlie facta established. Here lies the danger in the use of rrtructural formulm. Their wholesale use, to express something about which we know absolutely nothing, has tended to bring them into disrepute, but this fact should not cauae their entire rejeotion, for there is, undoubtedly, muoh of value in them, when rightly used.” These words appear to us a very just estimate of a much debated question .among chemical teachers, and show,the care of the author in not following too much in a groove.Again, upon another page, we find the following cogent remarks :-‘‘ I t cannot be denied that we are now in a period of chemistry which may fairly be called formzcla womb@. By weaker minds, more value is attached to &formula, than to that which it is intended to represent. In consequence of this truth, it has happened that a large number of chemists have regarded the determination of a formula for a compound, as a great object to be accomplished, and forgotten that what we ought to know, and what is of vastly greater importance for the science, is the chemical conduct of the compound. If, knowing this, we can represent it by means of aformula, not only are we justified in doing so, but the formula becomes an efficient aid in dealing with the substance.” The work, commencing with a study of atomic weight and volume, proceeds, in the fifth chapter, to deal with atomicity, or valence of elements, and this will be found to be very exhaustive and carefulIy writton.AU the various ideas of ordinary atomicity,104 TEE ANALYST. difference in valence of atomic and molecular compounds (which the author condemns as really an unnecessary distinction), double linkage and variable valence, are fully discussed, and the exact extent of experimental proof, upon which each idea is based, is fully detailed.Dr. Remsen finally inclines to agree with Wurtz, in considering that valence really ought to mean, not the absolute power an atom has to hold other atoms in combination, but rather the power it actually exhibits in any given compound ; thus abandoning the idea of valence as ordinarily defined, and substituting for it a variable idea, depending on the nature of the compound which the particular atom forms with others. The discussion of all the experimental proofs upon which we base our consti- tutional formula in organic chemistry is exceedingly plain, and will be found of the greatest value to a student already possessing some general knowledge of the chemistry of carbon. Such an one, sitting down to the last section of the book, will rise up with the whole subject clear before his eyes in a perfectly different light to what he has probably before seen it, and he will most likely heave a sigh of relief, and say to himself that organic chemistry, is, after all, not the dreadful thing he hitherto thought it, It is not a book for a beginner exactly, but for a student in, as it were, the transi- tion stage from junior to senior classes, it will be found invaluable, and as such, has our sincerest commendation. A SHORT TEXT-BOOR OF INORG~IC CHEMISTRY.By Dr. 2&ermann Xolbe, Professor of Chtsmi8try ilz the University of Z e i p g . Transhted and Eda’ted by 2’. 8. Himpidge, Ph.D., B.&, (Lond.) Professor of Chemistry and Phy8ics a’a ths UfiherSity College of Falea, B6erptwyth.London : Longman’s, Green and Go. WEILE granting a real raisolz d’ktre for Dr. Remsen’s book, just passed in review, we cannot extend the same admission to the present-work, even in the face of the Editor’s hope in the preface ‘‘ that it will supply a definite want among teachers and students, corresponding to that which the Editor has himself felt.” If Dr. Humpidge has found so great a vacuum in respect of suitable short treatises by English chemists on this subject, that he has been driven to translate the work of a German author to fill it, then we fear he must have lived too much the life of a chemical anchorite, because their name is already legion. The Editor gives the Author’s preface (which is practically a Bhort lecture on the necessity of attending lectures, and how far the lecturer should go beyond general principles into the domain of descriptive chemistry), and takes care to state that he fully agrees with the propositions therein formulated. This is very much like putting up a mark to shoot it down again, because it is the exact principle upon which most of our short manuals are compiled.While, therefore, denying any real want of such a fresh addition to this class of book in toto, and looking upon it simply as one pro- duced, as is only natural, by a professor for his students, we must admit that it is very well and clearly written, and that it is quite up to, and in some few respects beyond, the common standard of such text-books. The ;Editor must be complimented upon seeing chemical work through the press with SO few misprints, and upon a well written appendix, dealing with the determination of atomic weights, periodic laws, &c., which wascertainlysorely required as an addition to the body of the book to make it aufEciently advanced for the class of London University students for whom he translatedTHE ANALYST.105 it. One great defect, in om opinion, is the way in which chemical theories are scattered through the book in a disjointed form. The formulm used are reaction ones, but, in common with some other similar manuals, the &planation of the conRtitution of salts is deferred to the three hundred and thirty-first page, a d so we have a student faced on page 100 with an equation including SO, [ g?, and an explanation of what such a thing means on pages 333, el seg.Our own idea, l p s always been, that before submitting an equation to the gaze of a student, some tolerably complete explanation should be given of the meaning and construction of formuJe, instead of scattering it over the book and so making the pupil st once take a horror of equations; but upon this point we know that we differ from some other writers. The work reads exceedingly well, the print is clear, the volume is handy to hold, and we have no doubt it will be found useful by the Editor’s students, but there is nothing striking in it as showing the superiority of foreign over native talent. From the specimen of the Editor’s work in the appendixhe might have produced quite as good a book on his own account as this one he as borrowed from the German, and with as little trouble, but we suppose that the name of Kolbe, appeared a good one to conjure with, in the eyes of that section o€ the reading public who believe in everything foreign in preference to the native article.HANDY GUIDE TO PUBLIU HEALTH, FOR THH USE OF MEDICAL OFSICERS OF HEALTH AND ISSPEUTORS OF NUISANCES. By Z’! EWteside Hime, B.A., XB., Hedical Ofleer of Health for the BoroNgh of &&ford, kc., &c. London : Bailliere, Tindall, and Cox, King William Street, Strand. THIS book will prove a great desideratum to %hose for whom it is intended, for, in a compass of 160 pages, bound in limp leather, and just the size of an ordinary breast pocket book, we have a digest of the whole Acts relating to public health in every form. Besides the Public Health Act of 1875 itself, we find digests of the Sale of Bood and Drugs, The Rivers’ Pollution, The Canal Boats, The Factory, The Infant Life Protection, The Burial, The Artisans’ Dwellings, The Contagious Diseases (Animals) Acts, besides many Orders in Council.To sum the merits of the book up in a word we should say that no medical officer or inspector with it in his pocket need ever be at a loss how to act in any emergency that he may be suddenly placed in. Eaving said this so far as the general usefulness of the book is concerned, we must take very grave exception to a portion of it which professes to give information upon the duties of inspectors and medical officers, under the Sale of Food and Drugs Act, on the subject of milk. l n the flrat place we find a table of mi& analyses professing to show the percentage of added water by an old scale of Dr.Letheby’s, based upon specific gravity and cream, and following this we find (page 176) these remarkable words, “The lactoscope of Professor Fewr is admirably suited for rough and rapid determinations of the quality of milk. Any aample indicated a8 W by the lactoscope and densimeter, the examination only taking a few minutes, sho~ld be sent to the arta@pt,” The italics are ours and are meant to indicate the mischievous doctrine herein laid down. There is no provision in the Act €or any tampering with the semples taken by the inspector pre- vioiisly to their submission to the analyst. In point of fact it is quite the contrary,106 THE ANALYST. because, in cases where the vendor does not require a sample, the analyst must divide with his own hands, and not even the inspector. So far as this Act is concerned, the inspector has to buy with proper precautions, seal, and convey to the analyat direct, and the medical officer has no Zocus 8tandi whatever to interfere in any way, This piece of advice to medical officers to interfere with the duties of brother officers is a gratuitous throwing down of a bone of contention between two pereons who should be ever ready to help and eupport each other by advice and general co-operation. But, worse than this even, it ia playing into the hands of adulterators, because such a tampering with any portion of the official quantity of milk purchased by the inspector would certainly constitute a good defence to any subsequent proceedings upon the sample if found bad by the analyst. It is very possible that thie blot slipped into an otherwise good book unawares, and now it is pointed out, we hope that the author will excise it in the next edition.