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N E W HOOKS.
T h e use of nitro compounds has, of late years, beconie so large that a rational niethotl of conducting the process of nitric acid distillation is imperatively called for. I3erthelot has shon.11that sti-ong nitric acid is coniplete1)-decorriposed at about 360" into nitroger1 peroxide, ox!-gcn, and ivater. I t is certaiii that \\.it11 t h r retorts entirely surrounded 1)). fire gases the temperature of the upper part of the retort exceeds IOO'. It is not surprising, therefore. that the first distillate should show a dark red coloi.. .4 recent distillatioii i n glass, with pieces of cast iron iiiiniersect i i i the tuisture of acid arid nitrate. gave no additional color to the first clistillate.
NEW BOOKS. nS I:. I'I.:CKl;,L MGI,I.ICK, I'H.D. 1.011d o n : Peter Moller. N e w York : \\*rn. IT. Schieffelin SL Co. Printed for private distribution.
C O I ) - L I V E K 011. A S D C H E M I S T K S .
T h i s book is reall) two books in one. T h e first part treats of cod-liver oil, the methods of catching the fish, the preparation of the oil, and an account of its constituents. W e learn that codliver oil was originally made froin fresh cod-livers by the steam process, by Peter Moller, i l l I8j3. T h e oil so prepared \vas a great improvemerit over the older product prepared by the putrefaction of the livers. I t still, however, caused disagreeable aftereffects when exhibited, and to reniedy this ail investigation was undertaken by P. b l . Hyerdahl, presumably in the employ of Peter Moller. Mr. Hyerdahl finds that the disagreeable aftereffects are caused by the presence of hydroxy acids in the oil, and that these may be excluded by reiidering the livers iii a n atmosphere of carbon dioxide. T h i s process is now carried out by Peter hloller, therefore buy your cod-liver oil of this firm. T h e deduction is not so stated ir; the book, which is well written and gives a very readable account of the subject, but the advertising purpose is obvious. I t is a pity that Mr. Hyerdahl's work was not made known through t h e regular channels-the Beyichtc for example. Chemists will be apt to look with suspicion upon statements so obviously interested.
NEW BOOKS.
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T h e second part of the book is a treatise on organic chemistry of an original sort. T h e author has used the Daltonian symbols in modified form, and the result is, a s might have been expected, that the poor devil of a printer has had a hard time of it. So long a s printing is done a s at present, authors should beware of using new characters: by so doing they not only increase the already difficult task of the printer but really put themselves a t his mercy. If only one printer have the character he must be allowed to do the printing of course. While such symbols have certain advantages, their disadvantages seem greater. Only a few people seem to be able to remember that, after all, our symbols represent only very imperfect knowledge, and that they are only tentative. A chemist can, therefore, read this treatise with interest and profit; it can scarcely be considered a good book for beginners, but it was probably not intended for EDWARD HART. beginners. T H E INCREASE I N WEIGHT OF TIN AND LEADON CALCINATION. BY JEAN REY, 1630. Alembic Club Reprints, No. 11. 54 pp. Edinburgh :
William F. Clay, 1894.
Rey is one of the less well-known investigators of the seventeenth century. H e is properly to be classed with Hooke, Mayow, and Boyle, or the Oxford School of Chemists, a s Thorpe has fitly called them, in their work upon the increase of weight of the metals when calcined, and the part played by the air in these processes. T h a t which Thorpe has so well done for the others is now done for Rey in this little book. T h e quaintness of the original is well preserved in the translation, and the book is very valuable a s giving an insight into the wisdom and the childishness of the times. His self-applause in the triumphant summing up of the evidence in support of his theory, that the air played an important part in the phenomena observed, is delicious. T h e Alembic Club is doing a most valuable work for the science in the republication of these early essays. They are interesting and helpful to the earnest student and should have a F. P. VENABLE. wide circulation.
