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eddies of air which move forward with the storm, chiefly along the edge of it. An argument in favor of this is the precipitation of hail over comparatively narrow belts. Such eddies are formed hy the sudden uprushing of overheated moist masses of air into the high very cold levels during thunder storms, and also during the general disturbance of atmospheric equilibrium when a cold wind from above passes over the hotter lower layers of the atmosphere. Similar eddies often pass along the surface of contact hetxeen hot and cold layers of air, the phenomenon often being repeated a number of times. “Ferrel considers t h a t hailstones are formed in very violent uprushing eddies of air having small cross-sections, and he assumes that the xnall hailstones are vhirled upward repeatedly until their \\.eight has become so great t h a t they fall to the earth. The velocities called for in the eddies are not irnprohahle ones when we consider the effects produced h y local eddies, such as 1l.ilder D . Ha~zcrojt cyclones and tornadoes, even a t the earth’s surface.” Dr. I. Frick’s Physikalische Technik oder .In l e i t u n g zu Erpcr2‘iifciital;orfI U Y S~lbstiierstelliing eiiifaclier Demo,zsfrati~,zsuppa~ate.Sz‘ehciitc ~ o l k o m n t e i z iiingmrbeitefe u n d stark nernzchrtc .Iu,dage i o i i U r . O t f o Leirmutzi>. Zweiter Band. Ersfe .4btci!ztng. 18 X 26 cin; fip. .&z 762. Braunscii7;~eig: Friedrich I’ie;,eg 1 1 1 1 d Soiin, 1907. I’ricc: paper, 20; bourid, 22 mavks.--.\s the title itself shows. this hook is intended to be uf service to the lecturer jn physics both by showing just how certain experiments can lie performed and also I,? telling him from what firms he can h u y special apparatus for the experiments. The hook is eminently successful in both aims. The experiments in this volume are grouped under the headings: electrostatics; galvanism ; magnetism ; induction. There is a n extraordinary number of experiments and they are vary well chosen. Some of them are distinctly interesting for reasons other than their merit as lecture experiments. T h u s on p. 280 we find the statement that v h e n lead is precipitated electrolytically from a n aqueous solution, hexagonal crystals are obtained with a low current density and regular crystals with a higher current density. There are several experiments on the heliavior of isolated conductors in :in electrolytic solution through which a current is passing; but they deal chiefly with the special case of no polarization a t the surface of the interposed conductor. The revie\ver has always liked the experiment of the precipitation of copper from a copper sulpliate solution on a detached carbon rod the moment the fall of potential in tlie solution alongside of tlie rod exceeds a certain value. l l ’ i l d e ~D . Hancrojf rageii sowic
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Elementary Agricultural Chemistry. A Handbook for Junior Agricultural Students and Farmers. B y Herbert Ingle, 13 X 20 cm; pp. ix f 250. London: Charles Griffin and Company. Philadelphia: J . B. Ta,zppincott Company, 1908. Price: $1.50 net,-In the preface the author says: “This little volume is based upon the writer’s long experience in teaching agricultural students, among whom there are, unfortunately, many who cannot devote the time necessary t o acquire sufficient knowledge of pure chemistry t o profitably read such works a s the author’s Manual of Agricultural Chemistry.
S e w Books “It is true t h a t any a t t e m p t t o combine, in one hook, instruction in t h e principles of general chemistry with the somewhat technical information concerning the chemistry of agriculture, must be in many Tv-ays a failure, and the author would strongly recommend the user of this work t o read some good, modern test-book on the former; or, better perhaps, t o ask his teacher to explain, at greater length, the very incomplete and sketchy accounts which are given of the principles of chemistry and of the properties of the elements and compounds impoi tant in agriculture. “IT-hile fully realizing t h a t a satisfactory knoivledge of agricultural chemistry cannot be acquired Tvithout a previous training in pure chemistry, he is aware t h a t there are many agricultural students and farmers Tvho have, perforce, to d o without this preliminary chemical knon-ledge, and it is for such t h a t this book is mainly intended. “Since the irork is m i t t e n for the agriculturalist rather than for the chernist, ien- references to chemical literature are given. “The book was prepared irhile the author ii-as in touch with many oi tlie crops and agricultural practices of South Africa. and it \vas thought advisable to give some account or’ the products of tropical ant1 sub-tropical agriculture in addition to the matters relating t o ordinary English farming. “In these days of frequent travel and emigration, such inclusions may be of service to many agricultural students who, in the future, may become Colonists, \rhile it may render the hook more suitable t o tlie needs of the Colonial reader, and t o all a co~nparisonof tropical irith temperate conditions, cannot fail to be L l d d “E\-ery Trriter is a p t t o give undue prominence to tlie particular subjects upon \rhich he has liiiiiself \~-orketl.and perhaps suine examples of this xeakness may he found in the present mlunie. “The importance of t h e compnsi~iona i -.\.ell as the aniount oi the as11 constituents of tlie iood of aninials. to vliich rcierence is rnatle in chap. i s . , though perhalis not strongly felt in Europe iihere diet is varied, is ccnsitlerable in such countries as South Africa, \!-liere the us~.ialfood of draught animals is composed almost. entirely of cereals. “ I n c i i a p iii., a brief account is +\-en of tlie main cauSes oi the motion o i ii-ater in a soil, intentied to clear a r m y rhe confusion \Yhicli is a p t t o attend the uiua! ‘,explanation” as to its being due to “capillarity.” C11:ip x.deals with the variation.; in tlie cornposition of COIT’S milk in greater detail. pci-liaps, tlian the elenicntary character of the book justifies: b u t liere again tlie popiilar interest a t prcsent shon-n in tlie subject must lie the escuse. “There arc doulJtles>,other resljccts in !\-liicli the irork is “out of balance,’’ but lor t h e x , the reader’? indulgence is solicited. “The author hopes, in silite of this. t h e h o k may prove of service to those T l ~ i l d ~Di .. liuiicrojt for \rlioni it is i n t e n d d ” Cows de Chimie Inorganique. I:?, Frid S?,art?. 16 X 2.j cnz; p p . 7 0 6 . Pa,r.(: -1. H c r r m i z i ~ ,190i’. P Y J C paper. ~: r j jroim-This book is based on the lectures given by the author a t the University of Ghent. I n some respects, the \-olunie is very much u p to date. The Rirkeland and Eyde process for making the oxides of nitrogen is described a t some length. I t is interesting t o note
