chalk wlieru the infusorial silica occasionally aegi'egal»?8 fiito cracks inatead of into flint nodules.
The breaking -do wu of tlic material of the walls of vein-fissures, its alteration, and incor- poration, in [)lacc, into the gangue, are briefly bnt well described, and illustrated bj drawings made from thin sections under the microscope. Much weight is given to the results of Sand- bei^er's researches, which seem to establish <juile firnilj' lateral secretion as the generally most important method of vein Ibrmation and enrichment. Mr. Phillips gives in this con- nection a very inatructive risumi of some of Sandberger's results, which show the wide- spread distribution of both the heavy metals and the elements of the gangue substances in the constituent minerals of the common rocks.
Not less int«]-osting are the instances cited to show the sulticiency of causes acting now and in receut times at the surface of the eartb. to cause the concentration and fisatiou of minerals lo form ore-bodiea.
Thus the fact shown by Sandberger, that all lithia micas contain tin, taken in connection with the tlnding, in various Cornish stream- works, of deer's antlers completely replaced by crystallized oxide of tin, points at once to the existence of sufficient sources of tin in surface rocks, and to the possibility of deriva- tion fiom those sources, and coucen ligation in veins and stock-works, under conditions now prevailing at the surface. So, also, in the instances of metallic gold which have beeu found deposited on the woodwork of Austra- lian mines, wc have similar evidence of metal- lic deposition now in progress.
While Mr. Phillips consitlers that the evi- dence is largely in favor of assigning to lateral secretion the generally most important part in fbrming fissure-veins, he recognizes the prob- able action of ascension, and also of sublima- tion, iu many individual cases. The portion of the book — about five hundred pages — devoted to the description of typical forms of deposits throughout the world is full of information desired by the economic geologist and the statistician.
The illustrative instances are weU selected, and the latest aviulable statistics of production are given, apparently, in uU cases. Aside from tbe fact that it brings the description of the countries treated by Cotta down to the present time, the book is particularly valuable for its descriptions of practically all countries which, for various reasons, received little or no atten- tion in Von Cotta's work.
��THE MICROSCOPE IN BOTANY.
TiiDSE studentffwho have lieen wniiinfi for an English translation of Behrens's book on botanical methods can but be disappointed now that it has appeared. Notihnt the book does not contain much that is extremely valu- able, nor that it is not put in an attractive form by the publishers, but that it has been made cumbersome and expensive iiy an inordinate amount of ' padding * not found in the German text. Figures and descriptions of .A.mericKn instruments are introduced with such carefnl discrimination, that doubtless the volume must prove eminently satisfactory to their makers. while the author's remarks on the more nseAiI stands of continental make are entirelv suj>- pressed, possibly (Vom a laudable wish to fur- ther home protection. The maxim of the author, that "■ be is the best experimenter who does bis work with the simplest possible appi "" ratus," is frequently outraged hy the descrf tion of gimcracks easily dispensed with, ai more properly advertised in au instrumei maker's catalogue than in the pages of an pensive handbook.
Yet, notwithstanding the fact that a L... dollaf-and-a-half book has been evolved into five-dollar book by a process the reverse natural selection, the translation must prov boon to the few investigators who have aufflcient command of German to use the origi-' nal; and it is unquestionably more i^nvenient for college students, who, as a rule, dread man- uals in any language but their own. Tlioae who use the book in either form will probal agree with the author that the chapters on agents and their application in microchemii
work constitute its most valuable feature^
dering it, indeed, indispensable in the labon^ tory where careful work is carried on. afm chapter on the preparation of sgiecimcns ftu'T examination and preservation is also extremelv; useful, and especially the |H)rtion treating of the preparation of fossils and other hard ob- jects.
Though a few more or less deserved slurs on English microscopists, and the author's all but complete forgetfulueas limt Americans ever look through the insti-ument, may touch the pride or appeal to the belligerence of an Anglo- American, the book is, iu the main, written well and in good taste, and shows a working familiarity both with the subjects handled tnS the literature pertaining to them.
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