142 



SCIUNGJE. 



[YoL. IX., No. 210 



the skin, by .121 of a second ; that two points 

 were touching, by ,194 of a second. The time 

 necessary for uniting three letters was shortened 

 by 1.956 seconds in 300 repetitions. In associat- 

 ing abstract words, there was a difference of 

 nearly five seconds between the longest and the 

 shortest time.' 



MINERAL PHYSIOLOGY AND PHYSIOG- 

 RAPHY. 



This book is a collection of essays which their 

 author has published during the past few years in 

 the proceedings of several learned societies, espe- 

 cially in the Transactions of the Royal society of 

 Canada. The preface states that they were all 

 written with a predetermined plan, which their 

 presentation in this connected form for the first 

 time fully realizes. The work will furnish a val- 

 uable addition to every geological library. There 

 is apparent in it an astonishing amount of learn- 

 ing and painstaking research, in spite of the fact 

 that the views of others are not infrequently pre- 

 sented in a partial or one-sided manner ; the au- 

 thor's conclusions also are well worthy of study, 

 although many of them will hardly be received 

 by geologists as final. 



It would be impossible, in a brief review, to do 

 justice to a single one of the essays, to say noth- 

 ing of the collection of them before us. The first 

 two serve as a general introduction and attempt 

 to show the relations of the natural sciences to 

 each other and to geology. Then are considered 

 in succession the chemistry of the earth's atmos- 

 phere ; the origin and decay of the crystalline 

 rocks ; a natural system in mineralogy ; a history 

 of pre-Cambrian rocks and serpentines ; and, 

 finally, the Taconic question. 



The most interesting and novel portion of the 

 work is contained in chapters v. and vi., which set 

 forth the author's remarkable views regarding the 

 origin of the crystalline schists. These, as he 

 states, are purely Neptunic or Wernerian. The 

 former hypotheses relating to the Archean rocks 

 are reviewed and classified as, 1°, endoplutonic ; 

 2", exoplutonic ; 3°, metamorphic ; 4°, metaso- 

 matic ; 5°, chaotic ; 6°, thermochaotic. None of 

 these are regarded as satisfactory ; and a seventh, 

 so called 'crenitic' theory is therefore advanced. 

 According to this, the globe has solidified regu- 

 larly from its centre outward, its last layer being 

 a basic, quartzless rock, not unlike dolerite in 

 composition. This mass was fissured and ren- 



' It is not quite clear whether these differences refer to 

 the extreme limits of a single experiment, or to the extreme 

 differences of the average of each set of fifty observations. 



Mineral physiology and physiography. By T. Sterrt 

 Hunt. Boston, Cassino. 8°. 



dered porous by 'refrigeration and crystalliza- 

 tion' (!) and upon it were precipitated the waters, 

 till then held in the atmosphere. 1 hese were set 

 in circulation by the heat from below, and under 

 high temperature and pressure they leached out 

 the more acid, alkaline silicates from the basic 

 substratum below, and deposited them in thick 

 layers at the surface, like the products of thermal 

 springs (hence the term ' crenitic,' from /cp^v??, ' a 

 fountain '). The chemistry of this process is sup- 

 posed to resemble that whereby quartz, orthoclase, 

 and the zeolitic minerals are occasionally deposited 

 in cavities of basic eruptive rocks. By such cre- 

 nitic action, in the author's opinion, all the 

 banded, pre-Cambrian rocks were formed. These 

 were, moreover, of such a thickness as to bury 

 the original basic substratum too deeply for any 

 subsequent upheavals to expose it at the earth's 

 surface. The crenitic hypothesis is also supposed 

 to offer "for the first time a reasonable and ten- 

 able explanation of the universal corrugation of 

 the oldest crystalline strata," in the removal of 

 such a large quantity of matter from the underly- 

 ing basic layer. Through these crumpled crenitic 

 rocks (Archean granites, gneisses, and schists) 

 came intrusions of a basic magma derived from 

 the underlying or original stratum, while the 

 upper or transition pre-Cambrian rocks, as the 

 author calls them with Werner, are regarded as 

 derived from the subaerial decay of the two types 

 of primary origin. 



The objections which at once suggest them- 

 selves to this remarkable theory of the origin of 

 the cr^talline rocks are far too many to be even 

 mentioned here. The leaching-out of a layer, ' at 

 least many miles in thickness.' of quartz and pot- 

 ash-felspar, from a basic substratum, requires suf- 

 ficient draughts on the imagination ; while, even 

 in case this be assumed as possible, it is still more 

 difficult to conceive how the waters could circu- 

 late through this compact overlying layer which 

 they were depositing, with sufficient freedom to 

 inci'ease it to anywhere near the thickness which 

 the hypothesis requires. 



No one will deny that any single one of the 

 nvrmerous theories hitherto proposed, fails to satis- 

 factorily account for all the phenomena exhibited 

 by the so-called crystalline rocks ; nor is it at all 

 probable that any theory ever will accomplish 

 this. There is doubtless some element of truth 

 in all the theories, and the only vray to explain the 

 diversity of Archean geology would seem to be by 

 the assumption of an equal diversity in the causes 

 which produced it. The dogma that many differ- 

 ent agencies may not have acted at the same time 

 in the formation of the pre-Cambrian rocks, is as 

 dangerous as the other, that the same agency may 



