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THE POPULAR SCIENCE MONTHLY. 



to this feature of the work, because the 

 current notion of the unattractiveness of 

 scientific writers is often made an excuse 

 for neglecting valuable scientific books, and 

 we wish to apprise those who are addicted 

 to this habit that the excuse is not valid in 

 the case of the present work. 



Chemical and Geological Essays. By 

 Thomas Sterry Hunt, LL. D. 489 

 pages. Price, $3.00. J. R. Osgood 

 &Co. 



Among the multitude of compilations 

 and digests upon scientific subjects, which 

 have been latterly put forth on both sides 

 of the Atlantic, by men whose names lend 

 no weight to their work, we welcome this 

 substantial volume by one who ha3 devoted 

 his life to the original and independent 

 study of the subjects with which it deals, 

 and whose high reputation, and the honors 

 he has received from learned societies both 

 at home and abroad, give the best assur- 

 ance of the valuable character of his la- 

 bors. Dr. Hunt has done the public an ex- 

 cellent service, in collecting and republish- 

 ing his chief scientific memoirs. His vol- 

 ume, indeed, was wanted. We have many 

 and excellent text-books of geology and 

 text-books of chemistry, but something 

 like a comprehensive text-book of the rela- 

 tions of these two sciences was a desidera- 

 tum in our scientific literature which this 

 work will go far toward supplying. For, 

 although it was prepared for no such pur- 

 pose, and although its papers were pro- 

 duced at different times in the course of a 

 life devoted to research, and of course bear 

 the stamp of the author's views, yet its 

 statements of facts are to be thoroughly 

 trusted, while their theoretic interpreta- 

 tions are so presented as to give us the latest 

 views that science has reached respecting 

 them. The volume is both a representa- 

 tion of the present state of knowledge upon 

 chemical geology and of the growth of that 

 knowledge during the past generation. In 

 no field has there been greater activity of 

 investigation, and, while Dr. Hunt develops 

 the views to which his own studies have led 

 him, he gives us at the same time the opin- 

 ions entertained by others, or previously 

 accepted, so that the reader is well instruct- 

 ed upon the subject, and is able to form an 

 intelligent judgment for himself. The follow- 



ing passage from his preface will give an idea 

 of the extent of the topics considered. The 

 author's " researches and his conclusions at 

 to the chemistry of the air, the waters, and 

 the earth, in past and present times ; the 

 origin of limestones, dolomites, and gyp- 

 sums, of mineral waters, petroleum, and 

 metalliferous deposits, the generation of 

 silicated minerals, the theory of mechanical 

 and chemical sediments, and the origin of 

 crystalline rocks and vein-stones, including 

 erupted rocks and volcanic products, cover 

 nearly all the more important points in chem- 

 ical geology. They have, moreover, been 

 by him connected with the hypothesis of a 

 cooling globe, and with certain views of ge- 

 ological dynamics, making together a com- 

 plete scheme of chemical and physical ge- 

 ology." Since the appearance of BischofFs 

 treatise on chemical geology, twenty years 

 ago (it was never republished in this coun- 

 try, and if we are not mistaken it is now 

 out of print), we have met with no book 

 that so fully covers the ground as this col- 

 lection of essays. It will be valuable for 

 reference to the students of economical ge- 

 ology, and interesting to general readers 

 who care to understand any thing about the 

 great agencies of Nature which have pro- 

 duced, and are still carrying on, the changes 

 in the crust of the earth. It will at once 

 take its place in the libraries of scientific 

 men, and should be introduced for refer- 

 ence into all schools where chemical and ge- 

 ological science is studied. 



The Principles of Sociology. By Her- 

 bert Spencer. Part I. Eighty pages. 

 Price, 50 cents. Published quarterly. 

 $2 a year. D. Appleton & Co. 



After an interval of some delay, Mr. 

 Spencer resumes the course of his philo- 

 sophical serial, and has now entered upon 

 what will generally be regarded as its most 

 important part. There has been much im- 

 patience, with many, that he has been so 

 slow in reaching the practical and pressing 

 problems of social science which he was ex- 

 pected to handle with originality and power ; 

 and readers have complained of the pro- 

 longed discussions in biology and physiolo- 

 gy which seemed to have nothing more than 

 a speculative importance. But we already 

 begin to see that Mr. Spencer understood 

 what he was about in his thorough elab- 



