June 1, 1900.] 



SCIENCE. 



861 



coals of the Lower Coal Measures of the East, 

 including the Morris or Mazon Creek coal of 

 Illinois and the Brookville or Clarion coal of 

 Ohio and Pennsylvania, hut previous to the 

 Darlington or Upper Kittatinning coals of the 

 latter States. A comparison with the British 

 coal flora indicates that the flora of the Henry 

 county deposits is represented to a greater ex- 

 tent in the Upper and Middle Coal Measures of 

 Great Britain than in the Lower ; probably in 

 age about that of the basal portion of the Upper 

 Coal Measures of that country. Interesting 

 comparisons are also made with the coal floras 

 of Continental Europe. It is to be regretted 

 that in this, as in all similar large works, many 

 of the finer points in comparative biology are 

 necessarily omitted or else are more or less 

 hidden in the mass of the systematic arrange- 

 ment. There is no doubt that several of the 

 species are capable of even more critical treat- 

 ment that is given to them, but every one must 

 recognize that the author has performed an 

 immense amount of investigation and has pro- 

 duced a work of permanent scientific and eco- 

 nomic value. Arthur Hollick. 



Analyse mierochimique et spectroscopique. By M. 



-E. Pozzi-EscoT. (Encyclopedic scientifique 



des aide-m6moire.) Paris, Gauthier-Villars, 



Masson et Cie. P. 192, figs. 40. 



Chemists the world over, have awakened, 

 within the last few years, to the fact that the 

 microscope is a most valuable accessory to 

 every laboratory of chemical analysis. This 

 increasing interest has been remarkably slow 

 considering the almost inestimable value of this 

 instrument as an aid in chemical research. The 

 failure, in the past, to. make use of the micro- 

 scope has been, doubtless, due to two causes : 

 first, the fact that instruction in the use and 

 manipulation of this instrument has not been, 

 heretofore, included in the courses of study 

 oflered to students fitting themselves for 

 chemists in the various educational institu- 

 tions ; second, there has been a lack of suitable 

 text-books, manuals, etc. The latter cause has 

 been eliminated by the recent publication of 

 several works. Of these the latest is the little 

 compend of M. Pozzi-Escot published under the 

 title given above. The appearance of this out- 



line of the methods of microchemical analysis 

 can be taken as indicating an increasing appre- 

 ciation of the great value of the microscope to 

 chemists, and friends of the system will, there- 

 fore, gladly welcome the little book although it 

 is almost entirely a compilation of methods and 

 reactions already published. It is but fair to 

 the author, to state, however, that the material 

 has been well chosen and due credit has been 

 given to the originators of the different tests 

 and processes. 



The author gives a concise review of the rise 

 and development of microchemical analysis. 

 Then follows a description of the requisite 

 apparatus and reagents, the tests for the dif- 

 ferent elements, and finally a more detailed 

 discussion of the methods to be employed in 

 the systematic analysis of unknown substances. 



It is greatly to be regretted that the elements 

 have been arranged in alphabetical order and 

 that no details are given as to the way of apply- 

 ing the tests, nor (save in a few cases) of the 

 causes which may lead to their failure. Any 

 attempt to make microchemical analysis a 

 purely mechanical matter is certain to give the 

 beginner no end of difficulty and, moreover, is 

 apt to mislead him into the idea that a knowl- 

 edge of chemistry is not an essential in the 

 interpretation of the tests obtained. 



Reactions for sixty-three elements are given, 

 most of which are satisfactory and are illustrated 

 by original or copied drawings of the crystals 

 to be obtained. 



Chapters III. to V. , dealing with the methods 

 to be employed in a systematic analysis, are 

 much better than those preceding. The neces- 

 sary manipulations being described in detail 

 and cautions as to sources of error are also 

 given. This portion of the work can be con- 

 sulted with profit by all those interested in the 

 neat and elegant methods of microchemical 

 analysis and renders it worthy of a place in the 

 analytical laboratory. 



That part of the book devoted to spectroscopic 

 analysis comprises only nineteen pages. It 

 would have been better had the author omitted 

 this section entirely and devoted the extra 

 space to a more thorough discussion of re- 

 actions and to an index. e. M. Chamot. 



Cornell University. 



