250 SCIENCE PROGRESS. 



It is difficult to believe that these were really the prin- 

 ciples of the science little more than sixty years ago ; but, 

 as a matter of fact, even before it had emerged from this 

 Slough of Despond, systematic mineralogy was based upon 

 experimental methods without which the chemical, physical 

 and morphological characters of minerals cannot be deter- 

 mined. 



The study of minerals, however, is no more limited to 

 the determination of their characters than is the study of 

 geology confined to the classification of fossils. A no less 

 important branch of the subject is occupied with the 

 investigation of their origin and the changes to which they 

 are subject ; even here experiment is not a new thing ; as 

 early as 1801 James Hall showed that chalk may be con- 

 verted into crystallised calcite by heating it under pressure 

 in a closed tube ; and after an interval of nearly a century 

 the same methods and almost the same apparatus are 

 being used in the synthesis of other minerals. 



But there is yet another aspect of the subject which is 

 the very life and essence of mineralogy if it is to exist as 

 a science at all : namely, the discovery of the general laws 

 of which the characters and changes of minerals are an 

 expression ; the relations between their chemical, physical 

 and morphological characters ; the molecular properties and 

 structures which are to explain both their nature and origin. 



In these matters, until recently, mineralogy was no 

 more occupied with experimental methods than were socio- 

 logy or astronomy ; and yet the mineralogist could not 

 plead as an excuse that his materials were either too un- 

 wieldy or too distant to be brought within the scope of 

 experiment. 



Regarding chemical and crystalline structure, for example, 

 numerous speculations exist ; but scarcely a single working- 

 hypothesis capable of any wide application ; the same is true 

 of questions relating to the genesis of minerals. 



The fact is that the science has experienced a tempor- 

 ary check owing to the want of experimental evidence by 

 which the theories might be tested. Even the classification 

 of minerals, the first and most important step, is at a stand- 



