XII PREFACE. 



nerals, and for the perseverance and patience with 

 which he has aided him in the correction of the 

 press. Dr TURNER also has favoured him occa- 

 sionally with his valuable assistance. 



The translator feels it an agreeable duty to ac- 

 knowledge, in the present place, that the addi- 

 tions to this work, and likewise the papers, which 

 he composed previous to its publication, owe the 

 greater share of any merit they may possess to 

 Professor MOHS, whose constant tuition in Mine- 

 ralogy, since the year 1812, he has had the good 

 fortune to enjoy, and of whose continued friendship 

 he has every reason to be proud. 



The following words of Professor MOHS, at the 

 end of his Preface to the first and to the second 

 volumes of the original, will form the best conclu- 

 sion of these prefatory observations. " The present 

 Treatise on Mineralogy is founded on principles so 

 ** different from those generally received in treating 

 ' of minerals, being in part in direct opposition to 

 " them, that it is not without hesitation that I have 

 " determined to lay it before the public. I have 

 " endeavoured to unite accuracy, correctness, and 

 u perspicuity, with as much of precision as I could 

 ec command ; yet I am perfectly aware that I have 

 not everywhere succeeded, and that this Trea- 

 " tise is in many respects imperfect. The task I 

 had to perform was nothing less than to apply 



