> Introduction. xi 



that instrument which must still further diminish our 

 confidence in his results. 



Dr. Wollaston in the year J812 discovered that 

 these species differed from each other, and noticed 

 their differences in a paper published in the Philoso- 

 phical Transactions for that year. He found carbo- 

 nate of lime to measure 1055' 



Bitter spar 10615' 



Carbonate of iron 107 



Notwithstanding the discovery of these facts, which' 

 have been so frequently verified by subsequent mea- 

 surements, the Abbe Haiiy has not only continued to 

 insist on the superior accuracy of his own measure- 

 ments, but discusses through several pages how 

 it could have happened that the iron should have dis- 

 placed the lime in the crystals of carbonate of iron, 

 which his original error has led him to regard aspseu- 

 domorphous I 



With all the faults, however, which the late Abbe's 

 works contain, many of which we must in justice to 

 his better judgment ascribe to feelings of a personal 

 nature, those works present to the reader truly phi- 

 losophical views of the sciences of which they treat, 

 and they cannot be perused without frequently afford- 

 ing him both gratification and improvement. 



riip 



