330 Extract of a Letter from Mr. Breithaupt [May, 



Article III. 



Extract of a Letter from Mr. Breithaupt, in Freiberg, to 



Professor Gilbert.* 



You are aware that different chemists have found boracic acid 

 in the tourmalin, axinite, &c. of which essential constituent the 

 most celebrated former analyses have not taken the least notice. 

 These researches were undertaken at my request. I have been 

 employed these five years in endeavouring to construct a mineral 

 system, which should indeed depend entirely upon the natural 

 characters and properties of minerals ; but I wish it to be at the 

 same time chemical, physical, and philosophical. Though it 

 may, and indeed must appear to you a piece of bombast to affirai 

 that it is the first system ever contrived, the assertion is true 

 notwithstanding. I do not choose to pubHsh an account of it 

 till the whole has been put in better order, though it is true at 

 the same time that a considerable part of it has become already, 

 in some measure, known to the public. 



My fundamental maxim is, that individual ininerals (and only 

 crystals are individuals) oxoe their nattiral characters to their 

 chemical constituents. Hence the shape of the crystals, the 

 lustre, the electricity, the degree of hardness, the specific gra- 

 vity, &c. must depend upon the nature of the constituents. But 

 if these conclusions be true, it is obvious that little dependence 

 can be put upon the chemical analyses of minerals, which we 

 already possess. I have, for example, put boracite, tourmaline, 

 anatase, andalusite (with respect to it 1 have been unsuccessful 

 in my attempts to discover an essential ingredient), and axinite, 

 under one family. And as the external characters of these 

 minerals bear a close resemblance to each other, I expect from 

 my theoretic maxim, to which I have given the name oi plasti- 

 cism, to find an equal correspondence in the constituents. I, 

 therefore, conclude, that as boron is an essential constituent of 

 boracite, the same substance must also be an essential constituent of 

 tourmaline, anatase, andalusite, and axinite. The proof that 

 boron is essential to the boracite may be deduced from the prin- 

 ciples of crystallography. 



Lampadius has already found about 16 per cent, of boracic 

 acid in the tourmaline and axinite ; and I now learn from my 

 friend Christian Gmelin that he himself, Berzelius, Arfved- 

 son, and Vogel, have made experiments which confirm this 

 result. 



I have a treatise upon the family of schorls quite ready, and 

 I shall make it known as soon as I can procure a good draughts- 



* Translated from Gilbert'^ Aniiuleo, Ix. 211. 



