On Crystallography. 67 



one hand, it is constantly the same being which merely passes 

 to other dimensions ; on the other hand, it is always a new- 

 being in proportion to what it acquires. 



We shall have an idea of the formation and increase of 

 minerals, if, after having dissolved common salt in water, 

 we observe what passes while the water is evaporated : we 

 shall see small masses of salt deposited on the surface of the 

 water, or upon the sides of the vessel which contains it, and 

 increase in proportion as they attract new particles. In this 

 case the figure of these mass'es is out of tlie question, and 

 we confine ourselves to considering generally the method in 

 which they arc formed. 



The molecules- of stones, metals, &c., may for a time be 

 suspended in a liquid. When this liquid afterwards aban- 

 dons them successively, from whatever cause, they re-unite, 

 in obedience to their mutual affinity, and produce solid 

 masses*. 



These molecules, of which the mineral Is the aggregate, are 

 imperceptible to our eyes, even with the assistance of the 

 best optical instruments. But we caimot doubt that tiiey 

 have determinate forms, and that they are not similar iu 

 every species of mineral. We are even led to adopt this 

 idea, by observations made upon a great number of mine- 

 rals. 



Let us continue to take as an example the salt already 

 mentioned. If we cautiously strike a portion of this salt, 

 we sec it divided into fragments of a cubical form ; and on 

 continuing the division, we shall have cubes successively 

 smaller, until they are no longer visible without the micro- 

 scope. 



On the other hand chemistry, by analysing the salt in 

 question, proves that it is composed of two diflerent prin- 

 ciples ; one of which is an acid called muriatic acid, and the 

 otljcr an alkali called soda. These two principles are com- 



* The .iclidii of caloric, orhoat, supplies the place of liquids in the forma- 

 tion of ceruiii minerals ; when the niolocules of the latter, which its intcrpo- 

 iition at first kcc|w sepafttcd, afterwards acquire, upon its rttieat, the )ib«rt/ 

 ot reuniting by virtue of their reciprocal afRfiity. 



E 2 bined 



