SULrHURET OF LEAD, COPPER, AND ANTIMONY. 311 



forming the integrant molecule, which is the immediate 



result of tins combination, differs then in no respect from 



that, which afterward unites the integrant molecules. Now 



it is very easy to conceive, and even to adduce a number of 



instances of the formation of a crystal of any determinate 



figure (representing the integrant molecule of a compound 



substance) that shall be composed of the intimate union of 



three, four, or even more crystals of dilFerent forms, which 



in this case would represent the molecules of the substances 



fhat compose it ; and which would enter into the composition 



of the crystal in equal numbers, or, which is more commonly 



the case, in unequal numbers. It is indeed to the property, Particles unite 



which the molecules of minerals have, of uniting intimately to form . se cond- 



J ary particles of 



■with each other, so as to produce a new molecule of a a different 



determinate figure, that I attribute in part the formation of fi S ur f mche - 



& ' * micalcom- 



those minerals, which are commonly said to be the effect of binations. 



chemical combination. Every combination of the sub- 

 stances of which a mineral is composed seems to me to re- 

 quire, that the form of the molecules of each shall bear 

 such a relation to those of the rest, that their faces may 

 respectively coincide, so as to produce collectively a mole- 

 cule, the form of which shall be at once determiuate and 

 invariable. It is this relation between the several component 

 molecules, which in all probability determines their action 

 upon each other, known by the name of "attraction of 

 composition;" or which is at least a principal cause of this. 

 Upon the same-principle we may account for the proportion 

 of the several substances, which must necessarily vary, 

 according to the number of these molecules, the forms of 

 which are different, and the mode in which they arrange 

 themselves, so as to produce a new molecule, the form of 

 which shall be determinate. When the molecules are wholly 

 dissimilar, and there is no relation whatever between their 

 faces, it is not possible for them to combine, so as to 

 generate a new substance properly so called and capable of 

 crystallization. 



The real existence of these triple and greater combi- Gypsum there- 

 nations 1 is farther demonstrated by facts. We know, ftrJ^jJlK!! 

 instance, that there exists a substance which differs from 

 gypsum, or the combination of lime with sulphuric acid ana 

 Y 2 water. 



