the Able Haiiy's Theories of Crystallography . 171 



cording to the observations made by Hauy, contained sub- 

 stances similar to the emerald ; I have in that point of view" 

 made a new analysis of this latter stone :" and the former 

 analysis was immediately corrected, and the 29 parts of 

 aiumine became 16* parts of alumine and 13 of a new earth'. 

 I hope, sir, it is no* too much to say that, on this occasion, 

 a new earth was discovered, if not by, at least in consequence 

 of, a geometrical analysis. 



But to return to our subject. The abbe makes a distinction 

 between the integrant particle and the primitive form. The 

 former, as I have said, is that last particle, which, pre- 

 serving an exact proportion of the component parts, contains 

 the least number of those parts ; it is the last term of mine-- 

 ralogical analysis. The primitive form, on the contrary, is its 

 first result, and, retaining the exact proportion of the com- 

 ponent parts, contains the greatest number of those parts. It 

 is easy to see, in the case above mentioned of the phosphate 

 of lime, that the hexaedral prism will be the primitive form, 

 precisely for the reasons adduced to show that it is not the 

 integrant particle. Though the Abbe does not decidedly 

 define the integrant particle, as containing the minimum of 

 space under the maximum of surface, and the primitive form 

 as containing the maximum of space under the 7nhiimum 

 of surface, the inclination of the intersecting planes being 

 the same ; nevertheless he makes a remark that authorizes 

 the above definitions (which, sir, you will observe, are mine, 

 lest any fault be found with them). He says the dodecae- 

 dron with rhomboidal faces, which is the primitive form of 

 the garnet (grenat), contains the maximum of space under 

 the minimum of surface; and if it be cut into two equal and 

 similar parts, it will present the same form as the bottom 

 of the cell of the honey-comb, which has the similar pro- 



P ert > % 



An objection might be taken on the cuivre pyriteux and 



the cuivre gris, or the yellow and gray copper ore of Kirwan, 

 the Abbe mentioning the regular tetraedron as their primi* 

 tive form, and not the octaedron as in other cases. The 

 reason may be, that all the crystalline forms of these sub- 

 stances which he describes are slight modifications of the 

 regular tetraedron. 



"The primitive forms hitherto observed/" says the Abbe 

 Haiiy, " are reduced to 6 ; the parallclopipedon, the octae*- 

 xlron, the tetraedron, the regular hexaedral prism, the do- 

 •decaedron bounded by rhombs all equal and similar, and the 

 dodeeaedron with triangular faces, and formed by two right 

 pyramids united base to base." 



N4 He 



