Translations and abstracts from the French. 26 1 



pears to have been noticed by others. Carbonate of hme 

 rhomboid^)!, hexagonal and metastatique, Iceland spar, of 

 various modifications ; lamellar, saccharoidal, fibrous, com- 

 pact and stalactitic spar, varied in the extremes, from 2.7041 

 to 2.7234. Pure arragonite, crystallized, fibrous and fibro- 

 compact, varied from 2.9467 to 2.9053 ; coralloid trans- 

 lucid, 2.8321 ; opake, 2.7647. Malachite, pure, from 3.5907 

 to 3.3496. Carbonate of lead, from 6.7293 to 6.7102. Sul- 

 phate of lime, from 2.3257, in small crystals, to 2.2615, nivi- 

 form. Sulphate of strontian, from 3.9593 to 3.9297. Sul- 

 phate of lead, from 7.7593 to 7.7398. Quartz, pure, from 

 2.6541 to 2.6354. It results from the researches of M. Beu- 

 dant, that small crystals always have the greatest specific 

 gravity, and hence it follows that it is in small crystals we are 

 to look for the greatest homogeneity, as well as what has 

 been long known, the greatest perfection in form. 



The lowest specific gravity is always found in the fibrous 

 or epigene varieties. Hence it appears that the difference 

 of specific gravity in the same substance, depends on the 

 manner in which the rudimental crystals are aggregated to 

 form masses more or less considerable, and M. Beudant has 

 accordingly found that when reduced to powder, all the 

 varieties of the same substance present what may be con- 

 sidered as the same absolute specific gravity, the differences 

 being such only as come with the limits of possible errors 

 in the operation. He therefore recommends that the abso- 

 lute specific gravity of the substance be taken, as a minera- 

 logical character, by reducing it to powder, and allowing it 

 to imbibe the liquid which serves as a common measure. 



When thus treated, the following is given as the specific 

 gravity of the eight following substances, which is constant 

 in all the varieties, and which may serve to distinguish them 

 when pure. 



Carbonate of lime — rhomboidal, - 2.7231 



Arragonite, 2.9466 



Malachite, 3.5904 , 



Carbonate of lead, - - - - 6.7290 

 Sulphate of lime, .... 2.3316 

 Sulphate of strontian, - - - 2.9592 



Sulphuret of lead, ... - 7.7592 



Quartz, 2.6540 



Idenu 



