DR. HAYES' ANALYSES. 547 



proving it to be an anhydrous carbonate of magnesia. In diluted acids it hardly effervesces 

 until heat is applied, and then exhibits an astonishing power of resistance to solution at 

 the temperature of ebullition. The powder exposed to heat requires long calcination at 

 bright redness for the expulsion of its carbonic acid, rendering its estimation difficult. 

 This character may have caused an error in previous analyses of serpentine, and led to 

 the conclusion that a hydrate of magnesia forms a part of the composition of all such 

 rocks. 



" II. The following results embrace the averages on compact, nearly white portions [of 

 the veins] : 



Moisture, 0.08 



Water from hydrated minerals, . . . 0.98 



Carbonic acid, . . . . . . .47.16 



Magnesia, 44.24 



Talc, laminse and trace of silicic acid, . . 5.20 



Silicate of alumina, ..... 0.64 



Protoxyd of iron from sil. iron with manganese, 1.53 



99.83 



showing the influence of a small admixture of the included minerals. 



" III. In the following results, the average of the whole rock as quarried [in Roxbury] 



is given the dark greenish-black, light-green and white colors intermixed. 100 parts 



divide into 



Moisture, 0.40 



Carbonate of magnesia, . . . 38.00 

 Included minerals, . . . .61.60 



100.00 

 "61.60 of the various minerals forming the base of the compound rock, consisted of 



Combined water, ...... 6.44 



Silicic acid, ....... 36.92 



Magnesia, ....... 10.52 



Protoxyd manganese and proto-peroxyd of iron, 4.80 



Alumina, ....... 2.06 



Chrome iron, 0.63 



61.37 



" The basis rock, thus proved to be the hydrated ingredient, is an indefinite mixture of 

 so-called serpentine. It is however easily resolved into greenish-white talc, asbestus in 

 various forms, rarely actinolite, ordinary slate as silicate of alumina and iron, constituting 

 an aggregate. But the most remarkable fact is, the entire absence of compounds of lime. 



" In view of this chemical composition and its physical characters, I propose that this 

 rock, quarried for ornamental purposes, be hereafter called serpentine marble." 



Dr. Charles T. Jackson, of Boston, instituted a comparison between the American and 

 European Verd-antiques, and communicated the results to the Boston Society of Natural 

 History, February 20, 1856. We quote from it the following : 



