270 ANALYSIS OP MAGNESltB. 



Treated with. c. After having pourect on the residuum of experiment 

 su p uncaci . ^ ^^ ounce of water, sulphuric acid was dropped in, till 

 the residuum ceased to dissolve, even with the assistance of 

 heat. A light brown residuum remained, weighing a quar- 

 ter of a grain, which was oxide of manganese mixed with 

 oxide of iron. The solution being evaporated to dryness, 

 the salt was redissolved in water, and to the last yielded 

 crystals of sulphate of magnesia ; only half a grain of sul- 

 phate of lime was separated, amounting to a third of a grain 

 of carbonate of lime. 

 Muriatic sol u- ^^ fhe solution of experiment a having been treated as 

 ta^ed^by am- ^^ experiment A e, yielded a precipitate, that weighed one 

 jnonia. grain after calcination, and consisted of alumine, containiug 



. traces of the oxides of iron and manganese. 



., " This second variety then contains 



Its component Magnesia .....•••••.•.•••• ^ • v 46-59 



P^"^- Carbonic acid ...» 51 , 



, 4)i , .A-lnmine > 1 



, Oxides of iron and manganese • • 0'25 



Lime •• 0'l6 



Water l 



100. 



It comes very near the first, and differs only in some ac- 

 cidental matters. 



.'W variety, Q^ "Phe variety of magnesite, of which I am now pro- 



•X' ■' ■ ^ ' needing to give the analysis, is perfectly white, more dense 



£ than either of the former, strongly adhesive to the tongye, 



b;.and has a strong earthy smell. It has neither cavities nor 



marblings interiorly, but a few specks of silex. Care was 



taken to analyse only such pieces as contained none of 



'*"" ' ' '^' i^these specks of chalcedonj'^. 



Treated with :' ^' ^^0 grains of this raagnesite, thrown in pieces into 



muriaucacifl. muriatic acid, lost 47 grs, without any heat being applied. 



A gelatinous residuum remained, which would not dissolve, 



though ati excess of acid was added. 



Exposed to a . b. 1 00 grs of pieces of this stone, exposed to a red heat 



TV. leat., |-^j. ^^ hour, left 49 grs* The residuum was a littU reddish, 



and 



