140 ULTRAMARINE. 



All these crystals and the remaining liquor afforded by 

 means of ammonia 6*85 of dry alumine, and 9*60 of sul- 

 phate of soda fused by fire. 

 These more We found by other experiments^ that the alumine and 

 * h "i 1^"^" soda were commonly in greater quantity than the action 

 dicated. of sulphuric ac' J indicated. 



By passing oxigenated muriatic acid gas into water in 

 which 20 grammes of ultramarine were kept in constant 

 agitation, 18*48 were dissolved. The remaining 1*52 had 

 SUex. aJl the characters of silox. From the solution we ob- 



tained 4'6 of dry alumine, as much muriate of soda as 

 contained about 4 grammes of alkali, and a portion of 

 sulphate of barytes containing 6 tenths of a gramme of 

 sulphur, supposing it to be composed of 33 per cent, of 

 sulphuric acid, and this acid of 5i per cent, of sulphur. 

 'JPhe quantity of silex was not well ascertained. 



If 5 grammes of ultramarine be fused with 20 grammes 

 of potash, and the compound be treated with alcohol, 

 its weight is diminished one gramme, and the alcohol 

 contains very little silex and alumine. This loss is evi- 

 dently owing to the soda of the ultramarine, which quits 

 the other principles, because their combination has been 

 broken by the action of the potash in the fire. 



On treating ultramarine with carbonated soda, we ob- 

 tained from 10 grammes 3*3 of silex, possessing all its 

 peculiar characters in a manner less equivocal than was 

 sometimes the case, when it had been procured from 

 ultramarine treated by acids or caustic alkalis. We had 

 Mixture of supposed, that this was owing to a mixture of some fo- 

 substancc s i^s- reign substance, but we were unable to detect any. To 

 pected ascertain this silex we had employed the ordinary means ; 



and among the rest volatilization by the fluoric acid, 

 • which deposited a jelly in the water it was passed 

 through. 

 Results. Thus the ultramarine afforded on decomposition silex, 



alumine, soda, and sulphur. 



Theory of the If ^e bear in mind, that this valuable substance, as 

 process of ex- ' ^ . . ' 



traction. famished by the process of its extraction, contams olea- 



ginous particles ; that soda is one of its constituent prin- 

 ciples; that the first waters used for washing away the 

 ultramarine from the cement, with which its ore had been 

 1 incorporated, 



