ALUMINOUS CHALYBEATE SPRING IN I. OF WIGHT. 85 



such practical observations on their general properties, as 

 may serve to show the importance of a more particular at- 

 tention to this subject, than has hitherto been thought ne- 

 cessary in practical mechanics. 



E. LYDIATT. 



London, April the 15th t 1812. 



II. 



A Chemical Account of an Aluminous Chalybeate Spring in 

 the Isle of Wight. By Alexander Marcet, M. D. 

 F. R. S. one of the Physicians to Guy's Hospital, and 

 Member of the Geological Society. 



(Concluded from p. 66. ) 



Sect. IX. Sulphate of Ahminc. 



1. Ji? IFTV grains of residue f were boiled in two successive Residue treat- 

 ,. . . „ ^. . i » • . tTiiT '. \ i i ed with caustic 



lixivia or caustic potash (as in secli VI 11, 1), so as to take up poUs i, 



all the alumine present; the residue was separated and well 

 washed, and the washings were added to the alkaline solu- 

 tion. The clear liquor had a brownish colour, and on 

 being tried with muriatic acid and prussiate of potash, a 

 blue tinge was produced, which appeared to have arisen 

 from a few particles of oxide of iron, which were suspended 

 in the lixivium rather than actually dissolved; for the solu* 

 tion being left at rest for some time, these particles sub- 

 sided. 



2. To the clear alkaline solution muriate of ammonia and predpitat- 



was added, till no farther precipitate took place; the pre- e ? b7 rnuriate 

 r r * ' " or ammonia, 



cipitaie was edulcorated and collected in a falter., It was 



•f- These fifty grains had been previously boiled in neutral carbonate ' 

 of ammonia, in order to separate the magnesia, as will be detailed 

 hereafter. The previous intervention of a carbonated alkali renders 

 the subsequent application of caustic potash for the separation of 

 the alumine more unexceptionable, as a solution of caustic potash 

 might redissolre a small portion of the lime, if it were not previously 

 carbonated* 



white 



