YORKSHIRE ALUM WORKS. ^5S 



tised, and the quantity of alum produced upon a large scale 

 nearly correspond. 



I know of no experiments, that have been made to ascer- 

 tain the composition of sulphate of alumine, except Berg- 

 man's. I believe Vauquelin has done the same, but as I 

 have not seen his paper, I cannot speak to that effect. Berg- 

 man states the composition 



Sulphuric acid « 50 



Alumine 50 



100 



From a solution of pure sulphate of alumine in water I 

 precipitated the acid, by means of the muriate of barytes 

 added in excess. The precipitate, after having been care- 

 fully washed upon a filter, was exposed to a white heat for 

 some time. The <quantity of acid inferred from the sul- 

 phate of barytes obtained, was 287 grains. 



To an equal quantity of a solution of sulphate of alu- 

 mine, ammonia was added to saturation ; the precipitate, af- 

 ter washing upon a filter, was exposed to a white heat for 

 an hour, and weighed 209 grains. Therefore sulphate ©f 

 alumine is composed of 



Sulphuric acid ........ 57*8 



Alumine 42*2 



100-0 



Analysis of alum. 



Exp. 1. To 10000 grains of a very pure crystal of alum, Ajia5ysi$of sa- 

 dissolved in rain water, was added muriate of barytes, until persulphate of 

 no farther precipitate took place. The sulphate of barytes, potash. 

 after having been well washed upon a filter, was exposed 

 to a white heat for some time, it weighed 3359 grains. 



£xp. 2. To 10000 grains (of a part of the same crystal, 

 as used in the preceding experiment) in solution, was add- 

 ed ammonia, until the precipitation was found to be com- 

 plete. After washing and filtering the alumine, it was ex- 

 posed to the heat of a blast furnace, and found to weigh 

 1096 grains. 



JExp. 



