154 PHILOSOPHICAL TRANSACTIONS. [aNNO 1792. 



washed and dried, 170 grains: this having been again saturated with diluted 

 vitriolic acid, afforded 9 10 grs. of pure crystallized vitriolated magnesia. The 

 solution remaining after the separation of the magnesia having been duly eva- 

 porated, yielded 282 grs. of crystallized Glauber salts, exclusive of what had been 

 formed by the above-mentioned admixture of the natron. 



Exper. 4. The 188 grs. of remaining earth, mentioned in the preceding exper. 

 were put into aqua regia, and the solution mentioned in the first exper. as marked 

 (a), was added. This mixture having been well heated, and again suffered to 

 cool, was put on some filtering paper ; and what remained on this, having been 

 well washed with diluted spirit of wine, and dried, weighed 1 12 grs. The filtered 

 solution was then gently evaporated, during which it deposited 6 grs. of selenite; 

 a sufficiency of phlogisticated alkali was now added, to separate the iron ; 25 grs. 

 were required, and the dried blue precipitate weighed 15 grs. It is to be ob- 

 served, that the phlogisticated alkali contained, in 25 grs., 4^ grs. of the calx of 

 iron. The above blue precipitate was put into a small crucible, and kept for a 

 proper time in a red heat, when it left 7t g^s- of calx of iron, which was attracted 

 by the magnet ; if from this be deducted the 4-l grs. contained in the alkali, there 

 will remain 3 grs. which had been contained in the water. 



Exper. 5. The solution, from which the iron had been precipitated, was eva- 

 porated, and mixed with vitriolic acid, and diluted spirit of wine, when 72 grs. of 

 selenite were separated : these 72 grs. of selenite having been boiled with mineral 

 alkali, yielded 24 grs. of calcareous earth. 



Exper. 6. The remainder of the solution from which the calcareous earth had, 

 by means of the vitriolic acid, been separated in the form of selenite, yielded, by 

 adding mineral alkali, Tl\ grs. more of magnesia. All the selenite obtained was 

 boiled in 1200 times its weight of water, in which it was completely dissolved, no 

 siliceous earth being left. As a proof that the process had been properly con- 

 ducted, Mr. S. saturated both the obtained earths with diluted vitriolic acid ; 

 when the first again afforded selenite, and the other vitriolated magnesia. 



Summary of the constituent parts of the Kilburn Water, in 24 pounds. 



Fixed air 84 cubic inches. 



Hepatic air near 36' 



Vitriolated magnesia 91O grains, equal to Jij Jiiss apothecaries weight. 



Vitriolated natron 282 gr. = 5V. lij grs. 



Muriated natron 60 gr. = 7,0 gr. 



Selenite 130 gr. = 5 ij xlij gr. 



Muriated magnesia 128 gr. = 5ij xl gr. 



calcareous eartli 6 gr. = 7g gr. 



Aerated magnesia 12^ gr. = 15 gr. 



— — — calcareous earth 24 gr. = 30 gr. 



Calx of iron 3t S""' ~ * S""- 



Resinous matter ..., 6 gr. = 7 ^ gr. 



Sum 156l| grs. equal to medicinal weight 4 oz. dr. and 32 grs. 



