gg ALUMINOUS CHALYBEATE SPRING IN I. OP WIGHT. 



I shall now recapitulate the several sulphates discovered in 

 the water, and from the quantities of each compute the 

 quantities of barytic sulphate, which would result from their 

 decomposition, 

 the water. Sulphates contained in a pint of the Water. 



Sulph. of baryt. 

 ignited. 

 Sulphate of iron (§VIII, 6) 41 *4 grs. crystallized zz 31-8 grs.* 

 Sulph. of alumiue(§ IX, 5,) 3*8 grs. ign. alumine zz 177 do. t 

 Sulph. of lime (§ X, 3) 10-17 grs. dried at l6o° = 13-9 do. J 

 Sulph. of magnesia (§ XII, 2) 3-63 grs. crystal. — 4*0 do. If 

 Sulph. of soda (§ XIV, 7) l6'0 grs. crystallized zz ] 1 -6 do. § 



Total amount of the sulphate of barytes • • • -790 grs. 



* These proportions were deduced from the following experiment: 

 50 grains of crystallized green sulphate of iron were dissolved in water, 

 and nitrate of barytes was added as long as any precipitate took place. 

 The sulphate of barytes, after being carefully edulcorated and heated 

 to redness in a platina crucible, weighed 3S.5 grs. Therefore 

 50 : 88 5 : : 41*4 : 31 8. 

 Proportions of f It may be recollected that 3'8 grs. of ignited alumine would, ac- 

 »tiaandbasein cor( j m g to the proportion before stated (Sect IX, 5,) correspond to 

 of alumine" 3i ^ °^ c, 7 Sia 'hzed alum. I found by a direct experiment, that 100 

 grs. of regular octohedral crystals of alum formed by gradual deposition 

 from a staturated solution of common alum, being dissolved in water 

 and precipitated by muriate of barytes, produced S8 - 2 grs. of ignited 

 sulphate of barytes; so that the 3i'6 grs. of alum would correspond 

 to 27*8 grs. of the barytic sulphate. This, however, could not be an 

 accurate estimate of the real quantity of sulphuric ac,id, since the 

 sulphate of alumine does not exist in the water in the state of alum. 



With a view to learn the proportions of acid and base in pure sulphate 

 of alumine, I made the following attempt. A quantity of alumine 

 (which had been prepared by precipitation from alum, redissolution 

 in muriatic acid, and second precipitation by carbonate of ammonia, 

 and appeared to contain no impurity except a vestige of muriatic acid), 

 was dissolved in sulphuric acid, and the solution evaporated to siccity. 

 When reduced to the consistence of a thick sirup, and allowed to 

 cool, the saline mass congealed into a hard wTtitish deliquescent cake, 

 capable of being pulverized. This was redissolvcd and reevaporated 

 four successive times, and the last time was made redhot, in ordrr to 

 txpel the excess of sulphuric acid, which always appeared to prevail. 

 By this last operation a portion of the salt was decomposed and ren- 

 dered insoluble in water, in spite of which the remainder still exhibited 

 signs of acidity. The clear solution of this mass buing divided into 



