Sulphate contained in a pint of the Water.
| sulph. of baryt, ignited | |||
| Sulphat of iron (§ VIII. 9) 41,4 grs. crystallized | = | 31,8 | grs. [1] |
| Sulphat of alumine (§ IX. 5) 3,8 grs. ignited alumine | = | 17,7 | ditto[2] |
| Sulphat of lime (§ X. 4) 10,17 grs. dried at 160° | = | 13,9 | ditto[3] |
| Sulphat of magnesia (§ XII. 2) 3,63 grs. crystallized | = | 4,0 | ditto[4] |
| Sulphat of soda (§ XIV. 7) 16,0 grs. crystallized | = | 11,6 | ditto[5] |
| ─── | |||
| Total amount of the sulphat of barytes | 79,0 | grs. | |
- ↑ These proportions were deduced from the following experiment : 50 grains of crystallized green sulphat of iron were dissolved in water, and nitrat of barytes was added as long as any precipitate took place. The sulphat of barytes after being carefully edulcorated and heated to redness in a platina crucible, weighed 38,5 grs. Therefore 50 : 38,5 :: 41,4 : 31.
- ↑ It may be recollected that 3,8 grs. of ignited alumine, would, according to the proportion before stated (§ IX. 5,) correspond to 31,6 of crystallized alum. I found by a direct experiment that 100 grs. of regular octohedral crystals of alum formed by gradual deposition from a saturated solution of common alum, being dissolved in water and precipitated by muriat of barytes, produced 88,2 grs. of ignited sulphat of barytes; so that the 31,6 grs. of alum would correspond to 27,8 grs. of the barytic sulphat. This, however, could not be an accurate estimate of the real quantity of sulphuric acid, since the sulphat 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 pore sulphat of alumine, I made the following attempt. A quantity of alumine (which had been prepared by precipitation from alum, re dissolution in muriatic acid, and second precipitation by carbonat of ammonia, and appeared to contain no impurity except a vestige of muriatic acid), was dissolve din sulphuric acid, and the solution evaporated to siccity. When reduced to the consistence o fa thick syrup, and allowed to cool, the saline mass congealed into a hard whitish deliquescent cake, capable of being pulverised. This was redisolved and re-evaporated four successive times, and the last time was made red-hot, in order to expel the excess of sulphuric mid which always appeared to prevail. By this last operation a portion of the salt was decomposed and rendered insoluble in water, in spite of which the remainder still exhibited signs of acidity. The clear solution of this mass being divided into two equal portions, one of which was precipitated by succinat of ammonia, and the other by nitrat of basytes, yielded 4,5 gra. of ignited alumine for 21 grs. of ignited sulphat of barytes. From which it may be inferred, that the 8,8 grs. of ignited alumina found in a pint of the water, were combined with a quantity of acid equal to 17,7 grs. of ignited sulphat of barytes. But it is assumed in this computation that the artificial sulphat of alumina subjected to analysis, was in the same state of combination as that which exists in the water, a supposition which may not be strictly accurate.
- ↑ The quantity of sulphat of barytes produced by the precipitation of a given quanttity of sulphat of lime, was ascertained in the following manner: some pulverized crystals of native selenite, apparently perfectly pure, were dissolved in water and afterwards slowly precipitated by evaporation. The object of this previous operation was to obtain the sulphat of lime in a state more lit for subsequent re-dissolution. Fifteen grains of this selenitic residue were dissolved in water, slightly acidulated by muriatic acid, in order to supersede the necessity of using a large quantity of water; and the solution, after being neutralized by pure ammonia, was precipitated by muriat of barytes. The sulphat of barytes thus obtained, weighed, after careful edulcoration and ignition in a platina crucible, 26,75 grs. which is equivalent to 175,6 grs of harytes for 100 grs. of ignited sulphat of lime.
- ↑ According to Dr. Henry 100 grs. of crystallized sulphat of magnesia give 111 grs. of ignited sulphat of barytes. See Philos. Trans. 1810, p. 114.
- ↑ These proportions were deduced from the following experiment: 40 grs. of crystallized sulphat of soda, being dissolved in water and precipitated by nitrat of barytes, the sulphat of barytes, well edulcorated and ignited, weighed 29,1 grs.
