The lime was converted, by means of sulphuric acid, into gypsum, and thus severed from its associate. The relative proportions of the ingredients are as follows.
| Silica | 62. | 2 |
| Lime | 14. | 1 |
| Magnesia | 12. | 9 |
| Oxide of Iron | 5. | 9 |
| Water | 1. | |
| Of Manganese and Soda, a trace | ||
| loss | 3. | 9 |
| ───── | ||
| 100. | 0 | |
