Analyses of Limestones.
| I.—Spirorbis Limestone from Ardwick. | II.—Limestone from the Roman Foundations, Castlefield. | ||
| Calcium carbonate | 95.5 | 96.0 | per cent. |
| Calcium sulphate | 0.08 | 0.09 | ,, |
| Oxide of iron and alumina | 0.21 | 0.44 | ,, |
| Insoluble in acid | 0.84 | 0.60 | ,, |
| Magnesia | none | trace | |
| Organic matter | 0.50 | 0.20 | ,, |
| Phosphates | traces | traces | |
| Combined water, moisture, alkalies, &c. | 2.87 | 2.67 | ,, |
Bricks.—Various sizes of bricks have been discovered by me at Castlefield. They are very rarely complete. I obtained fragments, about 5 inches thick, of bright red colour, and another much thicker yet and perforated. A complete brick, 14 by 7 by 4 inches, weighing about 40 lb., from the same place, is now in my possession.
Flanged Tiles.—I have parts, 7 inches to 10 inches wide, 1 inch thick. There are various types at the station with flanges 1½, 2, 2⅛, 2¼, and 2½ inches high, differently bevelled and channelled, the width of the flanges varying from ⅞ inch to 1⅜ inches.
Whitaker found some entire tiles, measuring 16¾ by 11¼ by 1½ inches.
Howarth mentions some tubes 12 or 14 inches square and 1½ inches thick.
Flanged tiles generally measure 15¾ by 12 by 2¼ inches, and plain tiles 16 by 10½ by 1½ inches.
At Melandra tiles have recently been found 8 inches square and 2 inches thick.
