5. Aurora Borealis seen in the Day-time at Canonmills.
6. Aurora Borealis in Siberia.
7. On the Presence of Ammonia in Argillaceous Minerals.
It was now suspected that all mineral substances, emitting an argillaceous odour, contained ammonia; a great number of specimens were tried, being moistened with solution of caustic potash, and examined by litmus paper. In no case was ammonia absent, and with common clay it continued to be evolved for more than two days. Amongst the substances tried, were pipe clay, other clays, numerous gypsums, Paris plaster, steatite, &c. The antiquity of the mineral seemed to have no relation to the ammonia.
M. Bouis concludes that, in all cases, the argillaceous smell of minerals is connected with, and dependent upon, the presence of ammonia, the latter being the vehicle of this particular odour.—Annales de Chimie, xxxv. 333. [p490]
8. Composition of Apatite.
| S. G. | Chlo. Calc. | Fluor. Calc. | |
|---|---|---|---|
| Apatite from Suarum in Norway | 3.174 | 4.280 | 4.590 |
| Cabo de Gota in Spain | 3.235 | 0.885 | 7.049 |
| Arendal | 3.194 | 0.801 | 7.010 |
| Greiner in the Tyrol | 3.175 | 0.150 | 7.690 |
| Faldigl, ditto | 3.166 | 0.100 | 7.620 |
| St. Gothard | 3.197 | trace | 7.690 |
| Ehrenfriedersdorf | 3.211 | trace | 7.690 |
| Annales de Chimie. | |||