408 Scientific Intelligences-Mineralogy . 



principally from the fissures ; and the smoke, much thinner than that 

 from the walls of the crater, appeared to be composed of nearly pure 

 steam. Towards the northern edge of the bottom, a black cone, pierced 

 with two mouths, almost diametrically opposite to each other, rose to a 

 height of from 2b to 30 yards above the liquid lava. From each of 

 these mouths a thick column of smoke and jets of melted matter con- 

 tinually issued ; the column of smoke was traversed by an incandescent 

 mass, projected into the air, which soon fell back again in a shower of fire. 

 At intervals of 30 seconds, a dull noise was heard in the interior of the 

 cone, and immediately a sheet of melted matter arose with a loud de- 

 tonation, from one or other of the mouths alternately ; it fell back again 

 in plates round the opening. At the same instant, a jet of fragments 

 of various sizes was projected into the air, and rose to a height of 30 

 or 40 yards. Having descended to the bottom of the crater, the 

 observer, seated at a distance of 50 yards from the southern mouth, 

 could see pretty distinctly what was passing in its interior, to a depth 

 of two yards. The detonations which succeeded the internal noise 

 were stifled, and about as loud as those of a 12-pounder. At the 

 moment when they took place, the opening of the mouth was very red, 

 but it became black immediately after, reddened again at a new de- 

 tonation, and so on successively. The jet of matter accompanied the de- 

 tonation. The smoke which issued from the mouths was red to 3 or 4 

 yards above the opening ; it then became grey. There was no appear- 

 ance of flame, and nothing indicated the combustion of a gas. During 

 all the time the observer remained in the crater, he did not feel the least 

 shock or trembling of the earth. The matter in a state of fusion did 

 not ascend above the mouths ; but at the southwest foot of the cone there 

 was seen a swelling of 2 yards in height and 10 in diameter, covered 

 with a brown cracked crust, under which the burning lava appeared, and 

 from which two small currents issued, advancing so slowly towards the 

 west, that it was impossible to perceive their movements with the eye. — 

 L'lnstitut, No. 547, p. 216. 



MINERALOGY. 



14. The colouring matter of Flint, Carnelian, and Amethyst. — It 

 appears from the experiments of W. Heintz, as stated in Poggendorfl^s 

 Annalen, vol. 60, stiick. iv., p. 527, that flint is coloured by organic 

 matter ; but this is not the case with carnelian and amethyst. The car- 

 nelian appears to be coloured by iron in the state of oxide ; amethyst 

 by iron in the state of acid — the ferric acid. 



15. Composition of the Calc-chrome Garnet, the so called Uwarowite. — 

 According to Herr Erdmann, in Stockholm, this beautiful garnet is com- 

 posed of the following ingredients, — silica, 36.93 ; alumina, 5.68 ; oxide 

 of iron, 1.96 ; oxide of chrome, 21.84 ; lime, 31.63; magnesia, 1.54 ; 

 oxide of copper, a trace ; =99.58. 



16. Beaumontite and Lincolnite identical with Ileulandite. — The 

 Beaumontite of M. Levy, as stated in Silliman's Journal for April 1844, 

 appears to be merely a variety of Heulandite ; and in the same journal 

 we are informed that the Lincolnite of Professor Hitchcock is also a 

 modification of Heulandite. 



