1818.] Scientific Intelligence. 465 



globules of a metal resembling silver when silica has been fused 

 with borax before the gas blow-pipe, the difficulty of obtaining 

 which is owing to their volatilization almost in the instant of 

 their being formed. A still more remarkable result was obtained 

 in the fusion of apatite; when a globule of metal was obtained, 

 which is now in the possession of Mr. Lunn, of St. John's 

 College, Cambridge. It is not pretended to account for these, 

 phenomena, but merely to state the facts, in the hope that 

 others may confirm and explain tbe.n. 



III. Comet 0/I8II. 



During the course of the last year, M. Schroter, of Lilienthal, 

 has published an account of the comet which appeared in 1811; 

 and by comparing his observations on this comet with those 

 which he made upon that which appeared in 1807, he has been 

 led to form some singular conclusions. The nucleus of the 

 comet of 181 1, the apparent diameter of which was 1' 49", and 

 which, calculating from the distance, must have had a real dia- 

 meter of 10,900 miles, M. Schroter supposes to be composed of a 

 fluid covering a solid mass. In the centre of this nucleus we dis- 

 tinguish a second, which is smaller and more luminous, the 

 apparent diameter of which being 16'97", gives a real diameter 

 of 1,697 geographical miles. This central part was surrounded 

 with a particular kind of atmosphere, upon which many of its 

 most remarkable variations depend. Besides this, it was 

 surrounded by a luminous nebulosity, which always exhibited 

 the same brilliancy in every part of its surface, without any 

 appearance of phases ; from which circumstance he concludes, 

 that this light being always equable, cannot be the effect of 

 any reflection from the solar light. 



Two different parts may be distinguished in the head of this 

 comet : 1 . A spherical nebulosity of a whitish coloured light, 

 which surrounded the exterior nucleus, and which is supposed to 

 depend upon the spontaneous luminousness of the body ; 2. The 

 posterior part opposite to the sun, beyond which was extended 

 the double tail ; this part was separated from the nucleus by a 

 dark interval, equal to half the total diameter of the head of the 

 comet. The apparent diameter of this head was 34' 12", which 

 gives it a real diameter of 2,052,000 geographical miles. 



The greatest apparent length of the tail is 18°, which gives a 

 real length of 131,852,000 geographical miles. M. Schroter 

 conceives that we cannot explain this prodigious extent without 

 admitting that there exists in space around the sun a subiile 

 matter, susceptible of becoming luminous by the combined 

 influence of the sun and the comet. Independent of the force 

 which comets exercise as masses of matter, he conceives that 

 they are endowed with a repulsive and impulsive force, which 

 has some analogy to the electric fluid, and like it acts indifferent 

 directions. 



Vol. XI. N° VI. 2 G 



