IiUcUi^eitcc and Miscellaneuus Anicies. 151 



tliat which eclipsed the sun. This unexpected occurrence Mr. D. 

 thinks may be turned to advantage, as it seems to show that the 

 reduction of the sun's light, by the intervention of an opaque sub- 

 stance, may enable an observer to see the moon when she is very 

 near the sun. 



There was next read, A letter from Mr. Reeves of Canton, giving 

 an account of a comet seen at sea, Oct. 3d, 4th, 5th, 10th, and 

 30th, 1825. When it was first observed the ship was in lat. 7° 20'N. 

 Long. 1 10° iO' E., the comet was in a line between yj Eridani. and 

 It Ceti, about one-third of the distance from tlie former star. It 

 then passed tt Ceti, advanced toward c Ceii ; and at length on the 

 30th of October was seen so near to a. in the western wing of the 

 Crane, that that star appeared to form the nucleus of the comet. 

 Shortly afterwards the comet entirely disappeared. 



Lastly; A letter Wcis read from M. Garabart to the President, 

 containing new elements of the comet which passed across the sun's 

 disc iii Nov. J 826, with a more precise determination of the mo- 

 ment of its leaving the disc; from which he concludes that both 

 himself and M. Flaugergues of Viviers must have observed the sun 

 before the comet left it. As, however, neither of them saw the 

 comet, the conclusion drawn is, that it was too small or too rare to 

 be visible in that situation. 



XXIX. InlelUgcnce and Miscellaneous Articles. 



ATOMIC WEIGHT OF NICKEL. 



IN consequence of a paragraph contained in Dr. Turner's Ele- 

 ments of Chemistry, p. 418, Dr. Thomson has instituted some 

 new experiments to ascertain the atomic weight of nickel. Pure 

 oxide of nickel was obtained from speiss by the following process: 

 It was first dissolved in a mixture of sulphuric and nitric acids ; the 

 crystals of sulphate obtained by evaporation contained neither 

 arsenic, iron, bismuth nor antimony, but were contaminated by a 

 little copper and cobalt ; the former was precipitated by sulphu- 

 retted hydrogen, and the oxide of nickel, precipitated by carbonate 

 of soda, had chlorine gas passed through it while moist, by which 

 the oxide of nickel was dissolved and that of cobalt left : the mu- 

 riate of nickel thus obtained was then converted into sulphate ; it 

 appeared to be absolutely pure, and by analysis it appeared to be 

 composed of 



1 atom sulphuric acid 5' 



1 atom protoxide of nickel 4-25 



7 atoms water 7*876 



17-126 



Dr. Thomson did not make any experiments on the pero.xidc of 

 nickel; i)ut he concludes, as he has before shown, that the atomic 

 weight of nickel is 'J,-23 ; and he stales his oi)inion to be, ihat ihe 



I'roloNidi' 



