314 Intelligence and Miscellaneous Articles. 



On the 5th a larger portion of the tail was visible, and it was evidently 

 higher than the evening before ; clouds, however, again hung over the head 

 until it set. 



On the 6th the sky was free from clouds, and the comet presented a 

 most magnificent appearance. Observations of it in Right Ascension and 

 North Polar Distance were obtained this evening with the equatoreal ; but 

 from the excitement at first view of so splendid an object, together with 

 the confusion caused by a number of visitors at the Observatory, I do not 

 consider them entitled to much confidence, especially those in North Polar 

 Distance. The length of the tail I measured roughly with a sextant, by 

 bringing down the image of a star which happened to be situated near the 

 faint end of it, into contact with the head, and made it to be about ,36° ; 

 but from a much better measurement made in the same way on the 13th, 

 this was probably too small. The nucleus of the head (seen through the 

 75-feet telescope) presented rather a well-defined planet-like disc, the 

 diameter of which I estimated to be about 12", and that of the nebulosity 

 surrounding it at about 45". The tail had a dark appearance along its axis 

 as if hollow,- and at about half-way from the head, it even appeared to 

 separate slightly into two parts, the upper one being rather longer than 

 the other. 



On the 13th, after the observations for position, I introduced a parallel 

 wire micrometer, with a view to measure the diameter of the bright part, 

 or disc, of the head, and, by a pretty fair measure, made it to be 11". The 

 nebulosity about it I estimated to be about four times the diameter of the 

 bright part. The length of the tail, measured carefully with a sextant, I 

 found to be 45°; its breadth, at one-third its length from the head, 33', 

 and at two-thirds its length, 60'. 



Since the 19th the weather has been unfavourable, and no observations 

 have been obtainable. The comet appears to be getting somewhat fainter 

 than it was on the evenings of the 6th and 8th, but only slightly, and very 

 slowly so. 



Trevandrum Observatory, March 22, 1843. John Caldecott. 



A second letter has been received from Mr. Caldecott, dated April 

 21, giving the following additional observation : — 



h m s h m s 



March 26. 7 3 3635 Trev. M.T. R. A. = 3 38 7"3. 

 N.P.D. = 97° 39' 12". 

 From the observations of the 8th, 13th, and 18th of March, Mr. 

 Caldecott computed the parabolic elements, which are as follow : — 



Long, of the Ascending Node 3° 7' 



Inclination 35 3 



Long, of the Perihelion 279 6 



Perihelion Distance 0-0048 



Time of Perihelion Passage, Feb. 27'654, Trevandrum mean time. 

 Motion retrograde. 



XXXVII. Intelligence and Miscellaneous Articles. 



ON THE NON-PRECIPITATION OF LEAD FROM SOLUTION IN 

 SULPHURIC ACID BY HYDROSULPHURIC ACID. BY. M. DUPAS- 

 QUIER. 



WHEN a current of hydrosulphuric acid is passed through, or an 

 aqueous solution of this acid gas is poured into, commercial 

 sulphuric acid diluted with an equal weight of water, only tin and 



