Intelligence and Miscellaneous Articles. 317 



■west, and a much larger circle, well-defined, of a pale white, having 

 the sun in the south-west of its circumference. 



The interior of the halo, except the sun's disc, was of a much 

 darker colour than the surrounding atmosphere. 



The centre of the larger halo was very near, if not in the zenith. 



CRYSTALLIZATION OF OCTAHEDRAL IODIDE OF POTASSIUM. 

 BY M. BOUCHARDAT. 



By evaporating a saline solution containing iodine, iodide of po- 

 tassium and acetic aether, M. Bouchardat obtained light yellow- 

 coloured semitransparent octahedral crystals. These crystals, when 

 heated in a tube, yielded traces of iodine, and the fused residue con- 

 sisted entirely of iodide of potassium ; similar crystals were pro- 

 duced from a solution of biniodide of potassium by spontaneous eva- 

 poration ; in order to obtain them there must be a great excess of 

 iodine in the solution, although they do not contain l-1000dth of 

 their weight of free iodine ; but it is certainly curious to observe the 

 iodide of potassium lose its usual form owing to the presence of so 

 small and indefinite a portion of iodine. — Journal do Pharm. et de 

 Chim., Juillet 1843. 



ON THE PRESENCE OF THE SULPHATE OF TIN IN THE SUL- 

 PHURIC ACID OF COMMERCE. BY M. DUPASQUIER. 



It is generally known that the sulphuric acids of commerce con- 

 tain lead, iron, and frequently arsenic ; but I am not aware that the 

 existence of tin in them has hitherto been noticed. Nevertheless this 

 metal may be obtained, and in somewhat considerable quantity, 

 from most of the commercial acids ; and it will not be useless to be 

 aware of this circumstance, which may have some influence in many 

 operations, especially in those of dyeing, which should be taken 

 into consideration. 



I found sulphate of tin in all the acids which I examined while 

 engaged in the researches which I have published on the arsenife- 

 rous sulphuric acids in the following manner : — In order to precipi- 

 tate the arsenic of these acids, I diluted them with twice or six 

 times their weight of water, and passed a current of sulphuretted 

 hydrogen through them, which gave rise to a yellowish-brown pre- 

 cipitate when the acid contained arsenic ; this precipitate was less 

 considerable, and of a darker brown when the acid was not 

 arseniferous. 



Thinking that sulphuret of lead might have been formed, and that 

 the brown colouring of the sulphuret of arsenic should be attributed 

 to that compound, I treated the precipitates obtained by the action 

 of sulphuretted hydrogen on the sulphuric acids with nitric acid, 

 and I constantly obtained a white residue, insoluble in water, soluble 

 in aqua regia, which solution presented all the characters of the 

 nitro-muriate of tin. With respect to the solution effected by the 

 nitric acid, I found it to be arsenic acid when this sulphuret of tin 



