198 Proceedings of the Royal Society ofEdmlmrgh. 



tion being affected by some degree of local attraction, from the con- 

 fined spaces in which the experiments were made. 



The magnetic intensity, as deduced from the time of 300 vibra- 

 tions in the reporter's experiments with the Society's needles, is, 

 with Hansteen's cylindrical needle^ 



At Liverpool, mean of three series = 798''. 21 

 At Manchester, from one series . = 798.82 



With Dollond's flat needle, 



At lAverpool, mean of three series = 1052.83 

 At Manchester, from one series . =1051.76 



The reporter also stated, that the magnetic dip at Liverpool, as 

 ascertained by several experiments made there by Lieutenant Allen, 

 R. N. and himself, with a needle furnished by the Board of Admi- 

 ralty, for the late expedition up the Niger, is = 72° 2' 24". 



The experiments on the dip, as well as two other series on mag- 

 netic intensity with a horizontal needle belonging also to the Admi- 

 ralty, were made on the same spot as those with the Society's needles, 

 viz. an open space in the Botanic Garden at Liverpool. 



3. Description and Analysis of a Mineral from Faroe, not be- 

 fore examined. By Arthur Connell, Esq. 



The mineral in question was put into the author's hands by Mr 

 Rose, mineral-dealer of this city, as a substance supposed to be a 

 variety of mesotype. Mr Rose obtained it from Count Vargas Bede- 

 mar of Copenhagen, who had brought it from Faroe. 



It has a pure white colour, with some opalescence and translucence, 

 a glistening vitreous lustre, and somewhat greater hardness than fluor. 

 Its texture is imperfectly fibrous ; but the fibres in some places diverge 

 with considerable regularity, shewing an approach to a crystalline 

 structure. The specific gravity is 2.362 ; it is remarkably tough and 

 difiicultly frangible, so as to require much time and labour to separate 

 a mass of it into smaller fragments. 



It gives off water at a red heat ; and is fusible per se before the blow- 

 pipe only on the edges, without any swelling up. With soda it fuses 

 with effervescence into a semi-transparent glass ; with borax and 

 salt of phosphorus, gives colourless glasses ; and, with nitrate of co- 

 balt, presents no alumina reaction. It gelatinizes readily with muria- 

 tic acid when reduced to powder. The analysis was effected by 

 this reagent. After separating silica, the metallic oxides were thrown 

 down by ammonia, and the lime by carbonate of ammonia. The al- 

 calies were separated from one another by chloride of platinum, and 

 the water was determined by ignition. Its composition is as follows : 



Silica 57.69 



Lime - - . . _ 26.83 



Water 14.71 



Soda 44 



Potash .23 



Oxide of Iron 32 



Oxide of Manganese - - - .22 



100.44 



