394 Intelligence and Miscellaneous Articles. 



with a short four- sided prism interposed between the two pyramids, 

 and the latter of these with various truncations of its angles and 

 edges. The specific gravity of some picked crystals was 6*753. A 

 careful analysis of this tinstone gave as its constituents- 

 Peroxide of tin 95*26 



Peroxide of iron 2*41 



Silica -84 



98-51 



The greater number of the minerals here enumerated are men- 

 tioned by Mr. Weaver in his reports to Government on the district, 

 and which are to be found in the Transactions of the Royal Dublin 

 Society ; but some of them, the author believes, have not been no- 

 ticed before, at least he has seen no published account of the occur- 

 rence in this locality of platina, titanic iron, sulphuret of molybdenum, 

 topaz, zircon, the small manganesian garnets, or augite. Hence it 

 seemed interesting, while noticing these, to collect into a uniform 

 and as far as possible complete list, all the scattered notices of the 

 mineral wealth of this particular district, which are to be found in 

 Mr. Weaver's papers already referred to, and elsewhere. 



The principal point, however, with respect to the examination of 

 these minerals, which appears to merit further and more particular 

 attention, is the fact of the existence of tinstone in such considerable 

 quantity in these auriferous streams ; — a fact which would seem to 

 indicate the probable existence somewhere in the surrounding di- 

 strict, of masses of the ore of this valuable metal of great extent, 

 and possibly forming the continuation, on this side of the Channel, 

 of those vast deposits which have contributed to furnish occupation 

 and support to the inhabitants of Cornwall for more than two thou- 

 sand years. — Transactions of the Geological Society of Dublin. 



ON PYROGLYCERIN. BY M. SOBRERO. 



M. Sobrero has given the above name to a compound which he 

 obtained by treating glycerin with a mixture of nitric and sulphuric 

 acids, in the same proportions as for preparing gun-cotton. This 

 product is liquid, and explodes very violently ; its taste is very di- 

 stinctly bitter, and is a very active poison ; two or three centi- 

 grammes immediately kill a dog. It is a powerful oxidizer ; mixed 

 with nitric acid, it forms a kind of aqua regia. It has not been 

 analysed, but is suspected to contain nitric acid. — Journ. de Pharm., 

 Avril 1850. 



PREPARATION OF SULPHUROUS ACID. BY M. BOUTIGNY. 



The author having occasion to prepare a large quantity of sulphu- 

 rous acid, advantageously employed a cast-iron apparatus for this 

 purpose in decomposing sulphuric acid by charcoal. In this opera- 

 tion the iron was not at all acted upon. Although many manufac- 



