1815.] Royal Institute. 463 



Turkey, and, it is pretended, by a single workman in Constantinople, 

 who possesses the secret. 



The falls of stones from the atmospliere, since the reality of the 

 phenomenon has been constated, are observed so often, that by and 

 by the most astonishing thing will be the long incredulity enter- 

 tained respecting them. A remarkable fall took place this year in 

 the department of the Lot-et-Garonne. It happened on the'fjth of 

 September, and, as usual, in fine weather, with a strong explosioa 

 and a wlutish cloud. Tlie number of stones was considerable ; one 

 of them was said to weigh 18 pounds. Tiiey were scattered over a 

 surface of about a league radius. Their external characters and 

 composition are absolutely the same as in other stones of the same 

 origin, only their fracture has tints a little more marbled than 

 common. Excellent reports by two good observers at Agen, MM. 

 de Saint-Amans and Lamouroux, have made us fully acquainted 

 with the details of the phenomenon. 



M. le Comte Berthollet has presented to the Class, on the part of 

 Mr. Tennant, one of the stones that fell last year in Ireland, and 

 which resemble all the others, excepting that they contain a little 

 more iron. 



It is known, and we have had repeated occasions to mention it, 

 that the stone called arragonite furnished the strongest objection 

 that could be produced against the employment of crystallization in 

 the classification of minerals ; because chemists had found no ditfi^r- 

 «nce between its composition and that of calcareous spar, though 

 the crystalline forms be essentially distinct. This objection is now 

 removed. IM. Stromeyer, Professor of Chemistry at Gottingen, 

 has discovered the constant presence of three per cent, of strontian 

 in arragonite, while none exists in calcareous spar. M. Laugier, 

 Professor in the Museum of Natural History, has repeated this 

 analysis, and obtained the same result. It remains to be explained 

 how the addition of so small a quantity of a constituent can change 

 so completely the form of the primitive molecule of a mineral. 



CTo be continued.) 



Article XII. 



SCIKNTIFIC INTELMnJiXCE; AND NOTICKS OF SUn.fKCT5 

 COxNNKCTED WITH SCIENCE. 



I. River Missouri. 



The river Missouri, which was navigated in ISOS and 1806 by 

 Captains Louis and Clarke from its jtmctioii witli the Mississippi to 

 itii s(jurce, runs a couisc east and south of above ;i()00 miles. It 

 rises in a very elevated group of mountains situated between north 

 latitude 41° and 45', and about west longitude 112". TJic height 



