296 Scientific Intelligence. — Geology. 



passing into greenstone. Its igneous origin is beautifully seen 

 in one part, where it has torn off a part of the slate-clay (now 

 imbedded in it), and which has evidently undergone a sort of 

 semifusion. From the following analysis it will easily be seen 

 that it has a very different constitution from any felspar. It 

 effervesces violently with acids, and does not gelatinize : its con- 

 stituents are, silica, 37.20 ; alumina, 9.75 ; iron, 20.00 ; lime, 

 8.57; magnesia, 3.78; carbonic acid and water; 20.80, = 

 100.10. 



10. Inflammahle Matter in Carnelian. — In consequence of 

 some remarks contained in a memoir of Dufay, published in 1732, 

 relative to the decoloration of carnelian, Gaultier de Claubry 

 heated, in a porcelain retort, some fragments of carnelian with 

 deutoxide of copper. There was a sensible emission of gas, 

 which appeared to be carbonic acid, and the fragments were de- 

 prived of their colour at the surface. In another experiment 

 with pulverized carnelian, the development of gas was much 

 greater, viz. 29 cubic centimetres from 100 grammes of carne- 

 lian. This appears to leave no doubt of the existence of organic 

 matter in carnelian quartz, and to the presence of which it owes 

 its colour. At the recommendation of Thenard, the experimen- 

 ter calcined alone 100 grammes of carnelian, which lost in the 

 operation 1.169 grammes, and furnished carbonic acid and some 

 inflammable gas, besides an acrid liquor, which strongly red* 

 dened turnsol ; no ammonia was disengaged from the liquid 

 when treated with lime ; the residue was of a greyish-white. It 

 follows, that the colour of carnelian is owing to inflammable 

 matter. A portion of the loss may be occasioned by the escape 

 of water contained in the stone. 



11. Fossils in Granite. — M. de Seckendorf has found in the 

 Hartz, in the midst of a quarry situated near the causeway 

 which leads to Ilartzberg, fragments of greywacke, containing 

 petrifactions imbedded (empates) in granite. M. Hartmann, 

 author of the Mineralogical Dictionary, confirms this statement. 



12. Geological Maps. — In the year 1826 aGeognostical Map 

 of Germany, in forty -two sheets, was published in Berlin by 

 Simon Schropp & Co., which has become well known to the 

 geologists of this country and the continent. Since that time a 

 corrected edition has appeared, and it is with much pleasure we 

 learn that a third, and very much improved, edition is nearly 



