On a m:!icral Prodacilon from Devo7i shire. ?5 



thtir diflcrbiU properties as to make them apparently one, 

 has taken it.s full effect, it will not be easy to separate iheni ; 

 and this will be more particularly the case when neither of 

 those substances is remarkable for exercising a powerful 

 action upon others. 1lic method of analysis, therefore, 

 does not promise much success ; and the labour of syn- 

 tiiesis is sulTicient to deter any individual from the under- 

 taking* 



[To be Continued.] 



V. An Account of some analij Ileal Expcrhnents on n ml/ieral 

 Prodiic/lon fom Dcuonskirc, consisting princl[jullij of 

 ylliimlne and IJ'atcr, By IIumimhiy Daw, Escj. FJt.S. 

 Pr(fessor of Cheynlslnj In the lloijul Institution'^'. 



I. Prdlmlnary Ohscrvcdlons. 



JL his fossil was found many years ago by Dr. Wavcl, in 

 a quarry near Barnstaple: Mr. Hatchett, who visited the 

 place in 1796, described it as lllling some of the cavitits 

 and veins in a rock of soft argillaceous schists When first 

 made known, it was considered as a zeolite; Mr. Hatchett, 

 however, concluded, from its geological position, that it 

 inost probably did not belong to that class of stones ; and 

 Dr. Babineton, from it? phvsical characters, and from some 

 cxpcrimenTs on its solution in acids, made at his request bv 

 Mr. Stockier, ascertained that it was a mineral body as yet 

 not described, and that it contained a considerable propor- 

 tion of aluminous earth. 



It is to Dr. Babington tliat 1 am obliged for the oppor- 

 tunity of making a aencral investigation of its chemical 

 nature ; and that gentleman liberally supplied mc with spe- 

 (. imcns for analysis. 



II. Sensible Characters of the FossU, 



The most eonmion' appearance of the Jbssil is in small 

 hemispherical groiq)S of crystals, composed of a number of 

 filaments radiating froiii a conniion centre, and inserted on 

 the surface of the schist ; but in some instances it cKists a:-; 

 a collection of irregularly disposed prisms forming small 

 veins in the stone : as jet, 1 believe, no insulated or distinct 

 crystal has been found. Its colour is white, in a few cases 

 with a tinge of gray or of green, and m some pieces (appa- 



• From the Tia-t'nrlionf '>/"/'if Fii>itr.l ^vciuly for ISC'* 



C 2 rontly 



