Mineralogy — Geology. 375 



plants from which they are extracted in the state of pure starch. Their 

 conversion into amidine is explained by the fact that heat is employed in 

 preparing them. Agreeably to this idea, M. Caventou has met with some 

 specimens of sago, which are very sparingly soluble in cold water, and 

 others which do not dissolve in it at all. In these cases it is supposed 

 that so a low temperature was employed in the preparation, that the conver- 

 sion of starch into amidine is only partially effected. 



Arrow-root is exactly similar in its chemical properties to the starch 

 prepared from the potato, and may be regarded as unchanged starch. 



It follow 1 ! from these researches that the amylaceous principle of the po- 

 tato may be substituted for arrow-root, and that a substitute for sago and 

 tapioka may be made from the same material, by converting it into ami- 

 dine by means of heat. — (Extracted from the Ann. de Chim. et de Phys. vol. 

 xxxi.) 



26. Muride, a New Substance, intermediate between. Chlorine and la- 

 dine. — At the Academy of Sciences there was read on the 3d July a me- 

 moir by M. Ballart, on a particular substance contained in sea water, and 

 which he proposes to call muride. It is of a blackish red colour, exhibits 

 a disagreeable odour, similar to that of the oxides of chlorine ; its taste is 

 equally disagreeable, and it exerts on the animal economy a deleterious ac- 

 tion highly energetic. It boils at 37° Cent., and consequently volatilises 

 with a facility which forms a remarkable contrast with its density, which 

 is considerable. It congeals at 18° below zero, and it does not conduct 

 electricity. Relatively to its action on different simple bodies, muride is in- 

 termediate between chlorine and iodine. — Le Globe, No. 85. 



III. NATURAL HISTORY. 

 MINERALOGY. 



27. Crystals of Sulphur in Galcena. — The crystals of sulphur I found 

 accompanying sulphuret of lead, in a vein of the latter, in sandstone, at 

 Redpath, about five miles north of "Wallington. Sometimes it occurs in ca- 

 vities which appear from their shape to have once contained crystals of 

 galaena, but which has been decomposed ; indeed, where the sulphur oc- 

 curs with the galaena, it appears to be a result of the decomposition of the 

 latter. — Note from W. C. Trevelyan, Es(/. 



23. Native Alum found at Calingasto, in South America. — A formation 

 of native alum occurs at the place which is situated among the mountains, 

 and on the banks of the Rio di San Pian, about 40 leagues north of the 

 commencement of the valley of Uspallota. Many specimens of the alum 

 exhibit a fibrous texture and a silky bark. It is excellent, and is used in 

 these provinces for all domestic purposes. The other day on my way to 

 the Portillo, on the banks of a small rivulet, I saw there a formation of 

 alum earth, where the alum is imbedded in earth in small round masses. 

 — Extract of a letter from Dr Gillies to W. ('■ Treieh/an, l'sq. 



GEOLOGY. 



29. Notice of the Explosion of. a Volcano in the Andet.—\ have just n 

 turned from an extremely interesting journey across the Cordilleras as fin 

 as the Pacific, by a piss rail ed the Portillo, to the south of Mendoza, mucli 



