Red coloured JVater of a Lake in South Prussia. 243 



li oxide of iron 

 ^ oxide of manganese. 



Analysis of the Pearl-sfone of Hungary. 



The mountains of Tekelbart in Hungary, from which so 

 many rare fossils are extracted, among which are the beau- 

 tiful changing opals, furnish that also which Werner has 

 classed in the system next to Pitch-stone, under the name 

 of Pearl-stone. 



Tiiat which M. Klaproth subjected to analysis is of an 

 ash gray colour, traversed by yellow bands. It is found 

 between Kerestur and Tokai, in alternate strata separated 

 by others of argillaceous porphyry. 



The specific gravity of this fossil is 2340. It swells up 

 by the blowpipe like zeolite; but it does not fuse into a 

 globule. 



A piece calcined for two hours in a moderate fire lost 

 nothing of its form. Its colour had become reddish brown. 

 It had experienced 4i per cent. loss. 



Pearl-stone was completely vitrified in a porcelain fur- 

 nace in a clay crucible, as well as in a crucible lined with 

 charcoal. 



A hundred parts of the pearl-stone of Hungary, treated 

 successively by soda and by acids, gave in their analysis: 

 Silex - - - 75-25 



Alumine - - - 12 

 Oxide of iron - - 1*60 



Lime ... 0*50 



Potash - - - 4-50 



Water - - - 4-50 



98-35 



[To be continued.] 



XLI. Examination of the Red coloured Water of a Lake near 

 Lubotin, in South Prussia. By Professor Klapkoth*. 



J. iiF South Prussian gazette of tlic 8th of February 1800, 

 and the Berlin gazette of the 1 3th, gave an account of a 



phiEuomenon 



• From Schcrer's Ail^^rmcines Journal dtf Chemie, No- 33. — About 

 Iwcnry years ago Mr. Achard examined water tinged in a siinilar m-inncr, 

 wliich hi. obtained from a l,.kc near Srrautzherg. In the month of Decem- 

 ber, 17 J7, the ice of liiu Like was coloured red, and coatiuwed sc .11 tho 

 n 1 i.aonth 



