No. III. 



Analyses of the Chrysoberyls fro?7i Haddam and Brazil. By 

 Heni'y Seybert. — Read, 5th March, 1824. 



In the summer of 1833, I visited Haddam, in the State 

 of Connecticut. Among; the various substances there col- 

 lected, was the Chrysoberyl, a mineral much esteemed on 

 account of its rarity. It occurs disseminated in a coarse 

 grained granite, in which the predominant ingredient is 

 a white feldspar, which Professor Berzelius regards as AU 

 bite, perfectly resembling that of Finbo. In the same gra- 

 nite this celebrated chemist observed the Cobmibite* It 

 is also associated with greyish quartz, manganesian garnet 

 of a fine blood red colour, and a yellow granular substance, 

 which some mineralogists supposed to be a variety of the 

 cymophane ; but from its inferior hardness and general clie- 

 mical composition, I recognised it to be common beryl. 



For the earliest chemical information concerning the 

 Chrysoberyl, we are indebted to Professor Klaproth. He 

 published his analysis of it in 1795,t and gave the following 

 constituents of it, viz. alumina, 71.50 ; hme, 6.; oxide of 

 iron, 1.50 ; silica, 18. ; loss, 3. Berzelius presented us with 

 a formula founded on this composition ;t but from his expe- 

 riments with the blowpipe he was led to conclude that it 

 contained no lime, and that it was a subsilicate of alumina. § 

 In this he was apparently confirmed by Professor Tiiom- 



* Essai de' 1' Emploi du Chalumeau, p. 243. 

 t Beitrage, vol. i. p. 97. 



X Systeme de Mineralogie, p. 219,— C*S+18A*S. 

 (> Essai de' 1' Emploi du Chalumeau, p. 325. 



