473 



Zinkenite. S, Pb + Sg, Sb. 



Plagionite . . . 4 (S, Pb) -f 3 (S3, Sb). 



Jamesonite . . . [5 (S, Pb) + S3, Pba] + 4 (S3, Sb) ? 



Feather ore oflead 2 (S, Pb) + S3, Sb. 



Boulangerite . . 3 (S, Pb) + S3, Sb. 

 A mere inspection of the formulae is sufficient to show 

 that each mineral in this list is distinct in composition from 

 that whose analysis has been given above. There is, however, 

 an ore possessing a constitution perfectly analogous to the Irish 

 mineral — namely, the sprodglaserz of Mohs and Werner, 

 or what Dr. Thomson calls brittle silver glmice. The formula 

 of this mineral Rose has shown to be 6 (S, Ag) + S3, Sb ; 

 so that it differs from Kilbrickenite merely in containing 

 silver instead of lead. 



The following note — " On a principle for producing an 

 everburning Flame," by George J. Knox, Esq., was read by 

 the Secretary : 



** A belief in the discovery of an everburning lamp appears 

 to have been prevalent in all ages ; and tradition informs us 

 that lamps have been found in tombs, where they have con- 

 tinued burning for upwards of lOOO years, of which mention 

 has been made in the works of St. Austin, Plutarch, Pliny, 

 Ludovicus Vives, Baptista Porta, and Licetus. The 

 Rosecrucians,* who laid claim to the knowledge of every- 

 thing mysterious, pretended to have rediscovered the secret 

 of their construction, which was supposed to have been 

 buried in the tomb of their founder. Dr. PIott,t in a 

 treatise which he has written upon this subject, alludes to a 

 lamp mentioned by St. Austin in his book de Civitate Dei, 

 which was hung up in the temple of Venus ; and to another 

 found in the tomb of Pallas the Arcadian, who was slain by 

 Turnus in the Trojan war, which continued to burn after 



♦ Spectator, vol. v. No. 379. 



f Lowthorp's Abridgment of Phil. Trans, vol. iii. (636). 



