3G6 Condrodite. 



of well prepared and pointed cliarcoal was truly interesting, 

 while iho troughs are raised and lowered by levers which 

 are easily moved by placing the foot on a treadle. 



Art. XXIII. — '^Additional facts respecting the Condrodite 

 and its identity with the Sparta mineraL [Maclureite of 

 Seyherf, Brucite of ClenveLindy) in a letter addresstd to 



the Editor^ dated Philadelphia, August 26, 1822. 



Sir, 



Since my communication concerning the JMacJu^eite was 

 transmitted to you, I observed, in the Annales des Min^ s,t 

 a memoir by the late Professor Haiiy on the Condrodite. 

 By crystallographical investigation he identified that sub- j 



stance with the mineral found ne«ir Sparta, N. Jersey ; he 

 states, tliat Berzelius arrived at the same determination by 

 Analysis, and that he considered it a Silicate of Magnesia. 

 From the above statement, it was evident to me, that some 

 error existed with regard to the composition of the^^e sub- 

 stances, because the experiments, related in my paper con- 

 cerning the Maclureite, unequivocally prove the presence of 

 fluoric acid in the mineral found in New-Jersey. As the 

 celebrated Sw^edish Professor announced the chemical inde- 

 tity of these substance?, without his having detected Fluoric 

 AcidjJ 1 was induced to procure some of the mineral from 

 Finland, and obtained a small quantity of it. The speci- 

 men was brought from Sweden by Mr. WilHam Maclure; 

 it was imbeded in a gangue of Carbonate of Lime, associa- 

 ted w^ith bUie Spindle^ and a greenish mineral resembling 

 Pargasite; from these substances it w^as, as much as possi- 

 ble, separated by mechanical means. To free it entirely 

 from the Carbonate of Lime it was boiled with Acetic Acid, 

 the resdue, after this treatment, weighed 1.20 grammes, it 

 was calcined at a red heat, during one hour, 'in a platina 

 crucible, with six times its weight of crystallized sub-carbo- 

 nate of Soda, the matter after calcination was treated with 



* Received too late for liisertioo with Mr. Seybert's Aualoj 

 t Aurmles des Mines, Tome, C. p. 527. et sequcn. 



+ See Journal of Royal lastitutioo i;f G. B. for 1822. No. 24 



Ed. 



