366 Condrodite. 



of well prepared and pointed charcoal was truly interesting, 

 while the 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 rvith the Sparta mineral. [Maclureite of 

 Seyhert, Brucite of Cleavel and,) in a letter addressed t» 

 the Editor, dated Philadelphia, August 26, 1822. 



Sib, 



Since my communication concerning the J[Iaclureite wa^ 

 transniitted to you, I observed, in the Annales des iMia( s,t 

 a memoir by the late Professor Haiiy on the- Condrodite, 

 By crystallographical investigation he identified that sub- 

 stance with the mineral fouml near Sparta, N. Jersey; he 

 stales, that 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 these sub- 

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

 cerning the Machireite, unequivocally prove the presence of 

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

 celebrated Swedish Professor announced the chemical inde- 

 tity of these substances, without his having detected Fluoric 

 Acid,J 1 was induced to procure some of the mineral from 

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

 men was brought from Swedm by Mr. William Maclurej 

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

 ted with biue Spinelle. and a greenish mineral resembling 

 Pargasite; from these substance? it was, as mucli as possi- 

 ble, separated by mechanical means. To free it entirely 

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

 the res'due, 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 weii.ht of crystallized sub-carbo- 

 nate of Soda, the matter after calcination was treated with 



* Received too late for insertion with Mr. Seybert's Analogies. — Ed. 



t Annales Jes Mines, Tonif , C. p. 5"27. et sequen. 



t See Journal of Royal Institution of G. B. for 1822. No. 24, 



