58; 



iCtENTlFIC NEWS. 



Its diaineter could not be meafured, but it appeared like a 

 flar of the eighth magnitude. It leems nearly equal to that of 

 Certs, or the planet difcovered by Piazzi. 



Difcovery of Fluoric Add in the Topaz* 



IN the year 1797, M. Vauquelin analyfed the Saxon topaz, 

 and tmind its conftituent parts to be, iifex 3 J, alumine 6S. 

 Mr. Dercolils foon afler ejiafnined the Brafiliari topaz; biit as 

 there wais a lofs of 18 per cent, in his firft analyfis, and 12 in 

 his fecorhd, he did not think fit to publifli the refalts of his la- 

 bours at that time; and other circuinftances prevented him 

 from purfuing the inquiry, as he had inte-nded. 



Not long ago Mr. Klaproth wrote to Mr. Hauy, that he had 

 covered fluoric found fluoric acid in the Saxon topaz. Mr. Laugier made fe- 

 Sxon topaz. veral experiments to verify this difcovery, but without fuccefs. 

 It is true in the analyfis with potaHi he found a deficiency of 

 Sulphuric acirl 16 per ce»t. but though he reduced the topaz to an impalpa- 

 *'*Ii'!f;'r °^ ^^ ^^^ powder, and did all he could to expel the fluoric acid from 

 it by means of the fulphuric, he was unfuccel'sful. Mr.Vau- 

 cfiuelin on his rielurn applied himfelf to the fame rcfearch, and 

 we here prefent the refutt-ofhrs labours. Not knowing what 

 procefs Mr. Klaproth had employed, he tried that which' 

 feeraed to him moil likely to fucceed. He firft heated the to- 

 paz with caullic potafli in a filver crucible in the ufual way. 



Ssxon topar 

 anftlyfcd by 

 Vautjuelin. 

 ^r'afiliah by 

 Pefcotils, 



Klaproth d'lf- 



pcUing it. 



Vau quell n 

 treating the 



afli"nd fulpbu- AfttT he bad diluted the mafs with water, he introduced it into 



ricacid expelled ^ retort, and poured on it fulphuric acid. White fumes foon 



arofe, and thefc, being colleded, exhibited all the chara6ler-. 



iftics,of fluoric acid combiiied with filex. The latter came 



alinoft wholly from the ftone/ as the retort was not perceptibly 



attacked by the acid. 



The Brafilian, The fame experiment with the Brafilian topaz gave the fame 



H" ^fuir^* refult; and there is every reafon to believe, that the Siberian, 



vvhich Mr. Vauquelin is now analyfing, will afford the lame 



produ6ts. Thus vve may now confider this gem as a filiceous 



compound, confif^ing of fluoric acid, alumine, and filex, or a 



Tm>axatrue true alumino-filiceons fluate; and the difcovery mufl be confi- 



alumino fiiiccous Jered as of the higheft importance io mineralogy. 



i^uate. 



* Bulletin dcs Sciences, No, XC. p. 28:^, Sept. 1804. 



Mr. 



