On the Compdratlve Height of the Mountains, Sec. 39J 



This limple table will fhew plainly how neceflary it is to 

 accommodate the flux to the variety of the ore. If from 

 this colleftion you wifh to obtain carbonated regulus, it is 

 obvious that, in order to faturate them equally, the iron 

 contained in No, 3 ought to be prcfented with double the 

 quantity of c3,rbon neceflary to carbonate No. i ; No. 5. 

 with a trip!e quantity j that of No. 6 with more than 3 v : 

 and as I have proved that this effe6l will be chiefly produced 

 with the ufe of a calcareous earth, it will at once be con- 

 ceived how far this fubftance is to be ufed as the inftrumeiU: 

 of alteration. 



In the recipes adduced in this and the preceding paper, I 

 have always noted charcoal as a conftituent of each mixture. 

 Since I difcovered that the contact of calcareous earths -con- 

 veyed carbonation to the metal, by the decompofition of the 

 carbonic acid, I havl* reduced the proportion of charcoal 

 commonly ufed in tlie flux, and have, in the treatment of 

 nioft iron-ftones, even abandoned it altogether: however, as 

 my experiments have not yet extended univerfally to primary 

 ores, I have, in the mea^i time, retained it as a confl:ituent 

 part of the folvent. 



XII. On the Comparative Height of the Mountains of the 

 Earth, the Moon, and Fenus *, 



OCHROETER, the learned aflronomer of Lilienthal, wh» 

 {las fcveral excellent tclefcopes by Heffchel, publifhed feme 

 time ago a work on the height of the lunar mountains, ax 

 compared with thofe of the earth ; and lately he has pub- 

 liflied a new work on the height of the mountains of Venus. 

 Faujas, who not long ago imdcrtook a journey into Cer- 

 piany, of the utmoft importance to the fciences, brought 

 back with liim thefe two works of Schroeter, We there fee 

 |he manner ir^ which that indefatigable aflronomer makes 



♦ Fiom tlic Journal de Phyf(iue, Prairiat, An. 7, 



his; 



