O.'jG French National Injl'ittitc ; 



produces this triple fait in its full purity. In the lirft of 

 thcie two cafes, the atlinitv of the fulphate of ammonia for 

 the ful|iliale of fotla oppofes the total and generally admit- 

 ted decon)i)ofition of the fulphate of ammonia by the muriate 

 of foda. 'I his triple fait ads a dillinguiihed part in the fa- 

 brication of fal ammoniac : it cryflallizes regularly ; does not 

 efllorefee in the air; has a favour, at firlt pungent, then 

 flightly bitter ; is decompofed by foda, which transforms ic 

 wholly into fulphate of foda; decrepitates in the fire, fwells 

 np in it, and futfers to be difengaged, firft annnonia, and 

 then acid fulphate of ammonia, "while pure fulphate of foda 

 remains at the bottom of the veiTel. 



A New Poiijhing Rouge. 



Chcmiftry, which can contribute in fo etTeflual a manner 

 to the ia^provemcnt of the arts, docs not loie this important 

 dire(Slioi>, and, in this refpecSt, defcends to the minuteft de- 

 tails. ]n coniequence of a report prefented to the Clafs, on 

 a rouge for polifliing, C. Guyton communicated fome ob- 

 fcrvalions on ochry reds fimilar to thofe of Almagra in Spain, 

 and which, in many cafes, might be fubilitiUed for red 

 oxide of iron or colcothar. He mentioned as a very oeco- 

 iiomical proccfs, and proper for giving the lart polKh to the 

 hardeil matters, the ufe of bits of old hat, which, as is well 

 known, are dyed with iron. Ey immerfing thtfc pieces of 

 hat for fome minutes in fulphuric acid, the iron which they 

 contain pafli^s to the ttate of red oxide, and they then be- 

 come excellent pieces for pollfhing, and may be ufed in the 

 Head of the finelt rouge. 



Anahjis of an Ore of Uraiuum. 



C. Sage communicated to the Clafs the analyfis he made 

 of a fulphurous ore of uranium, of a blackilh brown colour, 

 without a regular form, and brought from Erbenfloch in 

 Jbaxony. 



This ore, which has fome external relation to that gene- 

 rally known under the naine of fechhlende, is however 

 dificrent in iti colour, which is brownilh and dull, and in 

 exhibiting fome p\ ritous points. It contains iron, the pre- 

 fcnce of which was manifcltcd by the magnet^ after the tor- 

 rification nccciTary to difengage the fulphur. 



It re fu Its from the diiTerent" trials to which this fubftance 

 was fubjccfed by C. Sage, that loo parts of it contain 78 of 

 uranium, 20 of iron, a'nd 2 of fulphur. 



Thinking, like all thofe who poflefs any elevation of 

 wind, and a philofophical fpirit in cultivating- the fciences, 



that 



