354 Artahjis and Synthejis of Alkalies and Earths. 



tion was finifhed there was not a fingle atom of precipitate 

 produced in the liquor. This experinx'iit, which I think 

 one of the mod exaft for afcertaining the ammonia that 

 Inight have exifted or been produced in this operation, evi- 

 dently proves, that if the above authors obtained anv, this 

 alkali nmft have arifen from fonie other caufe than that of a 

 decompofition of the fubllances emploved, if thev were pure. 

 The refiduum examined in three operations gave no inag- 

 nefia. I muft here obferve that I employed fulphur, which 

 I fublimated iiiyfelf. 



To remove all doubt refpe'5lini]f this experiment, and to he 

 more certain of my refults, 1 made a fecond, but (lill without 

 fuccefs. ' 



The apparatus being arranged as in the preceding experi- 

 ment, I put in the place of the fulphate of iron muriatic 

 acid, and began my operation. After all difengagemcnt had 

 ceafed, I took the muriatic acid, which I evaporated at a 

 gentle heat; but, not being able to obtain an atom of faline 

 refiduum, I poured lime into the fmall quantity of litjuor 

 which remained. I added more than was necefTarv, but 

 tiotwithftanding all mv precautions I had no difengagemcnt 

 of ammonia. It is now f;^en, by thefe tv.'o experiments, that 

 no difengagemcnt of ammonia is produced ; for, I mu(l re- 

 peat it, muriate of ammonia would have been formed in the 

 laft, and in the firft Iron would have been precipitated : no- 

 thing is difengaged but fulphurated hydrogen gas in very large 

 quantity, and the refiduum contains no magnefia. 



Exp. XIX, This laft experiment the above authors made 

 by taking the charcoal of fugar, which they mixed with lime 

 extrafted from marble: this mixture being expofed to a 

 llrong heat in a platiua crucible well flopped, they obtained 

 alumme and magnefia. 



As they do not give the proportions of the matters em- 

 ployed in this experiment, nor the quantities of the products 

 obtained, I prefume that they confidered it only as a new 

 proof in favour of the theory they have eftablifhed. 



I repeated this experiment, and employed charcoal of 

 fugar and pure charcoal. With the charcoal produced from 

 40 grammes of cryftallized fugar, T obtained a little alumine: 

 the produ6l collefted weighed only fix centigrammes; per- 

 haps it contained magnefia. In my fecond operation, when 

 I employed pure charcoal, I had not a fingle atom of the 

 above-mentioned earths : it is therefore feen that the pro- 

 du6ks obtained in this experiment arofe from the impurity of 

 the matters tmployed. 



• Conclujtoji . 



