MAGNESIAN £A-ftTH. 323 



After being left three hours to coo!, it was moiftened with Leaving to digeft 

 water and put away till next day, a part of it was then lixivi- ^ftenedwith 

 aled ; the folution being made clear and treated with ammo- cold water, 

 nia, gave an abundant and very white precipitate. This cir- Lixmatin £ > 

 cumftance indicating that much of the magnefia was combined 

 with fufphuric acid in the operation, all the remainder was 

 lixiviated. The very clear lixivium, evaporated properly, 

 produced at the firft cryftalization a pound of fulphate of mag- a nd cryfhruings 

 nefia in beautiful cryftals. The remaining liquor gave on foe- 

 ceffive evaporations a pound and half more of the fame fait 

 in fine cryftals, very dry and very white. The liquor pro- fine cry (his in 

 duced cryftals to the Iaft drop, and the mother-water never j^j" datfce are 

 became foul. The mother- 



The mixture which remained after lixiviation was roafted wat f ; f V3 &" , 



rated lucce ffi veJy 



a fecond time, and again produced fulphate ot. magneua : It g j ves cryftals to 



was then thrown away, although apparently it would have ths laft dro P- 

 • u j r i L < i re «i . c r The refiduurn 



yielded more fulphate of magnelia after another torrmcation. roa ft ec j again and 



In another experiment, pure fulphur was ufed inftead of the re-lixiviaud 

 pyrites ; it was eafy to forefee that the refult would be the f™ more cry " 

 fame; it was however defirable to prove it; and the refult Pure fulphur 

 wa.perfeaiyfctUfeaory. > 'ttm^ 



The ufe then which may be made of this earth, confifts in iron anfwers 

 forming with it fulphate of magnefia. The means by which J?"* 11 ? ™ dI * , 

 this may be done are perhaps the moft fimple poflible. It is phate of mag- 

 fuflicient to reduce to powder the earth and the fulphur, or nefi a in the ,ar e e 

 the fulphuret of iron, where it can be eafily procured, as may ne fi a n earthed 

 be done at EaudiiTero. Thefe fubfiances mould be mixed in pyrites, fimiJar 

 almoft equal parts; for it is ufeful to proceed with an excefs t0 e oies ° !I,s * 

 of the earth, and the more fo, as its coft is almoft nothing : 

 The mixture mould be terrified in an oven or kiln, heated to 

 the degree at which fulphur inflames, and when there appear no 

 more jets of fiilphurous flames, the kiln is to be left to coot. 

 The matter being then drawn out (hould be moiftened with 

 water in citterns, and left for fome days, only taking care to 

 ftir it in that time. 



The part of the fulphur which in burning had only paiTed to 

 the ftateof fulphurousacid, oxigenates gradually, or the fait, 

 which at firft was but a fulphite changes to a fulphate. The 

 matter is then to be lixiviated, in the fame manner that is iifed j 



for nitrous earths, the liquor fufllciently evaporated, and left 

 to cry ft ali ze by cooling. 



Y 2 Asoihsr 



