df Copffr and of Iron. 227 



Was of a grecnidi white, and foluble in a great quantity of 

 water; but, paffing to a much det-pcr green, quickly lell to 

 the bottom. A j^ruflfiate or a gyllate poured into the fa'id 

 fob.ilion, occalioned no change till it had ilood a confiderable' 

 time cxpofed to the contact of the air. By potalh, and by 

 foda, a white precipitate was thrown down, which cpiickly 

 aOumed a grce'n tinge ; and that tinge increafed fo much as 

 to become a vcrv deep crafs green in a few minutes. Am- 

 monia occafioned a wliitc precipitate, which was redillolved 

 bv an cxccfs of the ])recipitant. 'fhe aifimoniacal fokilion 

 affiuncd the lame grecnifTi tinge, and (peedily depofited an.' 

 oxide of iron, which was tirll: of a deep green, but inftan- 

 tancouOv became black, with fonie yellowifh ochrey parti- 

 cles on the furface. ff, however, thefe precipitations were 

 cffecled in a bottle well flopped, and defended from the con- 

 taof of the atmofjihere, no change of colour took place ; aha 

 that portion which was diliblved by ah excels of amnionia 

 remained in the I'olution. In endeavouring to diltil, or to 

 f;vaporate, the water of this colourlcfs folution, in order to 

 obtain cryftals, it became of a light green, the intenfity of 

 which augmented, as the dillillation W'as continued. I could 

 not, (Iiereforc, hope to procure this fiilt in a cryflalline form. 

 Hence, it is evident that wc have a vvhilC muriate of iron, 

 which, as well as the oxide it contains, is very fnfceptible 

 of alluming an addition of oxvgen; for to i\\?.i alone I attri- 

 bute the precipitation caufed in a folution of that fait, into 

 whith the different reagents above menlioned had been 

 poured ; a precipitation which did not take place till after 

 it had been ex'pofed in a fituat'ion where il could abforb the 

 ijuamity of oxygen' ne'eCirary to produce a change in its prin- 

 ciples. 



This folution of white nun'iatc of iron, when expofed to 

 the air, becomes green, and is theVi in the (late of green 

 mufiat'c, well known. At a certain degree of oxidalion, I 

 have obferved the precipitate formed, to be foluble in the car- 

 bonates of potj'fh and of foda, and ftill more fo in that of 

 ammonia; but, upon abforption of f),\ygen, to be quickly 

 abandoned bv ihcm, and then to tal.l to. the bottom, in a 

 blackifti powder mixed wiih yellow. If into a folution of 

 preen nmriate of iron niiric acid is poured", both ru]uors 

 Dein!:^ cool, and not too concentrate, the miuialO w ill become 

 ftf a Ijlackifli brown, not unlike malaic of iron. Precipitated 

 by the alkalis, it vields a black powder, no longer foluble in 

 (hem, btit which rcfernblej, in every refpeiil, common black 

 oxide of iron. 



If lhi« green muriate of iron is further expofed to the air, 

 i' 'J, the 



