1819.] Dr. Vest on Vestium. 347 
fully, but without renewing the water. I then lay down the 
crystals to allow them to dry from a small residue of the solu- 
tion before dissolving them again. 
The ley in which the white flocks swim, and which is often 
rendered impure by oxide of iron, I collect in a glass, and after 
some little agitation decant it off from the oxide of iron at the 
bottom of the vessel ; then mixing it with more sulphate of pot- 
ash, I evaporate it again, to free it still more completely from all 
the nickel which it may contain. The crust of salt obtained is 
washed, as before described, with the requisite quantity of cold 
water. The cold ley contains sulphate of vestium, partly in solu- 
tion and partly swimming in it in light flocks, often contaminated 
with iron, and very frequently with cobalt. When no more 
nickel crystals will separate, though the liquid has a green 
colour, it is a proof that too little sulphate of potash has been 
dissolved in it. 
The green nickel crystals and the salt crusts obtained by the 
above described processes I mix with an additional quantity of 
sulphate of potash, pour water over the mixture, and set it na 
warm place so that the salt may dissolve. I then allow the 
liquid to evaporate to dryness. The crystals of vestium which 
existed in the crusts, and which are thus separated, I remove 
from the nickel crystals by decantation. I treat the crystals and 
the liquid again and again in the same way till the nickel erys- 
tals assume a fine green colour. If it be our object to obtain 
pure nickel from them, it will be necessary to subject them to 
several additional crystallizations. 
This is the way by which I separate all the nickel and all the 
uncombined oxide of iron. When the separation is completed, 
the solution is colourless, or nearly so. The vestium is now 
separated from it in the followimg manner : 
{ precipitate the liquid with carbonate of potash, which | 
boil with it, and then filter. The solution may be likewise eva- 
porated to dryness, and heated to redness with carbonate of 
poet in a silver crucible. It may be then boiled and filtered. 
at remains on the filter, being sufficiently edulcorated, may 
be dissolved in nitric or muriatic acid. It is necessary to boil 
the vestium with the ley of carbonate of potash. This occasions 
no sensible loss of the vestium, though it be slightly soluble in 
cold potash. When the sulphate of vestium is fused with the 
eet a sulphuret of vestium is often produced, when the ley 
appens to be polluted with charcoal. On that account, the 
boiling with the potash is preferable. \ 
The vestium, after being heated to redness and well edulco- 
rated, is digested cold in diluted muriatic acid, which scarcely 
acts upon it. The liquid is then poured off, and it is boiled in 
muriatic acid, which dissolves it readily. The vestium which 
has been boiled with the alkaline ley dissolves easily in cold 
muriatic acid, We may likewise filter the muddy ley containing 
D) 
we 
