1819.] Dr. Vest on Vestium. 349 
Some of the Properties of Vestium. 
When vestium has been purified, it exhibits the following 
properties : 
A.—Inits Salts. 
1. Oxide of vestium is soluble in sulphuric, muriatic, nitric, 
and acetic acids, and forms with them colourless solutions, hav- 
ing a metallic taste, and yielding by evaporation white crusts, 
or small needles like sulphate of lime. It separates from all the 
acids in white light flocks, when these crusts or needles are 
again dissolved in water, and allowed to remain at rest. These 
flocks are soluble in an additional quantity of acid, and when the 
liquid is heated. 
In these properties, vestium agrees in part with some of the 
easily soluble metals; but the salts have the greatest resem- 
blance, at least in the action of several reagents on them, with 
the salts of lime. 
2. Prussiate of potash throws down vestium in milk-white 
flocks. 
In this property, vestium agrees with several metals, besides 
the easily soluble ones. But the property distinguishes oxide 
of vestium from lime. 
3. Sulphuretted hydrogen both in the liquid and gaseous 
state precipitates vestium of a dark reddish-brown colour. No 
precipitate falls if the solution or the reagent contains a slight 
excess of acid. When the precipitate is separated and in quan- 
tity, it appears black; but when floating in water, it has a 
brownish colour with a tint of red. The alkaline hydrosulphurets 
throw down vestium black. é 
By these properties, vestium shows its metallic nature and its 
difference from all other metals, except nickel and cobalt; for 
both these metals exhibit the same properties with sulphuretted 
hydrogen as vestium does. This is the reason why I could not, 
by precipitating with sulphuretted hydrogen, free vestium from 
these two metals; which I at first erroneously ascribed to their 
salts adhering to the precipitate. 
M. Proust indeed has affirmed, and the statement is com- 
monly believed, that nickel and cobalt are not precipitated from 
their solutions by sulphuretted hydrogen gas. But the assertion, 
if taken in all its generality, is not correct. The following seems 
to be a correct statement of the phenomena. Neither of the 
metals is precipitated from acid solutions by sulphuretted 
hydrogen gas ; but both of them are precipitated by that gas 
from neutral solutions. But the precipitation in this last case 
soon reaches its limit; for the base being partially separated 
from the acid, this last begins to predominate in the liquid; and 
when the acidity has advanced to a certain point, all further 
precipitation is prevented. 
+ The precipitation of vestium by sulphuretted hydrogen is by 
