Experimenis on Allanite. 285 
¢ipitated white by oxalate of ammonia and tartrate of pot- 
ash ; our oxide is not precipitated at all: oxide of cerium 
is precipitated white by hydro-sulphuret of ammonia; while 
our oxide is precipitated black : oxide of cerium is not pre- 
cipitated by zinc, while our oxide is thrown down black. 
There are other differences between the two, but those 
which | have just mentioned are the most striking. 
These properties induced me to consider the substance 
which I had obtained from the Greenland mineral as the 
oxide of a metal hitherto unknown; and I proposed to 
distinguish it by the name of junonium. 
In the experiments above detailed, I had expended al- 
most all the oxide of jwnonium which I had in my posses- 
sion, taking it for granted that I could easily procure more 
of it from the Greenland mineral. But, soon after, I was 
informed by Dr. Wollaston, to whom I had sent a speci- 
men of the mineral, that he had not been able to obtain 
any of my supposed junonium in his trials. This induced 
me to repeat the analysis no less than three times, and in 
neither case was I able to procure any more of the sub- 
stance which T have described above. Thus it has been 
out of my power to verify the preceding details, and to 
put the existence of a new metal in the mineral beyond 
doubt. At the same time, I nay be allowed to say, that 
the above experiments were made with every possible at- 
tention on my pait, and most of them were repeated at 
feast a dozen times. I have no doubt myself of their ac- 
curacy; but ihink that the existence of a new metal can 
hardly be admitted, without stronger proofs than the soli- 
tary analysis which I have performed. . 
5. The liquid, thus freed from iron and junonium, was 
- Super-saturated with pure ammonia. <A gravish-white 
elatinous matter precipitated. It was separated by the 
filter, and became gradually darker-coloured when drying. 
This matter, after being exposed to a red heat, weighed 
about 38 grains. When boiled in potash-ley, 4:1 grains 
were dissolved, of a substance which, separated in the usual 
way, exhibited the properties of alumina. 
6. The remaining 33°9.grains were again dissolved in mus 
riatic acid, and precipitated by pure ammonia. The precipi- 
tate was separated by the filter, and allowed to dry spontané-~ 
ously in the open air. It assumed an appearance very much 
fesembling gum-arabic, heing semi-transparent, and of a 
brown colour. When dried upoix the sand-bath, it became 
very dark-brown, broke with a vitreous fracture, and still 
tetained a small degree of transparency, It was tasteless, 
felt 
