Dr. Wollaston on the Identity, &c. 247 
The resemblance was such in my first trials, as to induce 
me to endeavour to procure a further supply of columbium, 
and by application to the Trustees of the British Museum, I 
was allowed to detach a few grains from the original spe- 
cimen analysed by Mr. Hatchett. 
Notwithstanding the quantity employed in my analyses was 
thus limited, I have, nevertheless, by proportionate economy 
of the materials, been enabled to render my experiments suf- 
ficiently numerous, and have found so many points of agree- 
ment in the modes by which each of these bodies can or 
cannot be dissolved or precipitated, as to prove very satisfac- 
torily that these American and Swedish specimens in fact 
contain the same metal ; and since the re-agents I have em- 
ployed are in the hands of every chemist, the properties 
which I shall enumerate are such as will be most useful in 
the practical examination of any other minerals in which this 
metal may be found to occur. 
In appearance the columbite is so like tantalite, that it is 
extremely difficult to discern a difference that can be relied 
upon. The external surface, as well as the colour and lustre 
of the fracture, are precisely the same ; but columbite breaks 
rather more easily by a blow, and the fracture of it is less 
uniform, appearing in some parts irregularly shattered ; ne- 
vertheless, when the two are rubbed against each other, the 
hardness appears to be the same, and the colour of the scratch 
has the same tint of very dark brown. 
By analysis also, these bodies are found to consist of the 
same three ingredients ; a white oxide, combined with iron 
and manganese. 
Either of these minerals, when reduced to powder, is very 
K k 2 
