36 Whitney's Chemical Examination 
Art. Ill. — Chemical Examination of some American 
Minerals. By J. D. Wurrney. 
I. FIBROUS HYDRATE OF MAGNESIA, ee OF F NUTTALL, 
THOMSON AND CONN 
Tur fibrous hydrate of magnesia which was first discovered 
and named by Nuttall, without analysis, but which was con- 
sidered by him as hydrate of magnesia, has been twice sub- 
jected to analysis with very discordant results. ‘Thomson, 
having examined a specimen which contained a portion of 
silica, or silicate of magnesia, mechanically intermixed, gave 
for this mineral the formula 
Mg Si + 2 Mg H; 
his analysis having given him about twelve per cent. of silica. 
Connell has more recently analyzed the same mineral, and, 
happening to have a specimen which contained no silica, but 
a considerable quantity of carbonate of magnesia, also me- 
chanically intermixed, he gives as the result of his analysis 
the formula 
H + Mg e H; 
a highly Werde die: 
I have examined a specimen of this mineral from the cab- 
inet of F. Alger, Esq., and find, that when perfectly pure, it 
contains neither silica nor carbonic acid, but that it isa fibrous 
hydrate of magnesia, though it often occurs mixed with the 
silicate and carbonate of magnesia. If a few fine fibres of 
the mineral be placed in dilute acid, the effervescence will be 
found to be but momentary, and confined to the extremities 
of the fibres, where they were in contact with the gangue ; as 
soon as the adhering impurities have been removed the min- 
eral dissolves without effervescence. 
The following results of an analysis will show conclusively 
that the nemalite is essentially hydrate of magnesia, oF 
i 
