oH 
NEVVIIAVEN C El EES. 
Aliiniine - 30 
Sulpluiric acid, ^4 
AVater - 45 * 
Crystals of gypsum are frequently disseminated 
through the masses of alumine, and the two sub- 
stances enter into various states of combination, 
sometimes giving rise to specimens that are semi- 
translucent. Clialk flints, indurated ochraceous 
clay, and other extraneous bodies, are also occa- 
sionally enveloped. 
From the experiments of the late Dr. Clarke, it 
appears that the purer masses of aluminite are des- 
titute of sulphuric acid, and consist simply of water 
and aluminous earth. Hence a susjiicion has arisen 
that the sulphuric acid, in the examples analyzed 
by Strom eyer and Dr. Wollaston, may have ori- 
ginated from the presence of gypsum : this, how- 
ever, is not the case ; since in many specimens it is 
evident that the sulphate of lime has been decom- 
posed, and the sulphuric acid, entering into com- 
bination with the alumine, has formed a true sub- 
sulphate. 
The hydrate occurs in friable masses, of the 
colour and consistence of magnesia : it adheres to 
the tongue, and may be reduced to powder be- 
tween the fingers. In this respect it differs from 
the subsulphate, which possesses considerable hard- 
ness, and is susceptible of a fine polish, t 
* Phillips’s Mineralogy, 2d edition, 1819, p. 111. 
-f- In the elegant coinpendinni of geology, inserted in Professor 
Brand’s Manual of Chemistry, are the following observations on this 
subject : — 
“ In the cliffs at Newhaven, on the Sussex coast, a very curious 
series of changes is going on. A stratum of marl containing decom- 
