Miner alogkai Description of some Aerolites. 
$dly y Some few metallic grains could be extracted with the 
magnet. These were examined, in order to find if nickel exist- 
ed in them, but none could be traced. 
4 thly, The great mass of the stone was a greyish ash-coloured 
powder, with very little cohesion. Under the blowpipe it pre- 
sented the following changes : 
It melted, without intumescence, into a black opake glass ; 
with borax, it melted with difficulty into a glass of a deep iron- 
colour ; with salt of phosphorus, the glass left a skeleton of silica, 
and was coloured with iron; witli soda, in small quantity, it 
gave a black globule ; if a greater quantity of soda was used, 
part of it went into the charcoal, and left a dark-brown un- 
melted scoria. 
These circumstances show that aerolites ought to be regarded 
and examined, not as homogeneous masses, but as a kind of 
compound rocks. Like other rocks of this description, they 
contain minerals of very different kinds, but commonly in a very 
minute state of division. The grey powder, which approaches 
more nearly in appearance to volcanic ashes than to any other 
substance, contains perhaps the rudiments of minerals which 
hav£ not yet had sufficient time or quietness to crystallize, or of 
which the crystals are so minutely mixed that we are not able 
to distinguish them from one another. This sufficiently accounts 
for the differences of proportion between the constituent parts of 
aerolites that have been analysed. 
Art. XXIV. — Observations on Double Stars. By M. Struve, 
of Dorpat, and Professor Amici, of Modena. 
M o Struve, an able and active astronomer at Dorpat in Li- 
vania, conceived the very laborious design of making a new ca- 
talogue of all the Double Stars which were observed about forty 
years ago, by Sir William Herschel, — to compare these observa- 
tions with his own, and especially to examine if any change had 
taken place in the relative positions of the two stars. 
M. Struve has published the results of part of this laborious un- 
dertaking, in his collection of Astronomical Observations ; but as 
we have not seen that valuable work, we have taken the following 
abstract of it from Baron Zach’s Correspondance Astronomique. 
3 
