328 Pf Lawrence Smith on Meteorites. 
in this way there will be no difficulty in tracing the same signa- 
ture on them all, endorsing the above as their true character, and 
almost serving to tell us whence they came. They may emphatic- 
ally be said to have been linked in their origin by a chain of iron: 
There is one mineral which there is every reason to believe 
constantly accompanies the metallic portions, and which may be 
regarded as a most peculiar mark of difference between meteor- 
ites and terrestrial bodies. Jt is the mineral Schreibersite (see 
first part of this memoir) to which the constant presence of phos- 
phorus in meteoric iron is due. This mineral as already re- 
marked has no parallel on the face of the globe, whether we con- 
sider its specific or generic character, there being no such thing 
as phosphuret of iron and nickel or any other phosphuret found 
among minerals. These facts render the consideration of Schrei- 
bersite one of much interest, running as it probably does through 
all meteorites, and forming another point of separation between 
meteorites and terrestrial objects. : 
Another striking similarity in the composition of meteorites 1s 
the limited action of oxygen on them. In the case of the purely 
metallic meteorites we trace an almost total absence of this ele- 
ment. In the stony meteorites, the oxygen is in combination with 
silicon, magnesium, &c., forming silica, magnesia; &c., that com- 
ine with small portions of other substances to form the predomin- 
ant earthy minerals of meteorites. When iron is found in com- 
bination with oxygen, it is found in its lowest state of oxydation 
as in the protoxyd of the olivine and chrome iron, and as mag- 
netic oxyd. i aia 
Without going further into detail as regards the similarity of 
composition of meteorites, they will be seen to have as strongly 
marked points of resemblance as minerals coming from the same 
mountain, I might almost say from the same mine, and it is not 
asking much to admit their having a common centre of origin avi 
that whatever the body from which they originate, it must con- 
tain no uncombined oxygen and I might even add none in the 
form of water. eh 38 
What is this centre of origin? Physies does not point it out, 
and although the chemist cannot explore the elementary constitu 
tion of any other great celestial bodies than the earth, he can ex 
amine those smaller celestial masses which come to the earth and 
from his results stand on a firmer basis for theoreticakconclusions- 
Origin of Meteoric Stones.—In taking up the theoretical con- 
siderations of the origin of meteoric stones, it is of th utmost 
consequence, to reflect well before we confound shooting stars 
and meteoric stones as all belonging to the same class of 
eS ; 
a view entertained by many distinguished observers. It is doubt- 
f eir having bec confounded that but 
eek a origin of these 
less owing to the fact of their ha 
made in 
