1804] 
of nickel, or to that of artificial pyrites. 
The texture of this fubftance is granu- 
lated, and not very ftrongly connected : 
when pounded, it is black. This py- 
rites is not attraétable by the magnet. 
The third of thefe fubftances confifts 
of {mall particles of iron, in a perfeétly 
metallic ftate, fo that they may be eafily 
flattened or extended by means of a ham- 
mer. Thefe particles give to the whole 
ma{s of the ftone the property of being 
attractable by the magnet. 
The three fubftances juft defcribed, are 
united together by means of a fourth, 
which is nearly of an earthy confiftence. 
The black cruft with which the furface 
of the ftones is coated, although it is fo 
thin, emits bright fparks when ftruck 
with feel. It may be broken by a 
ftroke with a hammer, and feems'to pof- 
fefs the fame properties as the black ox- 
ide of iron. When breathed on, they do 
not emit an argillaceous {mell: the fame 
remark may be applied to all the others. 
The f{pecific gravity of the Benares ftones 
Is 335480 
The conftituent parts of the ftone from 
YORKSHIRE are exaétly the fame as thofe 
of the ftones from Benares, but it differs 
from them (1) In having a finer grain. 
(z.) The particles are lefs globular, of 
an irregular fhape, and in general of a 
fmaller fize. (3.) The proportion of mar- 
tial pyrites is Jefs; that of the iron ina 
metallic {tate is much greater. The fpe- 
cific gravity is 3,508. 
The grain of the ftone from SrENNA 
was coarfe, fimilar to that from Benares ; 
in it might be perceived the fame grey 
globular bodies, the fame kind of martial 
pyrites, and the fame particles of iron in 
the metallic ftate. ‘The proportion of 
thefe laft was much lefs than in the ftone 
from Yorkfhire ; but rather greater than 
in the ftones from Benares. The black 
craft which covered the ftone was rather 
thinner than that of the ftones already de- 
fcribed ; and feemed to have undergone a 
kind of contraction, which had produced 
in it @ number of fifflures or furrows, 
tracing upon the furface the appearance 
of compartments, fimilar, in fome mea- 
fure, to what is obferved in the fiones 
called Septaria. The fpecific gravity of 
this ftone was 3,418. 
The internal ftruéture of the ftone 
from Bouemia is very fimilar to that 
, from Yorkfhire, Its grain is finer than 
that of the ftones from Benares, but in 
other refpects it is very fimilar to them. 
On Stones, Ec. faid to have fallen from the Clouds. 
535 
From the others it differs in the following 
particulars. (1.) The particles of py- 
rites cannot be feen without a lens. (2.) 
It contains a much larger quantity of 
iron in the metallic ftate, equal to a fourth 
of the whole. (3.) Many of the parti- 
cles of iron have undergone an oxidation 
at their furface, which, by adding to the 
bulk, and the force of a€tion, of the part 
we have defcribed as ferving by way of 
cement to the other conftituent parts of 
the ftones, has occafioned a greater de- 
gree of adhefion between thefe parts, and 
has rendered the fubftance of the ftone 
more compact. 
The great quantity of iron in the me- 
tallic ftate which this ftone contains, 
added to its greater compactnefs, makes it 
capable of receiving a flight degree of 
polith ; whereas it is impoffible to give 
any polifh to the others. When poiithed, 
the iron becomes very evident, in the po- 
lithed part, appearing in the form of 
fmall fpecks, almoft clofe to each other. 
which have the colour and luftre peculiar 
to that metal. The fpecific gravity of the 
ftone is 4,281. 
It is eafy to perceive from the fore. 
going defcription, that thefe ftones, al. 
though they have not the fmalleft fimi- 
larity with any of the mineral fubftances 
already known, have a very peculiar and 
ftriking analogy with each other. This 
circumitance renders them worthy of the 
attention of philofophers ; and naturally 
excites a defire of knowing to what caufes 
they owe their exiltence. 
According to Mr. Howard’s analyfis, 
which appears to have been condudted 
with confiderable care, all thefe ftones 
confit of filica, magnefia, oxide of iron, 
and oxide of nickel, combined in nearly 
fimilar proportions. The refult. of this 
examination differs from the analyfis made 
by the French academicians, of the ftone 
prefented to them by the Abbé Bachelay, 
as well as from that made by Profeffor 
Barthold of the ftones of Enfitheim. It 
is at variance with thac of the academi- 
cians, inafmuch as they found neither 
magnefia nor nickel. It differs from that 
of Mr. Barthold, as hé did not find 
nickel, but difcovered fume lime, with 
17 per cent. of alumina. But notwith- 
ftanding thefe variations, the mineralo- 
gical defeription of the French academi- 
cians, of M. Barthold, and of the Count 
de Bournon, all exhibit a ftriking con- 
formity of chara€ter common to cach of 
thefe ftones ; and it is the decided opinion 
322 of 
