3808. 
These differences neither, however, in- 
flucnced the progress, the periods, nor 
the essential characters of the vaccine 
eruption. 
They were only manifested: 1st. In 
the shape of the pustule, which became ex- 
tended, and ran into the small pustules 
surrounding it, so that the regular form 
of the principal pustule was.lost, as well 
as the depression which appeared in the 
middle, at the time of its formation, 
2d. In the nature of the scab, or crust, 
which succeeded to the pustule. It was not 
smooth, and of a shining brown colour 
like the seal usually observed in vacci- 
nated patients, but of an irregular shape, 
like the pustule from which it proceeded, 
and left in the skin a more or Jess deep 
pit, which was, however, soon filled up. 
And lastly, in the eruption of pustules 
on other parts of the body, which ap- 
peared at the moment when the areola 
was formed round the principal pustule. 
These irregularities were epidemic 
throughout the territory of Lucca. 
The test of variolous inoculation, to 
which several individuals submitted, who 
had undergone the irregular vaccine 
pock demonstrated, that this irregularity 
did not destroy the preservative property 
of vaccination. 
The third department of the History of 
Nature, or that which treats of minerals, 
has been lately, we are informed, en- 
riched with a very interesting fact. 
M. Vauquelin has discovered the pre- 
sence of platina, in the celebrated silver 
mines of Guadal-Canal, in Estremadura. 
He found this metal, which is so valuable 
in most of the arts, here, as in the mines 
of Peru, combined with a great variety 
of different substances, as silver, copper, 
iron, antimony, arsenic, lead, and sulphur, 
sometimes even amounting to one-tenth 
of the mass. 
The same chemist has likewise made. 
some experiments of the highest impor- 
tance, on the refining of iron ore. 
France produces ‘abundance of excel- 
Jent iron; but it is well known that it 
differs very materially in quality, accord- 
ing to the mines whence it is drawn, and 
the forges wherein it is prepared. 
M. Vauquelin has lately undertaken a 
series of interesting and important expe- 
riments, in order to-discover the causes 
of this difference: With this intention, 
he not only analyzed the ores and the 
melted metal, but also the fluxes which 
are added to it, and the scorix, or other 
refuse separated from it. In conse- 
Montuty Mac., No. 165. 
Proceedings of Learned Socteties. 
specting 
~ 
S71 
quence of this examination, he discovered 
in the slimy iron ore of Burgundyand of 
Franche-Comté, besides the oxide of iron, 
silica, alumine, line, magnesia, oxide of 
manganese, and chromic acid. 
M. Vauquelin atiributes the inferior 
quality of certain kinds of iron to some 
remaining nuxture of the chrome, phos- 
phorus, and magnesia; and he hence ob- 
serves, that it should be the first care of 
refiners to free this metal trom such in- 
jurious substances. Besides these valu«’ 
able practical remarks, this ingenious 
chemist, (from finding that the composi- 
tion of this mineral, but more particularly 
of the sublimed matter adhering to the 
furnaces, greatly resembles that of at- 
mospheric “stones) has taken occasion to 
Sugyest a new and plausible theory re- 
this wonderful phenomenon, 
The only difference between the sublimed 
matter and these stones, consists im 
nickel being found ‘in the latter. 
As a great portion of this sublimed 
matter does not adhere to the furnace, 
but is carried to a great height in the at- 
mosphere, M, Vauquelin thinks it possi- 
ble that it may concur towards the for- 
mation of aérolites. The only difficulty 
attending this explanation, seems to be 
how these sublimed metals could enter 
into combination in the atmosphere, so 
as to form such large masses, as many of 
the stones in question. 
From the present report, it also aps 
pears, that the subject of iron-mines has 
been treated under another point of view, 
by Messrs. Descostils and Hassenfratz. 
These ingenious mineralogists have found 
from repeated trials, that the mineral 
usually termed spathic iron, is extremely 
variable in its degree of fusibility, and 
that it produces 4 metal of very different 
qualities. M. Descostils is of opinion, 
that the difficult fusibility of some spe- 
cimens proceeds from the magnesia which 
enters ito their composition, since all 
the infusible kinds of spathic iron he had 
analysed, contained this earth; and even 
when he added a portion of it to fusible 
specimens, it had the etfect of depriving 
them of this quality. Hence he explains 
the effect of exposure to air and humi- 
dity im facilitating the fusion of these 
minerals, from sulphuric acid being formed 
by the decomposition of pyrites, and dis- 
solving the magnesia. M. Hassenfratz, 
on the contrary, rejects*tius theory, and 
contends that he has examined several 
kinds of infusible spathic iron, which 
contained no magnesia in their compo- 
4 ¥ sition 5 
