182 Memoir of Alraham Gottlob Werner, 
terior substanee of the metal, which renders it uncertain when 
exposed to great degrees of heat ?—-There may be cavities m cast 
iron, but a boiler being proved to a strain beyond that it is to 
be exposed to by heat, the safety of the boiler is secured; for 
the temperature never can be at that point which will endanger. 
a fracture from that circumstance. 
Do you mean by that answer, to say that the rarefaction of 
the air in that cavity may not be so great by the heat as to oc- 
casion its bursting ?—It never can, because the air that produced 
that cavity was at a white heat at the time the iron closed upon 
it, and it never can be brought to such a heat. in working a 
boiler;—my opinion is, that by a very high proof at the com- 
mencement, and attention to it, you may always have a safe 
boiler of cast iron. 
[To be continued. ] 
XXVII. Memoir of AsRauam Gortion Werner, late Professor. 
of Mineralogy at Frieberg*. 
Asranam GorrLtos WERNER was born on the 25th of Sep- 
tember 1750. His father, who was inspector of an iron-work 
at Wehrau, on the Queiss, in Upper Lusatia, intended him from 
his early youth for a similar vocation. He first went to school 
at Bunzlau, where he received however but very scanty instruc- 
tion. In order fully to qualify himself for his intended pro- 
fession, he went first for some years to the Mineralogical Aca- 
demy at Frieberg, and then to the University of Leipsig, where 
he applied himself to the study of natural history more than to 
that of jurisprudence; and in respect to the former used to boast 
in later years of his intimacy with two distinguished naturalists 
of Leipsig, Mr. John Charles Gebler, and his brother John Sa- 
muel Traugott Gehler. Even while at the University he em- 
ployed himself on the doctrine of the external characteristics of 
fossils, in which a singular quickness of perception was of great 
use to him; and published there, in the year 1774, the well- 
known work (on the external characteristics of fossils) which is 
still considered as the basis of his whole oryktognosis, but of 
which he could never be induced to print a new and enlarged 
edition, because he feared disputes, and had not in fact con- 
cluded his researches. Soon after he was invited to Frieberg, 
to have the care of the cabinet of natural history there, and to 
read lectures upon it. Here his mind, which was early exercised 
in observation and classification, found the most welcome ma- 
terials. ere, daily extending the bounds of his science, and 
* From The Literary Gazette. , 
supporting 
