EXTRACTS 
FROM COMMUNICATIONS MADE TO THE SOCIETY. 
I. On an Artificial Formation of Plumbago. 
EXTRACT of a Lerrer from James ALDERSON, Esq. to the 
Rev. Professor Cummine. 
[Read February 21, 1825.] 
Tue accompanying specimen of Carburet of Iron formerly 
composed part of a groove in which a patent perpetual log was 
made to slide. It was originally cast iron, and was nailed to 
the coppered stern post of the ship Zoroaster, of the port of 
Hull. 
On the return of the ship from India, after an absence of 
about nine months, it was found as it now remains, converted 
ito Plumbago, having lost very considerably in weight, but 
having perfectly retained its original form. 
Pembroke College, Cambridge, 
Jan. 22, 1825. 
Remarks py Proressor Cummina. 
Oxe of the most striking properties of this artificial Plumbago, is its 
extreme levity as compared with that of the substance from which it 
is obtained, 
SL 
