466 Mr. Henry on the Natural Hijlory , &c. 
Porcelain, and without the lead adhefion to the 
crucible.* 
This experiment Teems to coincide with that 
of Bergman, but to differ, in Tome degree, from 
that related by Macquer. Mr. Magellan, whom 
we have very defervedly - ranked among our 
honorary members, has lately favoured me with 
an account of fome curious experiments, made 
in London, which may ferve to clear up this 
point. 1 fhall therefore comply with his requeft 
to lay an extract of his letter before the Society; 
and then beg leave to add a few remarks on the 
fubjedt, and on fome other of the chemical pro¬ 
perties of Magnefian Earth, which are either un¬ 
known or undecided. 
“ I "have a fadt,” fays Mr. Magellan, “ to 
* c relate, which may be agreeable to you, con- 
< c cerning the portion of Calcined Magnefia you 
“ favoured me with. On my return to London, 
“ many experiments were making with a mod 
“ powerful burning lens, executed by Mr. 
<c Parker. Among thefe, was a very (triking one, 
“ which puzzled me much, made with Calcined 
“ Magnefia, caked, by preffure, into a cubic 
form, of i of quarter of an inch per fide^ 
This, expofed to the focus of the lens, W23 
“ reduced from tVo to t®o on each fide of the 
cube. On hearing this I was (truck with the 
<c fadt, which is contrary to the known property 
* Opufcules Chymiques et Phifiqucs de M. T. Berg¬ 
man, traduits par M. de Morveau, tome. I, p. 398. 
“ of 
