t 374 3 
XIX. On the Cause of the additional Weight which Metals ac~ 
quire by being calcined . In a Letter from George Fordyce, 
M.D. F.R.S. to Sir Joseph Banks, Bart. P.R.S . 
Read June, 21, 1792. 
SIR, 
Although many chemists are at present satisfied of the non- 
entity of what was formerly supposed to be a body, called 
phlogiston, and considered as an element contained in metals 
when in their metallic form, yet this supposition has inter- 
woven itself so much into chemistry in general, and has been 
so universally received, that it may not be superfluous to re- 
late the following experiments. If you are of that opinion, 
I shall be obliged to you if you will lay them before the Royal 
Society. 
When a man begins to make an experiment, however well 
digested his plan may be, he finds, when he comes to put it 
in execution, that he must make a great number of experiments 
before he can bring the fact to be proved, or disproved, fairly 
in issue ; if I may take a phrase from law, there are first many 
buts and rebuts. It has often been the practice to bring all 
this previous matter before the public. This practice may be 
very proper, although it does not seem so to me, and there- 
fore I have not troubled the Society with the difficulties and 
disappointments I have met with ; but have brought the 
simple experiments forward in such manner as that they can 
