£37" 3 
N° VL 
Defcription of a new Stove for burning of Pitcoal, and 
confuming all its Smoke. 
BY DR. B. FRANKLIN. 
Senne A eee ne the end of the laft century an 
ingenious French philofopher, whofe name 
{am forry I cannot recollect, exhibited an experiment to 
fhow that very offenfive things might be burnt in. the 
middle of a chamber, fuch as woollen rags, feathers, &c. 
without creating the leaft fmoke or fmell. The 
machine in which the experiment was made, if I Pelt 
remember right, was of this form, made of plate ~ 
iron. Some clear burning charcoals were put into the 
opening of the fhort tube A, and fupported there by the 
grate B. The air as foon as the tubes grew warm would 
afcend in the longer leg C and go out at D, confequently 
air muft enter at A defcending to B. In this courfe it muft 
be heated by the burning coals through which it paffed, 
and rife more forcibly in the longer tube in proportion to 
its degree of heat or rarefaGtion, and length of that tube. 
For fuch a machine is a kind of inverted fyphon; and as 
the greater weight of water in the longer leg of a common 
fyphon in defcending is accompanied by an afcent of the 
fame fluid in the fhorter; fo, in this inverted fyphon, the 
greater quantity of levity of air in the longer leg, in rifing 
is accompanied by the defcent of air in the fhorter. The 
things to be burned being laid on the hot coals at A, the 
{moke muft defcend through thofe coals, be converted into 
flame, which, after deftroying the offenfive fmell, came 
out at the end of the longer tube as mere heated air. 
Whoever 
