THE 
EMPORIUM 
OP 
ARTS AND SCIENCES. 
Yol. &.] February, 1813. [No. 10. 
NO. 48. 
Memoir on the Discovery of a Factitious Puzzolana , 
'presented to the French National Institute , by M. 
Dodun, Engineer in Chief of Bridges and Highways 
in France.* 
THE deposited dust of ancient volcanic substances, 
has been long used in Flanders, and the adjacent coun- 
tries, as a substitute for the Italian puzzolana, under the 
name of trass , or ashes of Tournai. 
M. Faujas has proved by decisive experiments, made 
by order of government, that certain lutulent eruptions 
of ancient volcanoes at Yivarais, had the same qualities 
as the puzzolana of Italy, and might be used instead of 
it. M. Bagge, a Swede, is also known to have composed 
an artificial puzzolana cement, with a black, hard, and 
slatey schist; but until 1787, no one ever thought that 
the territory of France contained in abundance non- 
volcanic substances capable of taking place of the Italian 
puzzolana with economy and advantage. 
* Nicholson, vol. 12, p. 33L From the Journal de Physique, tom. 61, 
Yol. ii, Gg 
