Factitious Puzzolana . 
properties of that of Italy, without its faults. At this 
time I determined to propose its use in the public works, 
and demanded that comparative experiments should be 
made between it and the Italian puzzolana, in presence 
of the commissaries of the province of Languedoc, and of 
the directors of the canal which joins the two seas. Great 
blocks of Baton composition made with both cements, 
were thrown into the reservoirs adjacent to the lock of 
Saint Rocli, at Castlemandery, being first plaistered over 
with the respective compositions. 
Six months after, the water was drawn off from the 
bodies of masonry, and it was then seen that the factitious 
puzzolana had acquired a solidity at least equal to that 
of Italy. The plaister made with the Italian puzzolana 
was cracked and chapped, but that formed from the fac- 
titious kind had entirely preserved the unity of its sur- 
face. 
The states of Etats of Languedoc altogether convinced 
of the authenticity of this discovery, by the results of the 
comparative trials of both kinds of cement which they 
had seen, and by the certificates of their commissaries, 
and persuaded of the great advantage it would be to 
France, decreed in 1789, in their last meeting, that the 
factitious puzzolana should not only be used instead of 
the Italian in the works under their direction ; but more- 
over; that it should be demanded in favour of the author 
of it, as a testimony of public gratitude, that govern- 
ment should authorize the free circulation of it every 
where. 
The great consumption of this factitious puzzolana 
obliged me to extend its manufacture, I formed a part- 
nership with the proprietor of the ground. The founda- 
tion of an establishment on a great scale was laid at the 
mountain itself where the materials were found. The 
works carried on in its vicinity were likely to farther re 
