) 
* of the Ancients, 181 
se a 15, water 14, hai 12, lime 3, ironi. With this 
earth, which is found near Cafteldelpiano in the territories 
of Sienna, M. Fabbronicompofed bricks which, either baked 
er unbaked, floated in waters The baked were in nothing 
different from the’ unbaked, but in the fonorous quality 
which they acquired. Thefe bricks refift water exceedingly 
w ell, and unite perfectly with lime: they are fubjeéct tq no 
alteration either by heat or cold; and about a twentieth part 
of argil may be added’ with advantage to their compofi- 
tion, without depriving them of the property of floating. 
M. Fabbroni tried their refiftance, and found it very little 
inferior to that of common bricks; but it is much greater in 
proportion to their lightnefs. One of thefe bricks, fever 
inches in length, four and a half in breadth, and one inch 
eight lines in thicknefs, weighed only 14 ounces; whereas 
a. common brick weighed ie pounds 63 ounces. 
’ Foffil meal ds abundant in Tufcany. The method of make 
ing thefe bricks differs little from that of common. bricks : 
one man may make about a hundred ef them in a day, 
They may be of very important benefit in the conftruction 
of reyerberating furnaces; as they are fuch bad conduétors 
of heat, that a perfon may bring one half of them to a 
red heat, while the other is held in the hand, They may 
be employed alfo for buildings that require to be light; 
for conftructing cooking places on board fhips; and alfo 
floating batteries, the parapets of which, if made of thefe 
bricks, would be proof againft red hot bullets; and laftly, 
for conftructing powder magazines. The turrets which 
were raifed on the fhips of the ancients, adds M. Fabbroni, 
were perhaps formed of fuch bricks; and perhaps they were 
employed in the celebrated fhip fent by Hiero to Ptolemy, 
and which carried fo many buildings, confifting of porticoes, 
baths, halls, &c. ornamented with jafper and agates ar- 
Tanged in mofaic, ; 
N3 XIV. Ex- 
