266 
Mortar . 
For patents relating to white lead see Repertory of Arts, 
Old Series, voL 3. p. 225, voh 5„ p. 249, voh 8. p. 378, 
voL 11. p. 38. New Series, vol. 6. p. 169, voL 7. p. 399. 
For the manufacture of sheet lead, see Repertory of Arts, 
New Series, voL 1. p. 133. For refining lead, Xb. New 
Series, vol. 2. p. 72, vol. 4. p. 194. T. C. 
MORTAR. 
On the Cement used in building , called Mortar . f By the 
Editor ,J 
Having finished the article Bricks, I proceed to that of 
mortar. 
Limestone, when subjected to chemical experiment, is 
found to contain from 43 to 44 per cent, of carbonic acid 
gas, formerly called fixed air. It contains also a small 
quantity of water. When pure limestone is burnt in a 
lime-kiln in the best manner, one ton, or twenty hundred 
weight of 1 12 lb. to the hundred weight, will yield, about 
111-4 hundred weight of good lime. The loss is, partly 
water; but chiefly carbonic acid gas. (Watson.) 
A bushel of chalk will weigh 86 1-2 lb. A bushel of 
lime made from that chalk weighed when warm from the 
kiln, 66 1-4 lb. which is greatly too much : for a ton of the 
'"same chalk when well burnt, produced but 11 cwt. 1 qr* 
191b. of lime. If burnt in the best manner, it ought not 
to produce more than 11 cwt. of lime. Ib* 
A hard limestone from Lancashire weighed 1841b. to 
the bushel, up-heaped. At Clitheroe in Lancashire the 
limestone up-heaped, weighs 147 lb. to the bushel. If 
the produce be more than 11 hundred weight or there- 
about from the ton, either the limestone is impure, or the 
