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1 believe that the same proportion of almost any oxyd 
of iron, or of manganese, or even of the common smithy- 
slack of a blacksmith’s shop, well sifted* will answer the 
same purpose. So will Basalt, burnt and ground, 
Loriot’s patent for water cement, consists alone in 
the mixing of ground fresh burnt lime with common 
mortar, which is manifestly imperfect and unscientific ; 
inasmuch as old effete mortar, can never be equal to fine 
quartzose sand. 
Higgins’s patent stucco, is fresh, well-burnt lime one 
part ; sand half fine, and half rather coarser, well washed 
from dirt and clay, six or seven parts ; I think six parts 
best. Bone-ashes ground tolerably fine, equal to one 
fourth of the lime. The water used must be lime water. 
For inside work the bone-ash may be in proportion of a 
third of the lime. 
Johnson’s patent stucco, was characterized merely by 
an admixture of blood with the water used to make up 
the cement. 
I regard Higgins’s as the best. I have seen them, all 
both fresh used, and many years afterward. T. C. 
PERKIN’S IMPROVEMENT ON WATER MILLS, 
WITH A PLATE. 
THE subscriber has recently obtained a patent for an im- 
provement in water-mills, which, from actual experience, has been 
found to be of great importance ; it consists in the complete re- 
moval of all the inconveniences heretofore experienced from back 
water. 
It is a well known fact, that in most situations it has been found 
necessary to place water-wheels from one to three feet higher 
than they would be, were it not requisite to avoid the back water, 
occasioned by the freshets and high tides. In nearly all cases; 
Vol. III. M m 
