450 
General Science. 
out ail its denominations, never deviating above one-tenth of a 
grain from what it ought to have been, on the supposition of 
the pound being 7680 grains. There was another confirmatory 
circumstance. By James I. it was enacted, that the pint should 
contain 41 oz. Trone weight, of the clear water of Tay ; and 
by James VI., that the same measure should contain 55 oz. 
Scotch Troy of the water of Leith. Ifjhe water enjoined in the 
two cases had been the same, the pound Trone would have been 
to the pound Scotch Troy as 55 to 41 ; but the specific gravity 
of the water of Tay being to that of Leith as 100 to 103 nearly, 
it is a curious circumstance, that if this be taken into account, 
and the pound Scotch Troy reckoned 7680 grains, the pound 
Trone will turn out exactly 10,000 grains Troy. 
41. Blach Resinoiif! Varnish used at Silhet in Bengal. — This 
black varnish, celebrated for its lustre and durability, is prepa- 
red in the following manner : the nuts of the Semecarpus AnOf 
cardium^ and berries of the Holigarna longifolia^ having been 
steeped a month in clear water, are cut transversely and pressed 
in a mill. The expressed juice is kept for several months, and 
the scum taken off from time to time. The liquor is then decanted, 
and two parts of the one are added to one part of the other, to be 
used as varnish. Other preparations are sometimes employed, but 
the juice of the Semecarpus always predominates. The varnish 
is laid on like paint, and is polished by rubbing it when dry, with 
an agate or smooth pebble, — Quart. Journ. vol. x. p. 315, 316. - 
42. Manufacture of Catgut Strings, — The catgut strings used 
for harps and violins, are manufactured at Whitechapel, &c. of 
the peritorial covering of the intestines pf the sheep ; but have 
always been considered inferior to those exported from Italy. 
Dr MacCuIloch ascribes^ this superiority to the leanness of the 
Italian sheep, ^it is known,' that the membranes of lean ani- 
mals are stronger than those of fat ones ; and he suggests, that 
the catgut should be manufactured from the Welch Highland 
or Southdown breeds, in preference to those which, like the Lin-^ 
coin, are prone to excessive accumulations of fat. — Quart. 
Journ, vol. x. p. 267, 
43. On the Selection of Ice for Ice-houses. — M. Hemptinne of 
Brussels has shewn, that ice for summer use should be taken from 
^he river on 4 very cold day, and be exposed on t)ie foIIpFing 
