Starch . 
145 
fating it from muriat of tin, or by calcining it by diges- 
tion with nitric acid. In London there are persons who 
deal in white enamel, for the use of clock and watch mak- 
ers, and who make a trade of calcining their tin which is 
the chief part of the composition ; the flux being borax 
and flint glass, and I believe a little white arsenic. 
Either of these formulas, are to be well mixed and then 
fused. While in fusion they are to be poured out on a 
dean iron or copper plate, and when cold, ground to a 
powder, passed through a sieve, again levigated with 
water, to which mucilage is to be added to keep 
the powder suspended. With this paste the inside of the 
vessel is to be smeared : when dry to be again slightly 
smeared over : then exposed to a heat sufficient to melt 
the composition ; the vessel thus coated must be cooled 
gradually. 
I have used of these vessels with great satisfaction. 
t. c; 
STARCH. 
On the making of Starch. By Mr. James Graham, of Berwick « 
ufion-Tweed . 
STARCH maybe made from a variety of articles potatoes, 
in particular, will yield a considerable quantity ; but the great la- 
bour attending grinding or grating them down has hitherto pre- 
vented any great quantity of starch being made from that vegetable. 
When the potatoes are grated down, they do not require to be laid 
in steep to ferment after the manner of flour, but must be immedi- 
ately strained through a sieve ; and if the potatoes are of a good 
quality, the starch will settle to the bottom almost instantly : in- 
deed the operation of straining after the potatoes ard grated down 
cannot be performed too quickly. The produce, however, even 
from the best, is far less than most people would imagine ; the* 
best potatoes I ever used, only produced 4 or 4^ stones of starch 
from 40 stones of potatoes. 
Vol. III. T 
