286 Sugar of Potatoe Starch. 
much charged with lead, of crystallizing into a firm, tough, white 
mass, with minute indistinct crystals, acquiring weight by absorbing 
water of crystallization from the atmosphere, and uniformly bursting 
the earthen vessels in which it had been crystallized. ‘The conver- 
sion of the starch to sugar was always completed in about three hours. 
When the heat was continued eight or ten hours, the sugar was much 
more contaminated with lead, and crystallized more promptly, but 
acquired, from the continuance of the heat, no increase of saccharine 
properties. 
After a sufficient number of experiments had taught the way, the 
following apparatus, and mode of working were adopted, and, as it 
appeared, seemed scarcely to require, or be susceptible of improve- 
ment. 
For grinding the potatoes, the following very ingenious and effi- 
cient contrivance was devised, and executed by Capt. Potter. He 
obtained a true, smooth cylinder of hard wood, two feet long, and 
one foot in diameter, provided with gudgeons and a whirl. The face 
of this cylinder was covered, by winding and nailing upon it long strips 
of sheet iron, about two inches wide, punched full of holes, so as to 
give them a strong, rough, grater surface. This cylinder or grater 
was so hung, as to constitute the anterior side of a box or hopper; 
and made to revolve very near the anterior edge of its bottom, being 
driven by a band from the dram of a waterwheel. On filling the 
hopper with potatoes, and giving to the grater the necessary motion, 
the potatoes were reduced with surprising rapidity to @ fine pumice; 
from which, by the aid of a seive and water, the starch, in great pu- 
rity, was readily obtained. This apparatus ground three thousand 
five hundred bushels of potatoes, without requiring the least repall; 
and apparently was capable of grinding one thousand bushels more 
without impairing its efficiency. ai 
The next step, in the operation, was to convert the starch mto 
sugar. For this purpose a strong wooden vessel was formed, cap* 
ble of sustaining a pressure of ten pounds to the square inch, an¢ © 
the capacity of four hundred gallons. This vessel was charged with 
two hundred and twenty five gallons of water, being the necess#ty 
quantity for dissolving six hundred pounds of wet starch, equal 
three hundred and seventy pounds of dry starch, the amount com 
monly converted at each operation, A steam pipe from a stt0"8 
sheet iron boiler, was continued to the bottom of the tub or convert 
er, and the steam let into it until the water had acquired a tempere- 
