286 Sugar of Poiatoe 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 cyhnder 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 drum 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 a fine pum.ice, ' 

 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 repair, 

 and apparently was capable of grinding one thousand bushels more 

 without impairing its efficiency. 



The next step, in the operation, was to convert the starch into 

 sugar. For this purpose a strong wooden vessel was formed, capa- 

 ble of sustaining a pressure of ten pounds to the square inch, and of 

 the capacity of four hundred gallons. This vessel was ch?a'ged with 

 two hundred and twenty five gallons of water, being the necessary 

 quantity for dissolving six hundred pounds of wet starch, equal to 

 three hundred and seventy pounds of dry starch, the amount com- 

 monly converted at each operation. A steam pipe from a strong 

 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 tempera- 



