ON THE FECULA OF POTATOES, &C. ] g3 



periinents two assertions, which were there made, viz. that ^j^g^ exuerl- 

 the quantity of fecula procured from the solanum tubero- meats. 

 sum is influenced by the mode of operating, and by the pre- 

 cise state of dryness of the fecuia at the time it is weighed. 



In August last, 1000 grains of the young roots of the po- Hundred eyes 

 tato called hundred eyes, which had not arrived at their full potato, 

 growth, were grated, and, by the same manipulation as was 

 employed in the former experiments, aiiorded 



Grains. 



Fine white dry fecula 99 



Discoloured fecula 6 



Dry pulp 71 



Water, soluble mucilage, and extractive matter 817 



1000 



The same quantity of these roots being grated and repeat- 

 edly triturated in a mortar, with frequent ed ulceration, and 

 pressing the pulp with the hands, afi'orued 



Fine white dry fecula Ill 



Discoloured fecula 20 



Diy pulp 44 



Water, soluble mucilage, und extractive matter 825 



1000 



Thus by greater care and attention bestowed in the last Difference of 

 process, we gained twenty-six grains more fecula from one ^i.^_^j^"^^^^^"* 

 thousand grains of the fresh root, than we procured by the care. 

 first method of operating. 



When the fine white fecvda procured in the last experi- ^27 gi-s appa- 

 ment was at first separated, it was placed in a window facing rently dry lost 

 the south for two days, exposed to the air, and frequent 

 sunshine, until it felt and appeared perfectly dry, it then 

 weighed 127 grains; but being farther dried upon an iron 

 plate, with a gentle heat for two hours, and put into the ba- 

 lance while it was sensibly warm, it weighed 111 grains. 



It therefore lost 16 grains in weight after it appeared to and then ab- 

 be quite dry. It was afterwards placed in a cellar for twelve sorbed 29 from 

 '■ "^ , the air of a eel- 



hours, jar. 



