y^ QUANTITY OF FECULA IN THE POTATO. 



mer^P^s approximations toward tlie truth, or at most, a# 



showing tlie relative quantity of fecula^ afforded by the dif- 



feveijt varieties which were operated upon. 



Cautions. Whf^h experiments are made in the large way, with the 



fresh potato, the different degrees of moisture, which the 



roots may possess, will materially influence the results ; so 



will the form of the grater, and the force which is employed 



in grating them. Therefore when great accuracy is required, 



the potatoes should be sliced, dried, and ground to meal, 



before being subjected to experiment. 



Fecula most Perhaps the gfeatest quantity of fecn'a may be procured 



^."" '^""Itlv" ^" ^'^^ autumn, as soon as the potatoes are dug up; for 



changing to those that have been preserved through the winter are so 



sacchannt mat- jjg j^ ^ |.y^g jj^ ^] spring, that they then contain 



ler in spring. *- = . i 5' J 



more of the saccharine matter than they do in the autumn : 



and this is produced at the expense of the fecula, for it is 

 probable, that, as the fecula absorbs oxigen and hidrogen, 

 it parts With a portion of its carbon, and is thereby converted 

 into sugar. 

 Potato attracts Another circumstance, which may very mucli affect the 



moisture from apparent quantity of fecula, is its precise state of dryness 

 the atmosphere. ' ^ . ' ; . ' 



when weighed ; for it quickly attracts moibture from the at- 

 mosphere, and therefore should always be v/eighed at a cer- 

 tain temperature, in a dry room. 

 Fecula dried In the following experiments, the fecala, after being dried 

 m a roa.ter. j^^ ^|^g ^p^^^ ,^j^^ ^^^g placed for soaie liours in a Rumford 

 roaster, moderately warm, and vv-eighed as soon as it was 

 taken out. This perhaps is one reason why my produce is 

 generally below .that of Dr. Pearson, which he com muni- 

 Skin of the no- cated to the Board of Agriculture, as well as by his not 

 tato inc u e . ^^^\^^^ ^j^^ pi^jn of the potatoes in his experiments, as I did 



in those which follow. 

 Dr. Pearson's From Dr. Pearson's account we learn, that 3500 grains 



experiments ^f fiesh potato root, commonly called the white kidney, 

 -svith the k:d- ,.,.,, . ^ . 



ney potato. bemg dried, leave 1000 grains : 



That 100 parts of the fresh root, deprived of skin, affori 



1. Water 68 to 72 



2, J^Iegl 32 to 28 



100 100' 



The 



