18 



Maine Agricultural Experiment Station. 1919. 



the starch content. In years when there is potato blight vines 

 sprayed with Bordeaux mixture will usually outlive unsprayed 

 vines. In the comparison between unsprayed and sprayed from 

 the same fields the tubers from the sprayed portions averaged 

 to carry 19. 1 per cent starch and those from the unsprayed only 

 17.5 per cent. Also the dry matter in the tubers from sprayed 

 portions of the field averaged more than iy 2 per cent higher 

 than in the case of those from the unsprayed portions. 



Every experiment made at this Station has shown proper 

 spraying with Bordeaux mixture to increase the yield of mer- 

 chantable tubers, and this has been true even in years in which 

 there was no appreciable blight present. If the per cent and a 

 half more of starch found in the sprayed than in the unsprayed 

 tubers is due to the treatment of the vines, and no other explan- 

 ation suggests itself, this is an added argument in favor of 

 spraying with Bordeaux mixture. 



COMPOSITION AS AFFECTED BY COOKING 



From potatoes being used in a feeding experiment two lots 

 of 1000 grams each were selected. One lot was prepared at 

 once for analysis and one lot was steamed until cooked before 

 being prepared. The cooked lot weighed 1022 grams when re- 

 moved from the steamer, but when cooled in the open air this 

 added water evaporated and they weighed 995 grams or 5 

 grams less than before being steamed. The raw potatoes car- 

 ried 24.1 per cent of dry matter and the cooked 24.63 per cent. 

 The 1000 grains of raw potatoes therefore carried 241 grams 

 ■of dry matter and the 995 grams of steamed potatoes 245 grams. 

 As will be noted the differences are all slight and within lab- 

 oratory error. The composition on dry basis follows : 



Table Showing the Analyses of Raw and Steamed Potatoes 



From the Same Lot, Calculated to Waterfrce Basis 



(Dry Matter) 





Protein 



Fiber 



Nitrogen- 

 tree extract* 



Fat 



Asb 





% 



% 



% 



% 



% 



Raw 



10.91 



2.30 



82.85 



.54 



3.40 



Steamed 



10.70 



2.78 



82.67 



.28 



3.57 



•Nitrogen-free extract includes all of the carbohydrates other than fiber. 



