80 THE JERUSALEM ARTICHOKE CROP. 



return of 640 frs. From this M. Doniol deducts the out- 

 goings for rent, taxes, labour, &c., which amounted to 

 28075 frs., the balance, 359-25 frs., being the net profit on 

 the half-hectare = 11, 10s. per acre. In all cases the 

 tubers left in the ground were more than sufficient to 

 secure a full plant for the succeeding year's crop. These 

 surely are encouraging returns for soils such as M. 

 Doniol describes his to be, and would show that we are 

 negligent of our own interests in treating the plant with 

 so little attention as we have hitherto done. There must 

 be many persons having suitable pieces of ground in their 

 occupation, frequently lying as waste places, or only occa- 

 sionally tilled, which under cultivation with this crop 

 would produce very remunerative returns. 



The diseases to which the plant is subject cannot be of 

 much importance, as no mention is made of them by the 

 several authorities who have written about its cultivation. 

 Its chemistry, however, has received some little attention ; 

 from which we find that the ash or mineral matter con- 

 tained in the tuber amounts to T79 per cent., in the stem 

 l*94i per cent., and in the leaves 15* per cent. 



The composition of the mineral matter of the root has 

 been investigated by Boussingault, who gives it as 

 follows : 



Potash, 54-67 



Soda, traces 



Lime, 2'82 



Magnesia, 2'21 



Iron and Alumina, 6*39 



Phosphoric acid, 13'27 



Sulphuric acid, 2 70 



Silica, 15-97 



98-03 



Messrs. Way and Ogston included the Jerusalem arti- 

 choke in their analyses of the ashes of farm plants, and 

 found that a ton of tubers removed from the soil the fol- 

 lowing quantities of mineral substances: 



