134 QUARTERLY JOURNAL. 



about 5i lbs. consist of principles of prime value to all species of 

 crops.* 



4:ih. Sweet Potatoe, {Yam.) 



The tubers analysed, though fresh from the market, were obvi- 

 ously drier than when first harvested. 



One hundred parts of the thinly sliced tubers on being tho- 

 roughly dried at a temperature of 200°, lost 58.97 per cent of 

 water. 



One hundred parts of the undried potatoe gave 1.09 parts, or 

 rather over 1 per cent of a white ash stained in points of a bluish 

 green color. 



Its composition was as follows : — 



Carbonate of potassa, (with traces of soda) 60.00 



Phosphate of lime, 14 .57 



Phosphate of magnesia, 5 . 60 



Carbonate of lime, , 5 ..39 



Carbonate of magnesia, 3 . 80 



Chloride of potassium, 4 , 60 



Sulphate of potassa, 4 . 35 



Silica, 70 



Chloride of calcium, "] 



Sulphate of magnesia and lime, ! , , qq 



AT* f clllU loss. •••••• . •J'J 



Alumma, , ( ' 



Oxide of iron and manganese in traces, J 



100.00 



One hundred parts of the ash from the sweet potatoe tuber, con- 

 tains then the following inorganic principles which must have been 

 withdrawn from the soil. 



Potassa, 43 .59 



Phosphoric acid, 11 .08 



Lime, 10.12 



Magnesia, 3 . 80 



Potassium, 2 .42 



Chlorine, 2.18 



Sulphuric acid, 1 . 90 



85.09 



* In n recent number of the Boston Journal of Natural History, I observe some ob- 

 servations by Dr. Cliarlos T. .Tackson, on the inorg:anie constitution of Indian corn, 

 wlierein Dr. J. supjjoses phosjihoric acitl to be jirescnt in Ihe grain, in a free or un- 

 conibined state. The experiment wiiich led him to form this conjecture, did by r > 

 means succeed in my hands as describetl by him ; for althousrh the grain was repo, - 

 edly incinerated upon a bright planMna foil under a miifller, stiU tlic metal lost imne 

 of its polish or malleability. Neither can I agree with Dr. J. in his opinion of the 

 presence of ammonia as a base in Indian corn; the volatile alkali obtained by him, 

 being a product rather than an educl of the analysis. 



