44 ANALYSES OF THE POTATO. 



Another specimen of the rose end gave. 



Water 74-04 



Ash 0-94 



As tliis variety is one of the best for illustrating the difference in composition of the dif- 

 ferent parts, I have divided it into three portions, viz. rose end, heel end, and middle. 

 These divisions, however, are not exact by measure ; three parts, nearly equal lengths, 

 only being taken, without regard to exact lines of demarkation denoted by the position 

 of the eyes. 



It is evident from an inspection of the results of the analyses, that the ends differ from 

 each other, and also from the middle. I had, however, too little ash in each instance, 

 and not as much as is required for the most trustworthy analysis ; still, on comparing them 

 with the results of others, I find there is a sufficient coincidence to bear out the expecta- 

 tion that they approximate very closely to their true composition. I fear, however, that 

 there is too great a difference between the middle and ends, or it may be that it is greater 

 than will lie found by subsequent trials; yet there is clearly a foundation for suspecting 

 that there are real and permanent differences in their composition. The amount of water 

 in the ends, and of solid matter, anil the proportion of ash, are considerations which lead 

 to the conclusion that these differences are not due to errors of analysis. The most re- 

 markable differences are found in the amount of potash and of the phosphates. 



It may be interesting to copy two analyses of P. F. H. Frombeug, assistant in the 

 Laboratory of the Agricultural Chemistry Association of Scotland : 



Rose end. Heel end. 



Potash 38-15 29-53 



Soda 5-40 11-26 



Chloride of sodium .... 6-25 9-66 



Lime 1-2S 1-55 



Magnesia 5 90 3 96 



Oxide of iron 103 1-34 



Sulphuric acid 24-32 20-63 



Phosphoric arid 12-81 20-73 



Silica 4-86 1-34 



100-000 100 000 



In order to compare these analyses with my own, it is necessary to state that the lime 

 and magnesia here given is in combination with phosphoric acid ; and that in my own, 

 those bodies are merged in the general composition of the phosphates. 



