PHOSPHOKIC ACID AND POTASH IN GROWING TURNIPS. 21 



These figures show that tlie quantity of phosphoric acid 

 taken up daily by the turnip plants growing on one acre 

 of ground increases from the commencement of the 

 second to the end of the fourth stage of growth, that is 

 in ninety days from 0*924 to 1*25 pound a-day, which 

 reckoned fi'om one day to another makes the trifling 

 difference of 0-0037 pound a-day. 



Anderson suspects that his estimate of the nitrogen in 

 the leaves during the third stage was not quite correct, 

 and that it fell below the actual amount. If we add 

 together the quantities of nitrogen absorbed in the last 

 two stages, fifty-five days, we find a daily average of 1-02 

 pound of nitrogen, which is very nearly the same as in 

 the preceding stage of growth. 



The quantity of potash increased from the 11th August 

 till the 1st September, in a somewhat higher ratio than 

 the amount of vegetable substance produced. From the 

 1st September till the 5th October the increase of the 

 roots was nearly double what it had been in the preceding 

 stage, but this is explained by the migration of the potash 

 compounds from the leaves to the roots. It is evident 

 that the increase of potash has a certain connection with 

 the formation of sugar and the other non-nitrogenous 

 constituents of the roots, but no definite proportion can 

 be established between them. The absorption of sul- 

 phuric acid increased uniformly in the three last stages ; 

 that of salt was a httle greater in the third than in the 

 second and fourth stages. 



Without Avishing to indicate the exact part performed 

 in the process of vegetation by these various mineral 

 substances, as also by lime, magnesia, and iron, we remark 

 that, except in the case of potash, the absorption of them 

 was evidently uniform from day to day, yet showing every 

 day a trifling increase corresponding to the daily increase 



