COMPOSITIOIf IN SUCCESSIVE STAGES. 217 



The gain during each period was accordingly as fol- 

 lows : 



100 " 100 " 100 " 100 " 100 " 



6. — As regards the individual ingredients of the ash, 

 the plant contained at the end of each period the follow- 

 ing amounts, — the total quantity in the ripe plant being 

 taken at 100. Corresponding results from Bretschneider 

 enclosed in ( ) are given for comparison. 



The gain (or loss, indicated by the minus sign — ) in 

 these ash-ingredients during each period is given below. 



Silica. '^"Sf"' ^""am"" -^'"»«- ^raanesia. Potash. 



Per cent. Per cent. Per cent. Per cent. Per cent. Per cent. 



I. Period, 18 ( 22) 20 ( 42 ) 23 ( 23) SO ( 31 ) 24 ( 31) 89 ( 43 ) 



m. " 1^33) S2|( 2) ll](iO) |8}(S2) \l\(.iV |;|C47) 



IV. " 23 ( IS) 33 f— 5») 18 ( 10) 20 (— 9«) 26 ( 4 ) 9 ( 11 ) 



V. " 7 ( 28) 10 ( 56 ) 9 ( 27) 1 ( 17 ) 16 ( 23) (—5*) 



100 (100) 100 (lOOJ 100 (100) 100 (100) 100 (100) ioT (100) 



These two independent investigations could hardly give 

 all the discordant results observed on comparing the above 

 figures, as the simple consequence of the unlike mode of 

 conducting them. We observe, for example, that in the 

 last period Arendt's plants gathered less silica than in any 

 other — only "^"l „ of the whole. On the other hand, Bret- 

 schneider's croiD gained more silica in this than in any 



* In these instances Bretsclineider's latercrops contained less sulpliurlc acid, lime, 

 and potash, than the earlier. This result may be due to the -washing of the crop by 

 fftins, but is probably caused by unequal development of the several plots. 



10 



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