Analyses of Ashes of Plants. 183 



This table affords a most singular instance of the distribution of 

 the ash : the mineral matter of Specimen 84 seems to have changed 

 places with that of 86 — in the one case its largest amount being 

 in the bulb, in the other in the leaf. It seems truly extraordinary 

 that with such deviating per centages of ash, the final result 

 should be so nearly alike. This is, however, due to the differ- 

 ence not only in the per centage of ash in the bulb and leaf, but 

 also to the proportion between the bulb and top. Were we to 

 make the calculation upon the supposition that the top is the 

 same in all cases, the result would be very different. Let us 

 take the average of 90 of bulb to 10 of top. The results would 

 then be as follows ; — • 





Mineral Matter in a Ton 



Speci- 



of entire Crops. 



mens. 











Bulb. 



Top. 



Both. 



84 



20-4 



2-7 



23-1 



85 



14»6 



5-0 



19-6 



86 



12-1 



4«1 



16-2 



Here all similarity in the final result vanishes, without any uni- 

 formity in the mineral matter of the several parts being obtained. 

 The proportion of bulb to top is then one element of the calcu- 

 lation not to be neglected, and the results above given go far to 

 prove the accuracy of our estimations of these quantities. The 

 practical deduction from these facts is highly important. The 

 bulbs or tops of any particular crop may contain a very varying 

 proportion of mineral matter — influenced, in all probability, by 

 its age and other circumstances which have yet to be ascertained ; 

 but a given weight of the whole crop will never very greatly vary 

 in its mineral constitution. Any calculations founded upon the con- 

 stitution of either the bulb or top separately must be taken with 

 very great limitations ; suppose, for instance, the tops of the turnips 

 to be left in all cases on the land, but that half of the bulbs (say 

 10 tons, the whole crop of bulbs being 20 tons) are drawn for 

 consumption by cattle in the yards, the quantity of mineral matter 

 removed from the soil might in one instance be 1 1 2 lbs. (Speci- 

 men 86), or in another case 213 lbs. (Specimen 84), whereas in a 

 given weight of the whole produce, the mineral matters would be 

 very nearly alike — (202 and 218 lbs.). We have said that this is of 

 practical importance : we should rather say that it is of great im- 

 portance in all practical experiments which are undertaken for the 

 sake of establishing the rationale of the growth of crops. If it be 

 sought to establish the relative effect of different manures on the 

 crops following that one for which they are applied, it will not 

 do to remove from each piece of land under trial a similar quan- 



