168 



Analyses of Ashes of Plants. 



We will now endeavour to deduce some general principles 

 from the analyses which have been detailed. 



It should be clearly understood, however, that any views that 

 may be advanced, cannot take from the reliance to be placed 

 upon the analyses themselves. We may be right or wrong in the 

 conclusions to which we are led by a review of the data before 

 us ; but be this as it may, the results obtained must be looked 

 upon as matter of fact, and they are given in the fullest detail, so 

 as to afford to every member of the Society the materials for form- 

 ing his own judgment on the question. And first, let us examine 

 the evidence concerning turnips. 



In the last paper on wheat, we endeavoured to show that a 

 consideration of the quantity of mineral matter removed by any 

 crop, must necessarily include the relation in quantity existing 

 between the different parts of the plant under examination. Were 

 the ash of every portion of a plant the same in quantity and com- 

 position, a knowledge of the gross produce in any given case 

 would suffice to indicate the amount of exhaustion produced. This 

 is any thing but the actual state of things. The parts of plants 

 differ in mineral composition fully as much as one entire plant 

 does from another. To establish the relation between the grain 

 and straw of a cereal was not a dlfhcult matter, and reasons were 

 given for believing that we had arrived at more accurate results 

 than could be obtained on the large scale. 



In separating the grain from the straw of 50 or 60 heads of 

 wheat, there is every reason to believe that a correct average of 

 the whole crop may be obtained ; the number of individual 

 plants being sufficient to destroy the effect of any one or two 

 which might differ from the rest. But in the separation of the 

 bulb of the turnip from the top, it is extremely difficult to say 

 where the one begins and the other ends, and a very little devia- 

 tion in this respect will undoubtedly influence the result of the 

 estimation. It is probable that, to ensure the nearest approach 

 to correctness, a very great number of turnips must be operated 

 upon ; but as such an estimation was not within our reach, we 

 have adopted the best method under the circumstances, and trust 

 that the numbers obtained may not be far from the truth. 



The specimens of turnips were, as before mentioned, obtained 

 from different localities, and many of them from great distances. 

 They were always perfect specimens,* that is, the leaves were 



* The accompanying printed directions which were forwarded to all 

 parties who supplied us with crops, will at once show the precautions 

 which were adopted to secure perfect specimens. 



Should any member of the Society be desirous of aiding the present in- 

 vestigation, by contribution of specimens for analysis, a copy of the paper 

 of questions which is employed by us to obtain information concerning 



