THE ASH OF PLANTS. 165 



gredients, viz. chlorine and sulphuric acid, should he re- 

 duced to uniformity, and the analyses then be recalculated 

 to per cent. 



In the first place, however, we are not warranted in 

 assuming that the " excess " of chloride of potassium, car- 

 bonate of potash, etc., deducted in the above analyses 

 respectively, was all accidental and unnecessary to the 

 plant, for, under the influence of an increased amount of a 

 nutritive ingredient, the plant may not only mechanically 

 contain more, but may chemically employ more in the 

 vegetative processes. It is well proved that vegetation 

 grown under the influence of large supplies of nitrogenous 

 manures, contains an increased proportion of nitrogen in 

 the truly assimilated state of albumin, gluten, etc. The 

 same may be equally true of the various ash-ingredients. 



Again, in the second place, we cannot say that in any 

 instance the minlmmn quantity of any ingredient neces- 

 sary to the vegetative act is present, and no more. 



It must be remarked that these great variations are only 

 seen when we compare together plants produced onpoor 

 soils, i. e. on those which are relatively deficient in some 

 one or several ingredients. If a fertile soil had been cm- 

 ployed to support the buckwheat plants in these trials, we 

 should doubtless have had a very difierent result. 



In 1859, Metzdorf, ( Wilda's CentralUatt, 1862, 2, p. 

 367,) analysed the ashes of eight samples of the red-onion 

 potato, grown on the same field in Silesia, but difierently 

 manured. 



Without copying the analyses, we may state some of 

 the most striking results. The extreme range of variation 

 in potash was 5^- per cent. The ash containing the high- 

 est percentage of potash was not, however, obtained from 

 potatoes that had been manured with 50 pounds of this 

 substance, but from a parcel to which had been applied a 

 poudrette containing less than 3 pounds of potash for the 

 quantity used. 



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