180 QUALITY OF THE ASH FROM DIFFERENT PLANTS. 



tal fact, that if a healthy young plant be placed in circumstances where 

 it cannot obtain this inorganic matter, it droops, pines, and dies. 



2°. But if it be really essential to their growth, this inorganic matter 

 must he considered as part of the food of plants ; and we may as cor- 

 rectly speak of feeding or supplying food to plants, when we add earthy 

 and mineral substances to the soil, as when we mix with it a supply of 

 rich compost, or of well fermented farm-yard manure. 



I introduce this observation for the purpose of correcting an erroneous 

 impression entertained by many practical men in regard to the way in 

 which mineral substances act when applied to the soil. By the term 

 manure they generally designate such substances as they believe to be 

 capable o^ feeding tfie plant, and hence reject minerat substances, such 

 as gypsum, nitrate of soda, and generally lime, from the list of manures 

 properly so called. And as the influence of these substances on vegeta- 

 tion is undisputed, they are not unfrequently considered as stimulants only. 



Yet if, as I believe, the use of a wrong term is often connected 

 with the prevalence of a wrong opinion, and may lead to grave errors 

 in practice, — I may be permitted to press upon your consideration 

 the fact above stated — I may ahnost say demonstrated — that plants 

 do feed upon dead unorganized mineral matter, and that you are, there- 

 fore, really manuring your soil, and permanently improving it, when 

 you add to it such substances of a proper kind. 



§ 2. Of the kind of inorganic matter found in plants. 



I have said above, of a proper kind — for it is not a matter of indiffer- 

 ence to a plant, what kind of earthy or saline matter it takes in by its 

 roots. Each species of plant, we have seen, withdraws from the soil a 

 quantity of inorganic matter, whi(j^ is peculiar to itself, and which, as a 

 whole, is nearly constant. 



So also each species, in selecting for itself a nearly constant weight 

 of inorganic matter, while it chooses generally the same kind of saline 

 and earthy ingredients as other plants do, to make up this weight, yet 

 picks them out in proportions peculiar to itself Thus for example, lime 

 is present in the ash of nearly all plants, but while 100 lbs. of the ash 

 of wheat contain 8 pounds of Hrae, the same weight of the ash of barley 

 contains only 4i lbs. So also potash is contained iu the ash of most 

 plants grown for food, but in the ash of the turnip, there are 37i per 

 cent, of potash, while in that of wheat there are only 19 per cent. Again, 

 in different parts of the same plant, a like difference prevails. The ash 

 of the turnip bulb contains 16i per cent, of soda, — that of the leaf, Httle 

 more than 12 per cent. On the other hand, the lime in that from the 

 bulb constitutes less than 12 per <:ent. of its weigb% while in that of the 

 leaf it amounts to upwards of 34 per cent. 



These relative proportions among the different kiuds of inorganic mat- 

 ter contained in the ash of plants — like the whole weight itself of the 

 ash — is nearly constant in the same species, and in the same part of a 

 plant, when it is grown in a propitious soil. It is not, therefore, as I have 

 already said, a matter of indiilerence to the living vegetable, whether 

 it meets with this or with that kind of inorganic matter in the land on 

 which it grows — whether its roofs are supplied with lime, or with potash, 

 cr ^ith soda. The soil must contain all these substances^ and in such 



