THE INOBGANIC ELEMENTS OF PLANTS. 



PART SECOND. 



CHAPTER XV. 



THE INORGANIC ELEMENTS OF PLANTS. 



When any vegetable substances are burned in the air, 

 the whole of the organic elements disappear, and a small 

 quantity of ash remains. The proportion of the substance 

 which has disappeared varies from 88 to 99 per cent. This 

 has all been derived from the air, and is made up of the 

 four elements which have occupied our attention up to this 

 point. The small remnant left after complete combustion 

 constitutes the inorganic elements of plant growth. These 

 are now to be studied. 



The results of recent investigations have wholly exploded 

 the notions which formerly prevailed, to the effect that this 

 inorganic matter was of no serious importance to the crops, 

 and was a mere accidental circumstance, and might be ab- 

 sent without any serious detriment to the growth of the 

 plants. It was discovered in course of careful experiments 

 that this ash of the plants represented exactly the various 

 mineral substances which were taken from the soil, and that 

 these, to the smallest proportion, were of vital necessity to 

 the plants. 



The results of long continued study, finally gathered into 

 systematic order, showed that on whatever soil a plant might 

 be grown and mature its seed fully, the quantity and char- 

 acter of the ash is nearly the same ; and that though grown 

 on the same soil, plants of different species and character 

 leave an ash entirely unlike; the ash varying characteristic 



