MINERAL FOOD OF PLANTS. 119 
small quantities from the soil, which form a part 
of the necessary food of the tree. 
It will perhaps be interesting to give one more 
illustration of the proofs of the truth before we 
part with it; which we shall do in the following 
manner. A few years ago, after a terrible thun- 
der storm, in Germany, some persons in passing 
through a meadow came to a heap of black 
shining glassy substance, which they were much 
perplexed about. This mass was taken to the 
learned men of the town, and caused to them 
as much perplexity as it had done to the rusties 
who brought it to them. Some said it was this 
thing; others said it was that; and the great 
number of them believed it to be a stone fallen 
from the sky, of the same nature as those called 
meteoric stones, which we well know to have 
done so. After some time it was determined to 
get a chemist to unravel the difficulty; and a 
piece of the substance was given to him to try 
his experiments on, in the hope that he might be 
able to tell what it was. In the meanwhile the 
owner of the meadow was astonished to find that 
a good-sized stack of hay, which he had carefully 
placed in this very meadow, was gone, nowhere 
