BULLETIN OF THE BUSSEY INSTITUTION. 15 
by analysis with regard to the comparative fertility, or rather sterility, 
of these sands generally agree very closely with those which have 
been obtained by the method of cultivating plants in the sands. 
Indeed I am inclined to believe that the fact is a general one, and 
that it will probably be found to be true, or very nearly true, of most 
sands and of soils that are equally sterile with the sands, excepting 
always clays and exceedingly fine rock-dust, which cannot easily be 
tested by the method of plant culture, since the fine adhesive particles 
of clay, or the like, clog the root-pores and present very serious 
mechanical obstacles to the growth of plants. In other words, contrary 
to what is now commonly believed to be true of most cultivable soils, 
it appears that the chemical analysis of exceedingly poor soils, devoid 
of organic matter, is competent to detect their peculiarities and to 
afford a tolerably correct idea of the comparative capabilities of such 
soils to support plants. 
At first sight it may seem somewhat surprising that the sands 
should contain such comparatively large proportions as they do of 
potash and phosphoric acid. But the fact that sands are seldom 
free from these constituents has long been known and has been often 
insisted upon. ‘Those chemists in particular who have occupied them- 
selves with experiments by way of sand-culture have frequently 
lamented the practical impossibility of obtaining sand absolutely free 
from matters such as potash, phosphoric acid, and the other essential 
elements of the food of plants. Wiegmann and Polstorff* in their 
experiments of 1842, dwell upon this difficulty, and Hellriegel,t the 
most successful of all the experimenters upon sand-culture, was forced 
to content himself with sand that was not absolutely free from such 
contamination. 
Professor Senft, has well said}: “ In ordinary life we often conceive 
of sand as if it were an aggregation consisting of nothing but grains of 
quartz. But the idea is a false one; and, because of its falsity, it has 
given rise to many erroneous conclusions, both as to the comparative 
fertility of the so-called sand-soils; with regard to what is required by 
different kinds of plants from the soils that support them; and, in 
general, as to what constitutes the necessary food of plants.” . . 
* “Flora,” 1843, 26. 27. 
+ Hoffmann’s “Jahresbericht der Agrikultur-Chemie,” 1861-2, 4. pp, 112, 118. 
t In his “‘ Steinschutt und Erdboden,” Berlin, 1867, page 195. 
