PHYSICAL PROPERTIES OF SOILS. 63 
sugar production can only thus be determined. So, too, 
the specific influence of any fertilizing agent upon the 
growth or nutrition of the cane, may be regarded as accu- 
rately fixed only under certain conditions. 
The texture and other physical properties of soils have 
generally a no less important influence upon their fertility 
than those that are strictly chemical. The former being 
readily perceptible are well known, and may be pretty 
clearly defined; and as they are dependent upon, and, to a 
certain degree, indicate the chemical composition, they 
mark the most characteristic points of ‘distinction between 
different soils. 
Correspondent to the quality of the soil, the juice of the 
cane has been found to undergo, uniformly, various degrees 
of modification, and although much is yet to be learned on 
this head experimentally, enough is known to enable us to 
indicate certain soils as peculiarly favorable to the pro- 
duction of the saccharine matter in the juice of sorghum, 
almost free from impurities which hinder crystallization, 
while others are in an equal degree unfavorable in this re- 
spect. This difference in lands not artificially manured, ap- 
pears the most broadly marked when we compare a light, 
friable limestone soil with a wet alluvial one, or one but re- 
cently cleared, and composed in great part of humus or decay- 
ing vegetable matter. Upon the last-mentioned variety of 
soil sorghum grows rank and tall, but its period of growth 
is inordinately lengthened, the seed fails to mature early, 
the juices are diluted and mucilaginous, the crystallization 
of the sugar is accomplished with greater difficulty, and 
the yield either in sugar or refined syrup is less even than 
that usually obtained from half worn-out upland soils. 
The worst possible condition of the juice is attained when 
the humus is replaced or reinforced by barn-yard or other 
stimulating ammoniacal manures in large quantity ; in such 
