272 
Journal of Agricultural Research , 
Vol. VII ? No. 6 
METHOD OF SEPARATION OF GRAIN FROM THE DEAF AND MECHANICAL 
ANALYSIS OF THE LEAF 
Preliminary investigations indicated that a considerable supply of the 
grain bodies free from the surrounding tissues of the leaf would be de¬ 
sirable. A method of mechanical separation was therefore worked out, 
which, in brief, is as follows: A quantity of air-dry cigar leaf tobacco was 
rubbed through a series of sieves (from io to 150 mesh) with a flat pestle 
made from a rubber stopper. This process removed a large amount of 
the soft web of the leaf from the veins as well as from the hard grain 
particles, at the same time breaking the veins into short lengths, but 
not crushing the grain. The mixture of grain and vein remaining in 
each sieve was then ground in an unglazed porcelain mortar with a 
rounded rubber pestle. This served to remove any soft tissue still 
adhering to the particles of grain and vein. After sifting out with the 
appropriate sieve the small amount of fine material thus rubbed off, the 
mixture of grain and vein remaining was slowly poured upon a piece of 
smooth paper inclined at an appropriate angle, determined by experiment. 
The more or less spherical particles of grain rolled down the inclined paper 
more rapidly than the cylindrically-shaped pieces of vein, resulting in 
a partial separation of the former from the latter. It was found, however, 
that a large amount of the grain belonging to the flatter types remained 
with the vein, and it was therefore necessary to pick this grain out of the 
mixture with the aid of a binocular microscope. By these tedious means 
about 30 or 40 gm. of practically pure grain were obtained for subse¬ 
quent detailed study. 
The separation of the grain and vein from the soft tissues of the leaf in 
this manner in one instance also resulted in an approximate mechanical 
analysis of the tobacco leaf. It was found that of a 70-gm. sample the 
midribs represented about 33 per cent of the weight, while the soft tissue 
(that which passed through a 150-mesh sieve) constituted 48 per cent; the 
veins (other than the ribs), 8 per cent; and the grain, n per cent. Ex¬ 
cluding the ribs, the soft tissue represented 70 per cent; the veins, 12 per 
cent; and the grain, 17 per cent by weight. These results are only approxi¬ 
mate, since the primary object of the separation was to obtain a quantity 
of the pure grain, and the determination of the proportion of various 
tissues was an afterthought. It seems probable, however, that an im¬ 
proved method for the accurate mechanical analyses of tobacco would be 
highly desirable, inasmuch as its various properties doubtless depend in 
a large part upon the proportion of these three components of the leaf— 
namely, soft tissue, vein, and grain. 
CHEMICAL NATURE OF GRAIN 
Chemically, the grain has been supposed by Sturgis (7) and by Loew 
(5, p. 38-39) to be calcium oxalate, while from the fact that the grain 
particles produce minute explosions as fire reaches them in the process of 
