=226. Tobacco Stems and Waste.=—Until within a few years tobacco stems
and other waste from factories, were treated as a nuisance in this
country, and burned or dumped into streams. By burning and saving the
ash the potash contained in the stems and waste would be recovered in a
form suitable for field use. The nitrogen, however, contained in these
waste materials, both in the form of nicotin and of albuminoids would
be lost. Ignition of this waste, therefore, should not be practiced. It
should be prepared for use by grinding to a fine powder. Applied to the
soil in this condition the powder may be useful as an insecticide as
well as a fertilizer. Tobacco stems contain from twelve to twenty-seven
per cent of moisture, and from twelve to twenty per cent of ash. The
composition of the stems from two celebrated tobacco growing regions is
subjoined:[185]
Kentucky stems. Connecticut stems.
Moisture 26.70 per cent. 13.47 per cent.
Organic and volatile 60.18 “ “ 70.85 “ “
Ash 13.12 “ “ 15.68 “ “
The ash calculated to the original substance had the following
composition:
Kentucky stems. Connecticut stems.
Phosphoric acid 0.67 per cent. 0.53 per cent.
Potash 8.03 “ “ 6.41 “ “
It is thus seen that about half the ash of tobacco stems is composed
of potash. The stalks of the tobacco have almost the same composition
as the stems, but the percentage of ash is not quite so great. In
three samples analyzed at the Connecticut station the percentages
of ash found in the water-free substance were 6.64, 7.00, and 7.46
respectively. The pure ash of the stalks was found to have the
following composition:[186]
Description of samples.
Constituents Cut Aug. 22. Cut Sept. 17.
Silica 0.82 per cent. 0.57 per cent.
Iron and aluminum oxids 1.38 “ “ 1.38 “ “
Lime 14.01 “ “ 16.58 “ “
Magnesia 6.64 “ “ 7.36 “ “
Potash 56.34 “ “ 54.46 “ “
Soda 1.28 “ “ 1.16 “ “
Sulfuric acid 8.06 “ “ 6.75 “ “
Phosphoric acid 6.37 “ “ 6.27 “ “
Chlorin 6.55 “ “ 7.05 “ “
------ ------
101.45 “ “ 101.58 “ “
Deduct oxygen = chlorin 1.45 “ “ 1.58 “ “
------ ------
100.00 “ “ 100.00 “ “
The leaves of the tobacco contain more ash than the stalks or stems,
but the percentage of potash therein is less. In eighteen samples
analyzed at the Colorado station the percentages of moisture in
the leaf varied from 6.08 to 28.00, and those of ash from 22.60 to
28.00.[187] The percentages of potash in the ash varied from 15.20 to
26.30. In these data the carbon dioxid, sand, etc., are included, while
in those quoted from the Connecticut station they were excluded.
=227. Cottonseed Hulls and Meal.=—A considerable quantity of potash is
added to the soil in cottonseed meal and hulls. The practice of burning
the hulls cannot be recommended, although it is frequently practiced,
for the incineration does not increase the quantities of phosphoric
acid and potash, while it destroys the availability of the nitrogen.
Nevertheless the analyst will often have to deal with samples of the
raw materials above mentioned, as well as with the ash of the hulls, in
which the potash can be determined by some one of the standard methods
to be described. In general it is found that the hulls of seeds and the
bark and leaves of plants have a greater percentage of ash than the
interior portions. In the case of cottonseed however, an exception is
to be noted. The cottonseed meal in the air-dried state has about seven
per cent of ash, while the hulls have only about three. When it is
remembered, however, that the greater part of the oil has been removed
from the meal it will be seen that in the whole seed in the fresh state
the discrepancy is not so marked.
In the crude ash of the hulls the percentage of potash varies generally
from twenty to twenty-five per cent, but in numerous cases these
limits are exceeded. In twelve samples of cottonseed hull ashes
examined by the Connecticut station the mean percentage of potash in
the crude sample was 22.47, and the extremes 15.57 and 30.24 per cent
respectively.[188] In determining the value of the ash per ton the
content of phosphoric acid must also be taken into account.
Cottonseed meal contains about 1.75 per cent of potash. Since the mean
percentage of ash in the meal is seven, the mean content of potash in
the crude ash is about twenty-five.
=228. Wood Ashes.=—Unleached wood ashes furnish an important quantity
of potash fertilizer. The composition of the ash of woods is extremely
variable. Not only do different varieties of trees have varying
quantities of ash, but in the same variety the bark and twigs will give
an ash quite different in quantity and composition from that furnished
by the wood itself. In general the hard woods, such as hickory, oak,
and maple, furnish a quality of ash superior for fertilizing purposes
to that afforded by the soft woods, such as the pine and tulip trees.
The character of the unleached wood ashes found in the trade is
indicated by the subjoined analyses. The first table contains the mean,
maximum and minimum results of the analyses of ninety-seven samples by
Goessmann.[189]
Mean composition of wood ashes.
Means. Maxima. Minima.
Potash 5.5 10.2 2.5
Phosphoric acid 1.9 4.0 0.3
Lime 34.3 50.9 18.0
Magnesia 3.5 7.5 2.3
Insoluble 12.9 27.9 2.1
Moisture 12.0 28.6 0.7
Carbon dioxid and undetermined 29.9
In sixteen analyses made at the Connecticut station the data obtained
are given below:[190]
Means. Maxima. Minima.
Potash 5.3 7.7 4.0
Phosphoric acid 1.4 1.8 0.9
In fifteen analyses of ashes from domestic wood-fires in New England
stoves, the following mean percentages of potash and phosphoric acid
were found:
Potash 9.63
Phosphoric acid 2.32
In leaching, ashes lose chiefly the potassium carbonate and phosphate
which they contain. Leached and unleached Canada ashes have the
following composition:
Unleached. Leached.
Insoluble 13.0 per cent. 13.0 per cent.
Moisture 12.0 “ “ 30.0 “ “
Calcium carbonate and hydroxid 61.0 “ “ 51.0 “ “
Potassium carbonate 5.5 “ “ 1.1 “ “
Phosphoric acid 1.9 “ “ 1.4 “ “
Undetermined 6.6 “ “ 3.5 “ “
In the wood ashes of commerce therefore, it is evident that the
proportion of the potash to the lime is relatively low.
The number of parts by weight of the chief ingredients of the ash in
ten thousand pounds of woods of different kinds is given in the table
below together with the percentage composition of the pure ash, that is
the crude ash deprived of carbon and carbon dioxid.