ORGANIC SOURCES OF POTASH.
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.
Pounds of the Ingredients Named
in Ten Thousand Pounds of Wood.
| Dogwood. | Sycamore. | Post oak. | Ash. | Red Oak. | Hickory. | |
|---|---|---|---|---|---|---|
| Cornus florida. | Platanus occidentalis. | Q. obtusiloba. | F. Americana. | Q. rubra. | Carya tomentosa. | |
| Potash | 9.02 | 18.06 | 16.85 | 14.94 | 13.95 | 13.80 |
| Phosphoric acid | 5.72 | 9.55 | 6.96 | 1.15 | 5.98 | 5.83 |
| Lime | 6.41 | 24.73 | 35.61 | 7.60 | 27.40 | 18.40 |
| Magnesia | 14.67 | .49 | 5.28 | .10 | 3.05 | 4.86 |
| White oak. | Magnolia. | Georgia pine. | Yellow pine. | Black pine. | Chestnut. | Old field pine. | |
|---|---|---|---|---|---|---|---|
| Q. alba. | M. grandiflora. | P. palustris. | P. mitis. | Picea nigra. | Castanea vesca or sativa. | P. mitis. | |
| Potash | 10.60 | 7.13 | 5.01 | 4.54 | 3.02 | 2.90 | .79 |
| Phosphoric acid | 2.49 | 3.19 | 1.24 | .96 | .92 | 1.09 | .73 |
| Lime | 7.85 | 14.21 | 18.04 | 15.16 | 12.46 | 7.93 | 12.12 |
| Magnesia | .90 | 2.94 | 2.03 | .74 | .10 | .34 | 1.17 |
The Pure Ashes of the Woods
Contain the Following Per Cents
of the Ingredient Named.
| Dogwood. | Sycamore. | Post oak. | Ash. | Red Oak. | Hickory. | |
|---|---|---|---|---|---|---|
| Cornus florida. | Platanus occidentalis. | Q. obtusiloba. | F. Americana. | Q. rubra. | Carya tomentosa. | |
| Potash | 28.04 | 23.17 | 21.92 | 46.04 | 24.66 | 28.60 |
| Phosphoric acid | 8.51 | 12.23 | 9.00 | 3.58 | 10.55 | 11.97 |
| Lime | 38.93 | 31.62 | 46.39 | 23.57 | 48.26 | 37.94 |
| Magnesia | 6.80 | .62 | 6.88 | .60 | 5.38 | 10.04 |
| White oak. | Magnolia. | Georgia pine. | Yellow pine. | Black pine. | Chestnut. | Old field pine. | |
|---|---|---|---|---|---|---|---|
| Q. alba. | M. grandiflora. | P. palustris. | P. mitis. | Picea nigra. | Castanea vesca or sativa. | P. mitis. | |
| Potash | 42.16 | 19.54 | 15.35 | 19.70 | 14.30 | 18.10 | 3.85 |
| Phosphoric acid | 9.48 | 8.75 | 3.82 | 4.18 | 4.33 | 6.76 | 4.11 |
| Lime | 29.85 | 38.94 | 55.24 | 65.53 | 58.98 | 49.18 | 67.73 |
| Magnesia | 3.43 | 8.05 | 6.25 | 3.20 | .50 | 2.11 | 6.54 |
229. Fertilizing Value of Ashes.—Primarily, the fertilizing value of wood-ashes depends on the quantity of plant food which they contain. With the exception of potash and phosphoric acid, however, the constituents of wood-ashes have little, if any, commercial value. The beneficial effects following the application of ashes, however, are greater than would be produced by the same quantities of matter added in a purely manurial state. The organic origin of these materials in the ash has caused them to be presented to the plant in a form peculiarly suited for absorption. Land treated generally with wood-ashes becomes more amenable to culture, is readily kept in good tilth, and thus retains moisture in dry seasons and permits of easy drainage in wet. These effects are probably due to the lime content of the ash, a property moreover favorable to nitrification and adapted to correcting acidity. Injurious iron salts, which are sometimes found in wet and sour lands, are precipitated by the ash and rendered innocuous or even beneficial. A good wood-ash fertilizer therefore is worth more than would be indicated by its commercial value calculated in the usual way.
230. Molasses from Sugar-Beets.—The residual molasses resulting after the extraction of all the crystallizable sugar in beet-sugar manufacture is very rich in potash. The molasses contains from ten to fifteen per cent of ash.
The composition of the ash varies greatly in the content of potash as well as of the other constituents.[191] The content of potassium carbonate varies from twenty-two to fifty-five per cent and, in addition to this, some potassium sulfate and chlorid are usually present.
The following figures give the composition of a good quality of beet-molasses ash:
| Potassium | carbonate | 45.30 | per cent | |
| Sodium | “ | 13.86 | “ | |
| Potassium | chlorid | 22.40 | “ | |
| “ | sulfate | 8.00 | “ | |
| Silica, lime, alumina, water, phosphoric | ||||
| acid, and undetermined | 15.82 | “ | ||
Thus, in 100 parts of such an ash over three-quarters are potash salts. The molasses may be applied directly to the soil or diluted and sprayed over the fields.
231. Residue of Wineries.—The pomace of grapes after being pressed or fermented for wine production contains considerable quantities of potash as crude argol or acid potassium tartrate. This material can be applied directly to the soil or first burned, when its potash will be secured in the form of carbonate.
The use of the winery refuse for fertilizing purposes has not assumed any commercial importance in this country.
232. Destruction of Organic Matter by Direct Ignition.—The simplest and most direct method for destroying organic matter is by direct ignition. The incineration may be conducted in the open air or in a muffle and the temperature should be as low as possible. In no case should a low red heat be exceeded. By reason of the moderate draft produced in a muffle and the more even heat which can be maintained this method of burning is to be preferred. With the exercise of due care, however, excellent results can be obtained in an open dish or one partly closed with a lid. At first, with many samples, the organic matter will burn of its own accord after it is once ignited, and during this combustion the lamp should be withdrawn. The ignition in most cases should be continued in a platinum dish but should the sample contain any reducible metal capable of injuring the platinum a porcelain vessel should be used. The lamp should give a diffused flame to avoid overheating of any portions of the dish and to secure more uniform combustion. In using a muffle the heat employed should be only great enough to secure combustion and the draft should be so regulated as to avoid loss due to the mechanical deportation of the ash particles.
233. Ignition with Sulfuric Acid.—The favorable action of sulfuric acid in securing a perfect incineration may also be utilized in the preparation of samples containing organic matter for potash determinations. In this case the bases which by direct ignition would be secured as carbonates are obtained as sulfates. In the method adopted by the official chemists it is directed to saturate the sample with sulfuric acid and to ignite in a muffle until all organic matter is destroyed.[192] Afterwards, when cool the ash is moistened with a little hydrochloric acid and warmed, whereby it is the more easily detached from the dish. The potash is then determined by any one of the standard methods. This method has several advantages over the direct ignition. Where any chlorids of the alkalies are present in the ash there is danger of loss of potash from volatilization. This is avoided by the sulfate process. Moreover, there is not so much danger in this method of occluding particles of carbon in the ash.
234. The Destruction of Organic Matter by Moist Combustion.—In the process of ignition to destroy organic matter or remove ammonium salts in the determination of potash, there are often sources of error which may cause considerable loss. This loss, as has already been mentioned, may arise from the volatilization of the potash salts or mechanically from spattering. In order to avoid these causes of error de Roode has used aqua regia both for the destruction of the ammonium salts and for the oxidation of the organic matter at least sufficiently to prevent any subsequent reduction of the platinum chlorid.[193] His method consists in boiling a sample of the fertilizer, or an aliquot portion of a solution thereof with aqua regia. The proposed method has not yet had a sufficient experimental demonstration to warrant its use, but analysts may find it profitable to compare this process with the standard methods. The organic matter may also be destroyed by combustion with sulfuric acid, as in the kjeldahl method for nitrogen. The residue, however, contains ammonium sulfate and a large excess of sulfuric acid, and for both reasons would not be in a fit condition for the estimation of potash.
It is suggested that the organic matter might also be destroyed by boiling with strong hydrochloric acid, to which from time to time, small quantities of sodium chlorate free of potash is added. Subsequently the solution could be boiled with addition of a little nitric acid and the ammonium salts be removed.