STARCH-PRODUCING PLANTS INVESTIGATED.

Starch is one of the constituent parts in all mealy farinaceous seeds, fruits, roots, and other parts of plants, and is in large demand for domestic use, the arts, &c. Our common starch is made from wheat, and a good deal from potatoes. Pure fecula is separated by art from a variety of plants.

The bread fruit (Artocarpus incisa), already alluded to, yields a large quantity of starch; as do the sweet potato (Convolvulus Batatas, or Batatas edulis). The pith or farinaceous part of the trunk of the Caryota urens, is almost equal to the finest sago. In Assam the sago of this palm is much used.

The two varieties of the Cassava afford a very superior fecula, which is imported under the name of Brazilian arrowroot. 8,354 bags of tapioca and farina were imported from Maranham in 1834. Some excellent starch from Norfolk Island was shown at the Great Exhibition.

The Cycadaceous family yields much starchy matter, along with mucilage. From the soft stems of Cycas revoluta and C. circinalis, natives of China and the East Indies, a kind of sago is made. These plants are propagated by suckers. Zamia pumila, a native of the Cape of Good Hope, and other species of this remarkable genus of plants, which is nearly related to both ferns and palms, supply an amylaceous matter, which has been sold as arrowroot. A similar product is obtained from Alstrœmeria pallida, a perennial plant, with pink red flowers, growing in Chili. From the nuts of the Cycas circinalis, the Singalese prepare an inferior kind of starch, by pounding the fresh kernels. These are cut in slices, and well dried in the sun before they are fit for use, otherwise when eaten they are intoxicating, and occasion vomiting and purging.

The quantity of starch in a plant varies according to the period of growth. The results of examination on the comparative yield of starch in the potato, showed that while it abounded towards the latter part of the season, it decreased when the tubers began to germinate in the spring. It was found by Professor Balfour that 240 lbs. of potatoes left in the ground, contained of starch—

The quantity of starch remained the same during the dormant state of winter, but decreased whenever the plant began to grow, and to require a supply of nourishment.

This table exhibits, no doubt, very unexpected results, since it places the sweet cassava at the very top, and the banana at the lowest place in the list, while the bitter cassava, which seems to be little more than a variety of the sweet, notwithstanding its being the staple material of West Indian bread, occupies two places lower down, and is followed by the plantain. The sweet potato and the yam, both of which are considered to be less nutritious than the arrowroot, rank above it in the centesimal proportion of their amylaceous produce. Upon what, then, do the nutritive properties of these various substances depend? Is it upon a gluten which was overlooked by Mr. Harris, in his experiments, or, if not, may we not suspect some inaccuracy in the proportion of starch assigned by him to each? It is to be wished that similar experiments were repeated with care in different quarters, and the list extended to other tropical products applicable to human sustenance, especially the roots which yield the farinaceous starch of the South Sea islanders, to the achira of Choco, &c.

I shall extract largely from a very valuable report drawn up by Dr. John Shier, agricultural chemist, of Demerara, and submitted to the Governor of that colony in 1847, on the starch-producing plants, which is deserving of more widely extended publicity than the merely local circulation it has received. The remarks and results of experiments are worthy of deep consideration; and although they were meant to apply specially to British Guiana, they are equally pertinent to the West India colonies generally, our African and Australian settlements, and many other of our foreign possessions.

It has been ascertained, in regard to some plants at least, that a much larger return can be obtained in the colonies than can be grown in temperate countries, however fertile. This is partly owing to the greater fertility of the soil under powerful tropical atmospheric influences, and partly to the fact that vegetation is continuous throughout the year, so that slow growing plants can do more within the time, from their functions not being arrested by the chill of winter; and of many rapidly growing plants, two successive crops can be grown within the year.

Starch is a substance easily manufactured, and being largely used in several of the arts, as well as an article of diet, there consequently exists a considerable demand for it in England. It may be obtained from a great variety of plants, and many of the most productive of it are natives of the tropics.

The high prices commanded by grain and breadstuffs in Europe, renders the present a remarkably favorable time to ascertain what can be done in this branch of tropical agriculture; for should the potato disease return, or this root be less extensively planted than hitherto, starch must maintain a high price, and it will be worth ascertaining whether some of the superior starch-producing plants of the tropics might not be cultivated to such an extent as to supply the English market, and thus be at once profitable to the colonies and advantageous to the mother country.

Before entering on such a cultivation, however, various points require investigation. We ought to be able to answer such questions as the following:—

In the following observations (continues Dr. Shier) I shall be able to reply to several of these questions, especially those capable of being settled in the laboratory. On other points, particularly those relating to the returns per acre, I am at present but imperfectly informed, in consequence of the limited extent to which these plants have hitherto been cultivated in this colony (Demerara), and from the total absence of authentic data regarding the amount of yield.

Characters of starch produced from different plants.—Starches from different plants are best distinguished from one another by examination under a good miscroscope. The grains or globules may be examined either as transparent or opaque objects; and although in the same species there are considerable differences in size and form, the different kinds are, on the whole, quite distinguishable. One of the best ways of examining the form of the globules, under the microscope, is to lay them on a plate of glass and cover them with a drop of aqueous solution of iodine, which renders them gradually blue and opaque. When the difference in size and form between the globules of different species is considerable, as between the Tous les mois starch and cassava starch, or even between the arrowroot starch and cassava starch frequently used to adulterate it, it is not difficult, with a little practice, to detect the fraud.

From an inspection of this list, it does not appear that the species would be easily distinguishable, and it is not easy briefly to describe the differences; in practice, however, and especially when the observer has a number of pure and authentic specimens before him, to have recourse to as standards of comparison, the discrimination is by no means difficult.

Specific gravity of starch derived from various plants.—Of many bodies the determination of the specific gravity is one of the best modes of distinguishing the purity. With the view of ascertaining whether the different varieties of starch have all the same density, as has been asserted by some, trials were carefully made of as many specimens as I could procure. The results are embodied in the following table:—

From this it will be seen that the order of density does not correspond with the order in any of the other tables. Probably those specimens prepared from dry seeds, such as wheat and maize starch, which, as commercial articles at least, are less pure than those prepared from recently dug roots, have also the lowest density.

Hygroscopic properties of starch produced from different plants.—Such of the specimens as are marked in the following table, as prepared in the colonial laboratory, were dried in the sun in shallow trays, to which they had previously been transferred in the wet state. When sun dried, the masses were broken down, and the starches freely exposed to the air in the shade for ten days. Any adherent masses were then rubbed to powder by light pressure in a glazed mortar, and the whole sifted. Portions of each of these starches, and of others for the sake of comparison, were then dried, at 212 degrees Fahrenheit, in a current of dry air, and the loss determined:—

That the extremes in this table should occur in the case of the starches of commerce, was, perhaps, to be expected; nevertheless the difference between the starch of the sweet potato and that of the bitter cassava is nearly as great, and both these specimens were prepared in the laboratory, by the same process, and subject to the same temperature and exposure.

Characters of the jellies formed by various starches.—Tenacity.—I have met with no very precise results on this subject, except the well-known fact that it takes a much larger quantity of some starches, the arrowroot for instance, to form a jelly of equal tenacity with that formed by others, such as the Tous les mois; and hence in the West Indies the latter is universally preferred to the cassava starches.

The following statement shows the results on such specimens as I could procure. The disc was exactly 7/10ths of an inch in diameter.

From this list it is obvious that, in respect of tenacity, there is a very great difference between the jellies prepared from the different starches—greater, indeed, than exists in regard to any other character. At first I thought it probable that the tenacity of the jelly would bear some relation to the size of the globules, and it is true that we find the Grenada Tous les mois, the largest globule, next the top, and the cassava among the smallest, at the bottom of the scale. But, on the other hand, we have the Buck yam starch, a large sized globule, very high; together with many other exceptions.

As an article of diet, the most tenacious varieties of starch are preferred, on account of the economy of employing an article of which a less quantity will suffice; and the same is true when applied to starching linen, provided the jelly be not deficient in clearness.

On comparing this list with the former one, and taking a general view of the subject, it will be seen that the jellies that are most tenacious are generally the least translucent, and that the order of the two lists is more nearly the converse than occurs in regard to any other properties.

Percentage of starch yielded by different plants.—On this point no two writers do or can agree. The quantity of starch, even in the same plants, the potato for instance, varies with the season, the soil, climate, age, ripeness, length of time the roots have been out of the ground, &c.

In the following table I have given the result of a series of trials made in the Colonial Laboratory, Demerara. The roots were all fresh dug, and, with two exceptions, noticed in the remarks, were fair average specimens. The process was the common one. The grater or rasping machine was of copper, to avoid injuring the color of some of the starches, which an iron grater is liable to do:—

From the foregoing list it appears that the sweet and bitter cassava merit attention as starch-producing plants. They are occasionally grown for this purpose in the colonies, and yield a large per centage of starch; but there exists an opinion, whether well or ill founded, that it is liable to rot linen, and the preference is given here to the starch of arrowroot. It remains to be seen, however, what estimate will be formed of this starch in England, for if it should prove an esteemed variety, there can be no doubt of its proving a highly profitable cultivation. Cassava grows readily in almost any soil, and when the drainage is tolerable, two crops of the sweet variety can, it is stated be grown in a year. I have seen it growing luxuriantly in the light soils of the interior, as well as in the stiff clay soils of the coasts. It is considered an excellent preparatory crop in new and stiff land, on account of its tendency to loosen the soil. Were the bitter variety fixed on, the preparation of Casareep might be combined with the preparation of starch; and as that substance is one of the most esteemed bases for the preparation of various sauces, it is probable that this might turn out the most profitable part of the produce. At all events, bitter cassava would have this advantage over all other starch-producing roots, that the juice of the roots could be turned, to account as well as the starch.

Of all the plants mentioned in the list, starch is most readily separated from the arrowroot, in consequence of the tissue being more fibrous, and yielding little or no cellular tissue requiring to be run off the starch. Time and water are thus saved in the process, and were the fibrous residue pressed and dried, it could probably be turned to good account in the manufacture of paper.

In respect of facility of preparation, the plantain starch, though of excellent quality, ranks lowest, for the flesh-colored tissue in which the starch is embedded is somewhat denser than the starch, and settles down under it, and it is not a little difficult to arrange the process so as completely to separate the finer parts of this matter from the starch, and hence its color is never perfectly white.

Yield of starch-producing plants per acre.—On this subject, as already remarked, I do not at present possess sufficiently accurate data.

Of the yield of the plantain we possess much more accurate information. A new plantain walk in this colony (British Guiana) will yield 450 bunches, of 50 lbs. each, of which, as nearly as possible, 50 per cent. will be of core, containing 17 per cent. of starch, thus producing 17 cwt. of starch per acre. But an old plantain walk, even when free from disease, could not be reckoned to yield more than half this quantity, namely, 8½ cwt. per acre. Considering the value that is set on the plantain as an article of food, and the difficulties incident to the process of making starch from it, it is by no means probable that it will ever be used as a source from which to obtain starch.

Of the quantity of arrowroot that can be grown per acre, I have been able (continues Dr. Shier) to procure no information; but from the price it commands in the market, the facility with which it can be grown, and the ease with which the process of separating the starch can be carried on, it deserves a fair trial here. To cultivate it to advantage it ought to be done on thorough-drained and well-tilled land, planted at the proper season, and not dug till ripe and in dry weather.

Of the Tous les mois, I have only been able to procure a single plant, for which I am indebted to the kindness of the Hon. John Croal. As the root was immature, it would be unfair to deduce from the quantity of starch obtained, the per centage generally contained by the plant. Its immaturity was also indicated by the globules being smaller than in the specimen obtained from Grenada; in other respects, however, such as the tenacity of its jelly, it stands highest. It is altogether one of the most promising starch-producing plants, and obviously deserves a careful trial. It is a plant that expends a good deal of matter in maturing a considerable quantity of dense and bulky seeds, but as it propagates both by root and seed, it is probable that, as a root-crop, it would be highly advantageous to procure a variety that does not flower.

Both the tannia and the sweet potato can be readily grown, and the produce per acre is large; but from the foregoing tables it would appear that there are other plants whose starch is likely to be held in greater estimation.

The creek water of the colony is generally too brown, and the trench water too muddy, and contains often too much salt to produce starches of the finest color, hence recourse would require to be had to rain water, or Artesian water. The first is remarkably pure, and it certainly does not appear that were sufficiently capacious reservoirs built, or ponds dug, and protected from infiltration by the usual well-known means, there would be great difficulty in getting a sufficient supply of rain water. It is done in Bermuda, and why not here? On the other hand, almost all the Artesian wells in the colony contain a large quantity of oxide of iron held in solution by carbonic acid, and which separates as an ochrey deposit on free exposure to the air. Were this water used in the starch process, it would certainly injure the color materially; but by a chemical process, exceedingly simple, inexpensive, and easy of application, it is possible to purify the Artesian water, and render it almost as fit as rain water for the purpose of manufacturing starch.

In some of the other colonies a great deal of the best starch is produced by the holders of small lots of land, and many parts of the labor being light, and suited for women and children, it is one of the most desirable cultivations for small holders, and would be very beneficial for Demerara, where the lands of the peasantry too generally lie in a state of utter neglect; yet small holders could not be expected to be able to compete with those who should grow starch on the large scale, and prepare it with the best machinery.

Cassava meal, plantain meal, &c., as articles of export.—It may soon become an important question whether the plantain, or some of the edible roots grown in the tropics, might not be sent to Europe in a fresh state as a substitute for the potato. Many of them, the buck yam and the cassava, for instance, ought to be used when fresh dug, for every day they are out of the ground they deteriorate. This, however, is not so much the case with some of the larger yams. It is worth trying whether the finer sorts that deteriorate by keeping, might not, after being sliced and dried in the sun, become articles of export, either in that state or when ground to meal. For this purpose the bitter cassava, the plantain, and the buck yam are the most promising.

If an acre of well-tilled thorough-drained land yield 10 tons of fresh roots, and I have every reason to believe that such a return might be obtained, I have ascertained that the produce would be 3½ tons of meal, 598 lbs. of casareep, and 2 cwt. of starch; and estimating the meal at 1d. per lb., the casareep at 1s. 5d. per lb., and the starch at 40s. per cwt., the gross amount would be £78 13s. 4d. per acre. In ascertaining these proportions, very simple machinery was employed, and had the pulp been better pressed the quantity of casareep would have been considerably greater.

From the table given in a former note it will be seen that the cassava meal prepared in this way contains but a very small proportion of matter nutritive in the sense of contributing to the formation of blood, and that the expressed juice carries off fully one-half of the proteine compounds contained in the plant.

Lichenin is a variety of starch occurring in Cetraria islandica, or Iceland moss.

Indian corn starch.—The advance of science has recently brought to our knowledge the preparation and use of another article, not only important as food, but also essential in the arts. I have had occasion to mention the high value of the Indian corn, and I might with advantage allude to many of its uses and properties; at present I must confine my remarks to a product from this valuable grain, known as corn starch, and yet another as the fecula of maize. In the close of 1849, Mr. Willard and his associates, of Auburn, established extensive works at Oswego, for the preparation of these important products, their establishment covering an area of 49,000 square feet. As the proprietors have to some extent held unrevealed the process by which they produce a starch more pure than the starch of commerce, we may not indulge in speculative curiosity; yet I can hardly doubt their great success is mainly attributable to perfect machinery, guided by science and talent. The rapid and extended demand for these new products presents sufficient evidence of their character, as we are told that about three millions of pounds of this corn starch are demanded annually by the trade, notwithstanding the usual supply of wheat starch is undiminished. A remarkable feature of maize starch is the absence of impurities; upon being subjected to analysis, it is found that only 2 76-100 parts in 1000 are of other matter than pure starch. According to Dr. Ure, wheat yields only 35 to 40 per cent, of good starch, a material extensively used in arts and manufactures.

The Oswego starch factory has happily introduced the use of Indian corn, as a grain producing a larger proportion of pure amylaceous properties than any other known vegetable substance, proffering to the American manufacturer another economic advantage, sustaining, in a most legitimate matter, sound rivalry and competition with all the world. I am not aware whether the Oswego factory has converted its starch into gum—a process easily accomplished by heat, and thus rendered soluble in cold water, which cannot be done while in its condition of starch. Here is another result of vast importance derivable from Indian corn; and we can well conceive that, in a short period of time, the advantages now derived from the production of corn starch, may have grown into a national benefit.

Rice (according to Prof. Solly) contains on an average about 84 per cent of starch; but till comparatively a few years ago, no starch was manufactured from it, notwithstanding its low price, and the large quantity of starch which exists in it. The reason of this was, that the old process of fermentation, by means of which starch is procured from grain, was not found to be applicable to rice; and hence the latter only became available as a source of starch in 1840, when Mr. Orlando Jones introduced his new process, for which he obtained a patent. This process consisted in macerating the rice for about 20 hours in a dilute solution of caustic potash, containing about 200 grains of the alkali in every gallon; the liquor is then drawn off, the rice dried, reduced to powder by grinding, then a second time digested in a similar alkaline lye for 24 hours, repeatedly agitated. After this it is allowed to settle, and well washed with pure cold water. A prize medal was awarded for this rice starch at the Great Exhibition.

ARROWROOT, EAST AND WEST INDIAN.

The genuine arrowroot of commerce is the produce of the tuberous rhizomata of Maranta arundinacea, a native of South America, and M. indica, indigenous to the West Indies, but also cultivated in the East. The best West Indian arrowroot comes from Bermuda. Its globules are much smaller and less glistening than those of Tous-les-mois, or potato starch.

The peculiar characteristics of the starch obtained from various plants has been particularised and described already in the elaborate investigation of the commercial yield and value of the starch-producing plants. Amylaceous matter of a similar kind to arrowroot is obtained from other species of Maranta, as from some species of Canna, well known under the popular name of Indian shot, from the similarity of their round black seeds.

The arrowroot plant (M. arundinacea) is a perennial, its root is fleshy and creeping, and very full of knots and numerous long white fibres. Arising from the root are many leaves, spear-shaped, smooth on the upper surface and hairy beneath. The length of the leaf is about six or seven inches, and the breadth about three towards their base, the color and consistence resembling those of the seed. From the root arise slender petioles upon which the leaves stand, and several herbaceous erect stalks come out between them, rising to the height of about two feet. A loose bunch of small white flowers is succeeded by three-cornered capsules, each containing one hard rough seed.

The propagation and culture of this plant are of the simplest kinds. The roots should be parted, and the most suitable soil is a rich loam.

In the Bermudas, a deep rich soil, or one in which marsh or peat prevail, is alone adapted for growing arrowroot in perfection.

A correspondent from the Bermudas, (where arrowroot forms the great staple crop of the islands), informs me that he ploughed up a small piece of land, twenty rods (or the eighth part of an acre), with a small plough and one horse. He ploughed it over three times, and the third time planted the arrowroot as he ploughed it. The land had not been turned up before for twenty years.

The expenses and profits stand thus:—