Proceedings of the Boston Society of Natural History 1: 123-128 (1843)

Composition of Corn

Dr. C. T. Jackson made a verbal communication on researches made by himself and Mr. A. A. Hayes, of Roxbury, respecting the saline and other ingredients of Zea mays, and other grains, exhibiting specimens of seeds to which Mr. Hayes' test of sulphate of copper, for the detection of the limits of the phosphates, had been applied. He also exhibited specimens to which tincture of iodine had been applied, which indicated the extent of the starch in. each kind of grain and in several other plants. Mr. Hayes' discovery of the limits of a salt of the peroxide of iron was demonstrated by soaking Indian corn in sulphydrate of ammonia.

The relative proportions of oil in the different varieties of corn was shewn by sections of the kernel, also the relative proportions of the zeine of Gorham or the gluten of corn. The causes of the peculiar explosion and evolution of the starch and gluten of corn in parching, was explained by the decomposition of the oil in the cells of the transparent portions of the grain.

Dr. Jackson had observed, in April, 1840, while analyzing the ashes of Indian corn, that after combustion of the corn in a platina capsule, at a high temperature, the platina was rendered brittle, and was in part converted into a phosphuret of that metal. On examining into the cause of this, he discovered phosphoric acid united to some volatile or destructible base, mixed with the phosphates of lime and of magnesia.

His subsequent researches satisfied him that the volatile base in question was ammonia, which he separated by the action of potash and lime, at a temperature below that required for charring the grain.

By the action of nitric acid, he burnt out the carbonaceous matter from the ashes of corn, and procured a considerable quantity of glacial phosphoric acid. In all these experiments, thus far, the whole grain was employed.

In May, 1842, Mr. A. A. Hayes, of Roxbury, exhibited to the chemical association some specimens of southern corn, which had been cut in two and soaked in a solution of sulphate of copper; and this test most beautifully marked out the limits of the phosphates in that grain. Profiting by this interesting experiment, and observing that the phosphates were indicated only in the cotyledon of corn, Dr. Jackson dissected out the cotyledons, analyzed them separately, and glacial phosphoric acid, phosphate of lime, phosphate of magnesia and ammonia were obtained. The proportions in the ashes of the whole corn was but 1 per ct. of phosphates of lime, magnesia and free phosphoric acid, and a little silica.

The cotyledons taken separately gave 6.4 per ct. of fusible matter, which ran freely when melted. It consisted of

Phos. lime 2.4
Phos. acid 3.2
Phos. magnesia 0.8

He also made an extensive series of researches on other seeds, both of the Monocotyledonous and Dicotyledonous plants, which determined the existence of the phosphates exclusively in their cotyledons. The specimens to which Mr. Hayes' test had been applied, and which were exhibited to the Society, were peas and beans of various kinds, squash and pumpkin seeds, horse chesnuts, the common chesnut, pea-nut, barley, oats, wheat, rye, buckwheat and cocoa-nut; also potatoe tubers and turnip bulbs. In all these the existence of phosphates was demonstrated.

In almonds, walnuts, butternuts, and most oily seeds, the sulphate of copper fails to demonstrate the presence of phosphates.

The application of tincture of iodine proved the presence and limits of starch in the turnip, and in several other plants which were exhibited.

A sample of the hard and transparent portion of Indian corn, from which the oil and zeine had been removed by alcohol and ether, was proved by the iodine test to be starch. It was observed that weak tincture of iodine does not color this portion of the corn until the oil is removed. If strong tincture of iodine is employed, the alcohol removing the oil causes the freed starch to take the blue color.

Beans and peas, consisting mostly of legumine, discovered by Braconnot, do not take a blue color like the starch containing grains, but become dark brown.

Specimens of various germinated and growing plants were also tested before the Society. In the potatoe sprout the starch was traced up into the plumule about half an inch, where it disappeared, and dextrine was present, the starch having undergone a metamorphosis into that substance. Similar experiments were tried on Indian corn, which had been grown about two inches high, in pure powdered quartz. The changes which the seed had undergone were quite interesting, and it was seen, by the iodine test, that the starch of the albumen had been absorbed, arid was changed in the plumule into dextrine and sugar. The portion of the corn, where the oil exists with starch and gluten, had begun to change, and iodine instantly forms a blue compound with the starch. On applying the sulphate of copper, the presence of phosphoric acid in the radicle and plumule, and a little around it, was readily proved.

On testing germinated English beans, the presence of phosphates was demonstrated in the cotyledons, but iodine did not prove the formation of starch from the legumin. The same experiment was performed with the common bean, with the same results. It will be interesting to study the changes which legumin, (a substance now supposed to be identical with caseine,) undergoes in the process of germination. As yet, we know of no chemical researches on its transformations in the living plant.

Dr. J. had observed that cucurbitaceous plants contained nitrate of potash, and had consequently directed its application around the roots of such vines. Observations on such plants grown on nitrous ground, where old barns had been removed, proved the value of that salt as a manure for squashes, pumpkins and melons.

Many important and interesting agricultural principles are to be discovered by investigations similar to these above noticed, but it may not be appropriate to lay any other facts before this Society than such as appertain to Natural History. It is evident that Organography and Physiology may derive much aid from the application of chemical tests to plants and their fruits. The subject is yet in its infancy, and we have much to expect when it shall become more mature.

Dr. Jackson exhibited to the Society a buff-coloured salt of lead, obtained by him, in 1841, from the maple sugar of commerce, by adding to its solution sub-acetate of lead.

This salt is humate of lead, and demonstrates the existence of humic acid in maple sugar, in which it was combined with ammonia and lime. March 18th, 1842.—Having procured some maple sugar made with care at Northampton, he repeated his researches, and discovered in it humic acid, apocrenic acid and crenic acid. These acids were proved to be combined, in part, with ammonia, which was separated by the action of hydrates of potash and of lime abundantly. Lime was also discovered in combination with crenic acid.

The same researches were made on brown, beet and cane sugars, and the same acids and ammonia were discovered, but in less quantity.

Mr. R. Soule, Jr., while a pupil in Dr. Jackson's Laboratory, made an examination of exhausted bone-black, to ascertain what coloring matters are retained by it. The substances detected confirm the researches of Dr. J. respecting the coloring matters of brown sugar. They were lime, apocrenic acid, crenic acid, humic acid, extract of humus and humin.

These facts were mentioned in his public lectures at the time, and they have been alluded to in the North American Review, in a notice of Prof. Hitchcock's Survey of Massachusetts.

We would call attention to this, because the same discovery has very recently been announced by Herman, of Moscow, and has been noticed in the New England Farmer as a discovery of much interest. The discovery is properly American, and Mr. Herman's researches have, independently, reached the same result, which must be regarded as confirmatory of Dr. J.'s.

He would remark, however, that he has, during the two past seasons, demonstrated, by the analysis of maple sap, that the organic acid which it contains is the glucic acid, which is in combination with lime as a biglucate. This is readily converted into crenic, apocrenic and humic acids by heat. Hence its origin in sugar. Specimens of all the substances mentioned in this communication were laid upon the table.

Dr. Jackson remarked, that he had satisfactorily proved, that the gluten of Indian corn, or the zeine of Gorham, contained 5 per ct. of nitrogen, which was naturally overlooked at a time when the means for exactly separating that element were unknown. Corn also contains 6 per ct. of oil.

The following reflections naturally suggest themselves, on considering the ingredients of Indian corn:

These ingredients, common also to other cereal grains, explain to us why they have been justly called the "staff of life."

Analysis of the Raspberry Bush:

Having noticed that the raspberry bush sprung up wherever fields had been burnt over, and also by the side of decomposing stone walls, Dr. J. was led to analyze it, with the expectation of finding an unusual amount of potash.

The following are the results of the analysis of the Rubus strigosus: 1000 grains of the dry raspberry bushes were burnt in a platina dish, in a muffle, and the ashes collected in this manner were found to be burnt perfectly free from carbon. The amount of ashes from 1000 grains of the bushes was 16.2 grains, or 1.62 per ct. It was easily melted, and flowed in the capsule. The fused ashes, analyzed in the usual manner, yielded

Silicic acid 0.25 or per ct. 0.025
Phosphate of Lime 3.65 " 0.365
Carbonate of Lime 3.40 " 0.340
Potash 5.24 " 0.524
Soda 0.50 " 0.050
Ox. Manganese 1.00 " 0.100
  14.04   1.401
Carbonic acid 2.16    
  16.20