foundery, I had the opportunity of making my potassium there, as I could apply the blast from the smelting furnace to my apparatus, and then I got it in considerable quantity. I generally laid two barrels parallel to each other through the furnace, and thus got once nearly two ounces; but I repeat, that without being able to give a very high degree of heat, it is not worth while going about making potassium, as the quantity obtained will be very trifling. For a lute, to cover that part of the barrel which comes in immediate contact with the fire, I tried mixtures of pure clay with sand in different proportions; but none of them answered my purpose so well as the clay by itself, which is found near Moscow, and used for crucibles all over Russia; it is known in commerce by the name of Moscow clay. Using this clay, I could give almost any degree of heat that can be procured from charcoal (which I always used, we having no coal in St. Petersburgh), without melting the barrel. The open ends of the barrels were placed under oil in one small bason; and after the operation was finished, I simply corked them, in order to prevent the air getting in, till I had cut off the under parts of the barrels, in order to obtain the potassium also which was collected there. This latter is, as I have said before, always less fusible, and alloyed with iron, whereas the other, which does not remain for any time in contact with the iron barrel, runs down into the oil, which absorbs the oxide, which might be on its surface, forming a soap with it. This potassium was the purest I ever obtained. I used to keep it in small glass tubes, in which I pressed it close towards the inside of the glass, and the tubes being hermetically sealed. I am, dear Sir, yours most faithfully, Glasgow, March 15, 1815. J. HAMEL, M. D. ARTICLE VIII. Description of a Machine for the speedy Separation and Manufacture of Farina or Flour from Potatoes, and for various Observations relative to the Necessity of encouraging an extended Growth of Potatoes, and for their Applications, in various States, to make Sea Biscuits, Bread, Pastry, &c. By John Whately, Esq. of Cork. With a Plate.* Ir is naturally the first object, and forms the primary duty of a well-regulated state, to provide its members with a sufficient quantity of good food. The greater are the advantages, and the * From the Transactions of the Society for the Encouragement of Arts, Manufactures, and Commerce. The lesser gold medal was voted to Mr. Whately for this invention. more independent is the situation, of that country which can furnish within itself a full and ample supply of the means of subsistence to its inhabitants. We have long ceased in this country to feel the benefits arising from such a state of independence, and we have during the last 10 or 15 years incurred a very large expenditure in the purchase of foreign corn. This subject has engaged much, of my attention; and I have endeavoured to devise a plan by which the agriculture of this country may be improved, a great expenditure saved, and a considerable reduction of prices effected, by the introduction into bread of an article of known nutritious properties derived from the potatoe. This substance is the farina or flour of that valuable root, which I have tried with advantage to a very great extent, having previously gone through a long course of experiments on making bread, biscuit, and pastry, from mixtures of raw potatoes, and boiled potatoes and farina, with different proportions of flour, &c. It is well known that poor light soils, unfit for the culture of wheat, and from which only crops of barley or oats have been produced, and of which, in many situations, there are large tracts of land altogether uncultivated, will produce potatoes of excellent quality two circumstances have, however, hitherto prevented their culture to the desirable extent, namely, the great expense of their carriage in a raw state from the interior parts of the country to a proper market, and their not keeping well more than six months after the crop is gathered. These inconveniences I have obviated by the invention of a machine which is now at the Society's house, by which one individual can grind down 15 hundred weight, or 1700 lbs. net of potatoes, into soft pulp in one day, yielding about two hundred weight of farina or flour when dried. By calculation, the power of a single horse will be equal to the grinding of 22 tons of potatoes per week; the machine is capable of being applied to any power required. The farina or flour has been known to keep good 17 years; and it may be afforded so as to yield a fair profit to the farmer and the manufacturer at 3d. per lb. The present price of wheaten flour is about 54d. It would be tedious now to enter into a long detail of this business by letter; but my son is in London; and if he is permitted to attend a Committee of the Society, and to give proofs of the trials I have made, by exhibiting specimens of the bread, flour, and biscuits, and by furnishing such other particulars as may be required, I trust they will perceive the great benefits that may result from this article, and particularly if my communications should merit the sanction of the Society, and be honoured with their approbation. Remarks from Mr. Whately on Potatoes. It may not be generally known, but it is capable of the most satisfactory proof, that the same quantity of land will yield above one half more of farina or flour where potatoes are cultivated, than if the same land was applied to the production of flour from wheat. I have proved from experiment, that 2619 lbs. of pure farina or flour may be produced from an acre of land planted with potatoes, and only 1660 lbs. of flour from an acre of wheat. It will therefore be obvious that, if we can apply this great excess to the same purposes as the flour of wheat, the advantages arising from it will be of the highest importance to the community. We now require from foreign countries about 500,000 quarters of wheat annually, for which we incur an expenditure of about two millions sterling, in ordinary years, and which has increased in years of scarcity to upwards of seven millions sterling, and there seems no probability that, under the continuance of the present system of cultivation, we shall ever arrive at the period when we can supply our own wants, and feel independent of foreign aid for one of the first articles of subsistence. We have had for the last ten years not only a course of favourable seasons, but the farmer has had in the greater part of that period the benefit of high prices to stimulate his exertions to the greatest possible production of corn; and if they have failed, under such favourable circumstances to satisfy our wants, what evil may we not expect if the seasons should prove unpropitious, and the inconveniences of our situation aggravated by scarcity? I admit that the prospect of supplies from foreign countries may be great; but we should recollect, that only a few months have elapsed since the ports of Europe and America were shut against us, or only open on a system of license, and that in a situation of dependance which no well-wisher to his country can be desirous to see recur, nor the possibility of which he will not feel anxious to prevent. This, then, is one of the advantages which will attend the consumption of potatoe flour in bread; the earth yields it so much more abundantly, that the very first year's cultivation of potatoes for that purpose, to the extent of only 25,000 acres, would relieve us from the necessity of any foreign importation, and instead of importing, we should speedily become an exporting country. Potatoes are found to possess such highly nutritive properties, that it seems hardly necessary to enter upon that subject. They constitute, it is well known, in their natural state, the principal food of the Irish, and they are daily forming a great part of our own. This farina or flour, which contains the substantial nourishing properties of the root, deprived of its watery particles, cannot but be highly nutritrious; the use of it, therefore, in bread, is not likely to be the subject of dispute, provided it is in that state palatable, and can be afforded at a price not exceeding the price of wheaten flour. That it possesses the first-mentioned property, I have only to refer to the bread produced to the Society, containing different proportions of this flour, any, and all of which will, I believe, be found as wholesome and agreeable as bread made wholly of wheaten flour. VOL. V. N° V. Z |