852 PRACTICE OF AGRICULTURE. Pari III. 



Tb keep potatoes oaf length ol thru, the mod effectual way is to place them In thin layen on a 

 platfbrm suspended in an Ice cellar. There the temperature being always below that of active vegetation, 

 the* will not sprout; while nol being above one or two degrees below the freezing point, the tubers will not 

 be (roil bitten Another mode li to icoop oul the eyes with a verj small scoop, and keep the roots buried 

 Inearth. \ iiiir.i mode is to destroy the vital principle by kiln-drying, steaming, or scalding A fourth 

 mode Is to bury them so deep Indn soil thai no change "t temperature will reach them, ami consequently, 

 being without air, they will remain upwards of a year without vegetating. 



18. The produce of the potato varies from five to eight, and sometimes ten or twelve 

 tons per aire ; the greatest produce is from the yam, which lias been known to produce 

 twelve tons, or ISO bushels per acre. The liaulm is of no use but as manure, and is 

 sometimes burned for thai purpose, being slow of rotting. 



5349. The mast important application of the potato crop is as human food ; on this it is 

 unnecessary to enlarge. 



Ein/i(ttrfi»iinl mealy potatoes to contain twenty-four per cent, of their weight of nutritive matter, 

 and rye seventy parts : consequently, sixty-four and a half measures of potatoes atlbrd the same nourish. 

 ment as twenty-four measures of rye. A thousand parts of potato yielded to Sir II. Davy from 200 to L'fJl 

 parts Of nutritive matter, of which from 155 to 200 were mucilage or starch, fifteen to twenty sugar, and 

 thirty to forty gluten. Now, supposing an acre of potatoes to weigh nine tons, and one of wheat one ton, 

 which is about the usual proportion; then as 1000 parts of wheat afford 850 nutritive parts, and I00U of 

 potato M») - ". the quantity of nutritive matter afforded by an acre of wheat and potatoes will be nearly as 

 nine to four | so that all acre of potatoes will supply more than double the quantity of human food afforded 

 In an acre of wheat The potato is perhaps the only root grown in Britain which may be eaten every day 

 in the year without satiating the palate, and the same thing can only be said of the West India yam and 

 bread fruit They are, therefore, the only substitute that can be used for bread with any degree of success ; 

 and indeed they oi'ten enter largely into the composition of the best loaf bread without at all injuring either 

 its nutritive qualities or Savour. {Edin. Encyc art. Baking.) In the answer by Dr. Tissot to M. Lanquet, 

 the former objects to the constant use of potatoes as food, not because they are pernicious to the body, but 

 because they hurt the faculties of the mind. He owns that those who eat maize, potatoes, or even millet, 

 in. iv grow tall and acquire a large size ; but doubts if any such ever produced a literary work of merit. It 

 dues not, however, by any means appear that the very general use of potatoes in our own country has at all 

 impaired' either the health of body or vigour of mind of its inhabitants. 



5351, The manufacture of potato flour is carried on to a considerable extent in the neighbourhood of 

 Paris, and the Hour is sold at a price considerably higher than that of wheat, for the use of confectioners 

 aiid for bakers who prepare the finer sorts of bread. The potatoes are washed and grated, and the starch 

 separated from the pulp so obtained by filtration; it is dried on shelves in a mom heated by a Hue. and 

 afterwards broken on a floor by passing a cast iron roller over it. It is then passed through a bolting 

 machine and put up in sacks for sale. The most complete manufactory in the neighbourhood of Paris in 

 ls.'i was that of M. Delisle at Hondy. {Gard. Mag. vol. vi.) Most of the operations there are performed 

 by a steam engine attended by children. It is reported by the fount de Chabrol, in his Statistical Account 

 of Paris, that +o,000 tons of potatoes are annually manufactured into flour within a circle of eight leagues 

 around that lit v. . , ,. , 



i 3 ,:. The quantify of farina which potatoes produce varies not only according to the species, but accord 

 ing to the period when the extraction takes place. The variations produced by this last cause are nearly 

 as follows : Two hundred and forty pounds of potatoes produce of farina, or potato flour, in 



August, from 23 to 2.") pounds. March from 4.5 to 38 pounds. 



Sept 32 ... 38 April 38 ... 28 



Oct 32 ... 40 May 28 ... 20 



Nov 38 ...45 



The extraction of the farina should be discontinued at the period when the potatoes begin to grow, the 

 farina being destroyed by germination. Red potatoes produce a smaller quantity of farina. Those which 

 are blue on the outside give little, but it is of good quality ; the white, which is often tinged with red in 

 the interior, is the least proper for this extraction. The best of all is that which has a yellow tint, as its 

 farina is of very good quality, and abundant. [Hygie de Ilru.ielles.) 



5 153 Potato flour is made into bread in a very simple manner. Its adhesive tendency does not admit of 

 baking or kneading unmixed with meal or wheaten Hour ; but it may be made into cakes in the following 

 manner:— A small wooden frame nearly square is laid on a flat pan like a frying-pan; this frame is 

 grooved, and so constructed, that, by means of a prcsser or lid introduced into the groove, the cake is at 

 once fashioned according to the dimensions of the mould The frame containing the farina may be almost 

 immediately withdrawn alter the mould is formed upon the pan ; because, from the consistency imparted 

 to the incipient cake by the heat, it will speedily admit of being safely handled. It must not, however, be 

 fired too hastily, otherwise it is apt to become unpleasantly hard and unfit for mastication. This pre- 

 cautionary measure being observed, it will be found, that, where thoroughly ready, the bread of potato 

 flour even unaided by anv foreign ingredient, will eat very palatably. It might thus, from time to time, 

 be snaked for puddings, fike the tapioca ; or it might be used like the cassada-cake, which in appearance 

 and quality it so much resembles; that is, when well buttered and toasted, it will make an excellent 

 breakfast appendage. [Quar. Journ. Apr. vol ii. p. 69.) 

 •5354 The meal of potatoes mavbe preserved for years closely packed in barrels, or unground in the form 

 of slices ; these slices having been previously cooked or dried by steam, as originally suggested by Forsyth, 

 nf Edinburgh. (JEncyc. Brit.) Some German philosophers have also proposed to freeze the potato, by 

 which the feculent matter is separated from the starch, and the latter being then dried and compressed, 

 may be preserved for any length of time, or exported with ease to any distance. {Annalcn des Aclarbaues, 



vol hi. s.389.) , . ' . 



The manufacture of tapioca from potatoes is thus given in the Quarterly Journal Of Agriculture. 

 The potatoes selected are thoroughly washed, after which they are grated in a machine constructed for 

 the purpose. The parts thus reduced or grated fall into a vessel placed underneath. From this vessel 

 they are removed, and strained into a tub. On the juice being well expressed for the first time, the fibrous 

 matter is set apart, and cold clean water is thrown over them. These fibres are again put through the 

 same strainer, till the whole of the substance is collected, when they are finally cast aside. On this being 

 done the contents of the tub, now in a state of mucilage or starch, are allowed to settle. A reasonable 

 interval being .suffered to elapse, the old water is poured gently oil', and fresh water supplied. After this 

 process of fining and washing, the blanched matter is passed through a smaller strainer. 



55.56 The offals are separated. The starch becomes now much whiter ; still fresh water is abundantly 

 dashed over it. When by frequent ablution the surface of this vegetable mass is rendered quite smooth 

 and clean, it is filtrated a third and last time. ...... 



The strainer now used is of very fine texture, so that no improper or accidental admixture may 

 interfere As soon as the starch, thus purified, has firmly subsided, it is spread on a board, and exposed 

 to the open air. The damp speedily evaporates, on u Inch it is, as a security tor cleanliness, put through a 

 sieve. 



