PRUSSIATE OF POTASH.

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square walls or body of the oven; b, the partition wall; c, the fireplaces or furnaceswith their iron boilers ; d, the mouths of the furnaces for introducing the fuel; /, tl* eash-pits; g, the horizontal flues under the hearth of the oven; h, the vertical flues;i, the vents in the top of the arches; and fo, the entrances to the chambers of theovens.

PRUSSIAN BLUE . The following process deserves peculiar notice, as the fir stin which this interesting compound has been made to any extent, independently olanimal matter. Mr. Lewis Thompson, of the Old Barge House, Lambeth, received awell-merited medal from the Society of Arts for this invention. He justly observes)that in the common way of manufacturing prussiate of potash, the quantity of nitrogenfurnished by a given weight of animal matter is not large, and seldom exceeds 8 P e ‘cent.; and ol' this small quantity, at least one half appears to be dissipated^luring th eignition. It occurred to him that the atmosphere might be*economicaIly made to suP'ply the requisite nitrogen, if caused to act in favorable circumstances upon a mixtureof carbon and potash. He has found the following prescription to answer : Take orpearlash and coke, each 2 parts; iron turnings, I part; grind them together into a coarsepowder; place this in an open crucible, and expose the whole for half an hour to a f®red heat in an open fire, With occasional stirring of the mixture. During this p 10 'cess, little jets of purple flame will be observed to rise from the surface of the material 5 'When these cease, the crucible must be removed and allowed to cool. The mass is 10be lixiviated; the lixivium, which is a solution of ferrocyanide of potassium, with e!£ "cess of potash, is to be treated in the usual way, and the black matter set aside ft> r ® .fresh operation with a fresh dose of pearlash. Mr. Thompson states that 1 pound opearlash, containing 45 per cent, of alkali, yielded 1,355 grains of pure Prussian blue ,or ferrocyanide of iron ; or about 3 ounces avoird.

PRUSSIATE OF POTASH. Leuch’s Polytechnic Zeitung, June, 1837. Manufac-ture of Kalium Eisen Cyanure, by Hofflmayr and Prtikner.—The potash must be b e .from sulphate, for each atom of sulphur destroys an atom of the Eisencyankalium. jvery strong heat is advantageous. The addition of from 1 to 3 qy of saltpetre is usef u ’when the mass is too long of fusing. A reverberatory furnace (flammofen) is recoupmended ; but the flame must not heat too much upon the materials, for fear of oiigenating them. When the smoky red flame ceases, it is useful to throw in from ti®to time smaU portions of uncarbonized animal matter, particularly where the flame nbeats upon the mass, whereby the resulting gases prevent oxidation by the air. *■ ,animal matters should not be too much carbonized, but left somewhat brown-colo re ’provided they be readily pulverized. Of uncarbonized animal matters, the proport®may be 100 parts dried blood, to from 28 to 30 of potash (carbonate), and from 2 to 4hammerschlag (smithy scales), or iron filings; 2, 100 parts of horns or hoofs ; fr°® mto 35 potash; 2 to 4 iron; 3, 100 leather; 45 to 48 potash; and 2 to 4 iron,blood, 8 to 9 per cent, of the prussiate are obtained ; from horns, 9 to 10 ; and f r °leather, 5 to 6. The potash should he mixed in coarse particles, like peas, withcarbonized animal matter, which may be best done in a revolving pot, containing c tnon-balls. Of the animal coal and potash, equal parts may be taken, except with, 0 dfrom leather, which requires a few parts more potash per cent. On the average, h*and horn coal should afford, never less than 20 per cent, of prussiate, nor the leather t8; but by good treatment, they may he made to yield, the first 25, and the last fro®

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A patent for a singular process and apparatus, for making this compound, watained by a foreigner not named, by Mr. Berry, patent agent, in January, 1840.prescription is as follows

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Reduce charcoal into bits of the size of a walnut, soak them with a solution ^bonate of potash in urine ; and then pour over them a solution of nitrate or ace ^^es,iron; dry the whole by a moderate heat, and introduce them into the cast-ironpresently to be described. The following proportions of constituents have been ^to answer : Ordinary potash, 30 parts; nitre, 10 ; acetate of iron, 15 ; charcoal or45 to 55 ; dried blood, 50. The materials, mixed and dried, are put into ret ? r .“ s epa-lar to those for coal gas. The animal matter, however (the blood), is placedrate compartments of pipes connected with the above retorts. The pipes e< *. ntaI theanimal matter should be brought to a red heat before any fire is placed unretorts. ; Te four

In fig. 118, A, b, c, n, is a horizontal section of a furnace constructed to re ^gjateelliptical iron pipes. The furnace is arched in the part A, c, b, in order to re ^ tl» ethe heat, and drive it back on the pipes w, w', w", w'". These pipes are plac ^ j 0 heplane E, F, of the ellipsoid; a a, represents the grating or bars of tHe Ivirnaheated with coal or coke ; i, i, is the pot or retort shown in figs. 119, 120, i j c j, is aThis pot or retort is placed in a separate compartment, as seen in fig. H >