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known. The people are said to have been very savage and bar-barous; living upon raw flesh, and drinking the blood of horses attheir feasts, according to Stella, even to intoxication. Nay, soextremely savage were this people, that they were even unac-quainted with the method of constructing huts, and took up theirdwelling in caves and cavities of rocks and trees, where they pro-tected themselves and children from the inclemencies of the wea-ther. 'The air of Prussia is cold but wholesome, and the soil fruit-ful in grain ; affording, besides, plenty of pitcoal and other fuel.The rivers and lakes are well stored with fish ; and amber is foundon its coast towards the Baltic. The principal rivers are the Vis-tula, Pregel, Memel, the Passarage, and the Elbe ; all of whichfrequently do damage by their inundations. Frederic the Great,King of Prussia, by the assistance of an excellent police, broughtthe commerce and manufactures of this country to a very flourishingstate, which during his life were daily improving. The manufac-tures of Prussia consist in glass, iron-work, paper, gunpowder,copper, and brass mills : manufactures of cloth, camblet, linen,silk, gold and silver lace, stockings, and other articles. The in-habitants export variety of naval stores ; amber, linseed, and hemp-seed, oatmeal, fish, mead, tallow', and caviar ; and it is said that500 ships are loaded with those commodities even' year, chieflyfrom Koningsberg . The King of Prussia is absolute through allhis dominions ; but Frederic II . was too wise to oppress his sub-jects, though he availed himself to the full of his power. The go-vernment is by a regency of four chancellors of state, viz. 1. Thegreat master. 2. The great burgvave. 3. The great chancellor;and, 4. The great marshal. There are also some other councils,and 37 bailiwicks. The state consists, 1. Of counsellors of state.2. Of deputies from the nobility; and, 3. From the commons.Besides these institutions, the late king erected a board for com-merce and navigation. The military regulations introduced byFrederic the Great, had a wonderfully quick operation in forminghis troops and recruiting his armies. Every regiment has a parti-cular district assigned it, where the young men proper for bearingarms are registered ; and when occasion offers, they join their re-giment, and being incorporated with veterans, they soon becomewell disciplined troops. The Prussian army, in time of peace,consists of 175,000 ot tile best disciplined troops in the world ;and during the last war, that force was augmented to 300,000 men.The manners of the people diifer but little from those of the Ger-mans . The established religions are those of Luther and Calvin,but chiefly the former ; though almost all other sects are tolerat-ed. Prussia abounds with flocks and very line horses; also elks,deer, stags, roebucks, hares,and other small game: it is also infestedwith bears,wild boars, lynxes,wolves, foxes, &c. The coasts aboundwith salmon, sturgeon, cod, turbots, soles, halibuts, pikes, perches,plaise, &c. The King of Prussia, by means of the happy situa-tion of his country, its inland navigation, and the excellent regu- 'iations of his predecessors, derives an amazing revenue from Ibis'country, which about a century and a half ago, was the seat ofboors and barbarism. It is said, that amber alone brings him in2b,000 dollars annually. Ills other revenues arise from his de-mesnes, his duties of customs and tolls, and the subsidies yearlygranted by the several states ; but the exact sum is not known.The royal arms of Prussia are argent, an eagle displayed sable,crowned, or, for Prussia; azuro, the imperial sceptre, or, forCourland ; argent, an eagle displayed, gules, with semicircularwreaths, for the marquisate of Brandenburg: to these are addedthe respective arms of the several provinces subject to the Prus-sian crown. This country was overrun by the French in 1 BOG and 1807, in consequence of which the Prussians have beenobliged to abandon all their Polish dominions; so that this king-dom is now reduced into the state in which it was in before the1st of January, 1772.

PRUSSIAN BLUE , a rich pigment prepared by dryingblood, and mixing three parts of the dried residuum with two partsof the potass of commerce, and calcining the mixture in a cru-cible by a red heat.- it is then boiled in successive portions of water,which are afterwards mixed together, anti concentrated by evapo-ration, A solution is prepared of one part of sulphate of iron, andtwo parts of alum, and to this the liquor obtained from the cal-cined blood and alkali is added, as long as any precipitate isformed.' (I his precipitate is of a green colour, but by washingit with a little dilute muriatic acid, it becomes of a dark rich bluecolour. This forms the Prussian blue of commerce.

PRUSSIA'TES, salts formed by the union of the Prussic acidwith different bases. See Chemistry. Prussiatcs have scarcelyany permanency, unless they be united with a little of some me-tallic oxide, and therefore in the state of triple salts; and hencethey have not been much examined. Mere exposure (o the air,or to a heat of 120°, is sufficient to decompose them. The tripleprussiates, not being liable to spontaneous decomposition, havebeen employed with success, as chemical reagents, and have ex-cited a good deal of interest, in consequence of the important pur-poses to which they may be applied.

Prussiate of Ammonia, lias the odour of pure ammonia:when heated, it evaporates completely.

Prussiate of Ammonia and Iron . This triple salt has beenemployed as a test, but it is not easy to obtain it in a state of pu-rity. It was discovered by Macquer , and first recommended byMeyer, ft. forms flat hexangular crystals soluble in water, anddeliquesces in air. Ileal decomposes it.

Prussiate of Fixed Alkalies. These salts, formed by dis-solving tlie fixed alkalies in Prussic acid, are very soluble in water,tinge vegetable blues green, and are partly decomposed by a mo-derate heat.

Prussiate of Iron. The prussiates of iron enter as ingredi-ents into the triple salts formed by the Prussic acid. There are nofewer than four prussiates of iron.

Prussiate of Iron, Blue, or the Prussian Blue , is com-posed of Prussic acid and brown oxide of iron. It is a deep bluepowder, insoluble in water, and scarcely soluble in acids. SeePrussian Blue .

Prussiate of Potass and Iron . This salt, known also bythe names of Prussian alkali, Prussian test, triple prussiate of pot-ass, &c. has been chosen by chemists as the best combination ofPrussic acid, for detecting the presence of metals, and more espe-cially for detecting the existence of iron. To chemists and mine-ralogists it is one of the most important instruments ever invented ;as, when properly prepared, it is capable of indicating whetherany metallic substance (platinum excepted) be present in any so-lution whatever, and even of pointing out the particular metal,and ascertaining its quantity. This it does by precipitating themetals from their solution, in consequence of the insoluble com-pound which it forms with them. And the colour of the precipi-tate indicates the particular metal, while its quantity enables us tojudge of the proportion of metallic oxide contained in any solu-tion. See the next article.

PRUSSIC ACID. “ The Prussic acid (says Dr. Thomson,Syst. of Chem. II. p. 157 ,) is one of the most important instru-ments which the chemist possesses, and lias perhaps occupiedmore of the attention of the most distinguished cultivators ot thescience; than any other acid.” tt was discovered about a centuryago by Diesbach at Berlin ; and a method cf preparing it waspublished by Woodward in the Philosophical Transactions for1724 , which he said he had got from one of his friends in Ger-many . After various attempts to ascertain the nature and com-ponent parts of this acid Scheele at length succeeded and explain-ed its properties and composition. lie observed that the Prus-sian alkali, after being exposed for some time to the air, lost thoproperty of forming Prussian blue ; the colouring matter musttherefore have left it. lie put a small quantity of it into a largeglass-globe, corked it up, and kept it some time ; but no chargewas produced either in the air or the Prussian alkali. Something-must therefore displace the colouring matter when the alkali is.exposed to the open air,which is not present in a glass-vessel. Was itcarbonic acid gas ? To ascertain this he put a quantity of Prussianalkali into a glass-globe filled with that gas, arid in twenty-fourhours the alkali was incapable of producing Prussian blue . It istherefore carbonic acid gas which displaces the colouring matter.He repeated this experiment with this diiterence, that he hung inthe globe a bit of paper which had been previously clipped into asolution of sulphate of iron, and on which he had let fall two dropsof an alkaline lixivium in order to precipitate the iron. This pa-per was taken out in two hours, and became covered with a lineblue on adding a little muriatic acid. Carbonic acid, then, hasthe property of separating the colouring matter from alkali withoutdecomposing it. He found also that other acids produce the same.effect. Hence he concluded, that the colouring matter, might beobtained in a separate state. Accordingly he made a great manyattempts to procure it in that state, and at last discovered the fol-

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