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and, for the purpose of making a sonorous swell, ap. plied the shield to their mouths. These sentences, or cries, were supposed to strike terror on the enemy, and to incite their own troops to valour. A great number of different cries were in use amongst them. “ Deus adjura”, and “ Deus vult” were the famous cries of those enthusiastic adventurer, who engaged in the wonderful and calamitous expeditions called the Crusades. “ Dieu et les Dames” was the cry of the Knights, whose gallantry led them to the most desperate feats of agility and courage, to win the applauses of their favourite females, and be considered as the avengers of injured innocence. The cry of every Banneret was engraved on his shield, as emblematic of his valour, his good qualities, or those of his progenitors; and they have ever since been continued in the complicated system of Heraldry.

The word Motto is derived from the Greek Mulos, a short quotation.

QUERY 49. Answered by Mr. J. Baines, jun. Air bubbles are formed by a thin covering of water inclosing a quantity of air. The air presses upwards and the water downwards, and form a spherical surface, the pressure of the water being equally diffused and equally distant from the centre of the sphere; because all bodies, when in a fluid state, invariably assume that form, by the great power of attraction which the Creator has stamped on all matter in the universe. If air bubbles are not perfect spheres, it is because the lower segment, by being immersed in the water, is either destroyed or imperceptible, "Mr. Bamford's solution was similar in substance.

Mr. M. Harrison observes, “ If water or any other fluid be greatly agitated, atmospheric air is driven into it; and the specific gravity of air being above 800 times lighter than water, the air rises to the surface, and buoys up a few particles of the fluid; and being cased round by these particles, it forms bubbles, which for a small time assume the form of the upper segment of a sphere, until the elasticity of the air so confined bursts them.”

Mr. A. Hirst says, “ when an air bubble is formed, it assumes a spherical shape on account of the attraction of the particles of the fluid, a sphere being the most capacious of any solid of the same surface; and it is proved in the solution to Quest. 46, p. 226, Vol. II. Enquirer, that the most capacious segment of a sphere with the same curve surface, is, when the height is three-fourths of the diameter; which form, in air bubbles, is not uncommon, abstracting a little for the weight of the fluid composing the bubble, which will necessarily make the height something less than threefourths of the whole diameter." Mr. J. E. Savage also sent a solution.

Query 50.

Answered by Mr. A. Hirsi. Iron, after having been rendered soft by heating, will, in length of time, become very hard again, by being exposed to the atmosphere, and the time required to harden it will be in proportion to the size of its particles; that is, a small piece of iron sooner becomes hard again than a larger one; and it is most probable, from the query, that this is the case with brass, though not in so great a degree; for if brass be heated, it is rendered softer, whether it be suddenly quenched or not, but the less so, if it be suddenly quenched; which strengthens the above conjecture.

Mr. J. E. Savage says, “ It is obvious that the brass filings will take a longer time to melt than the same weight in a lump; because the caloric will escape from the filings, but in the lump it cannot, neither can the air act so freely within it.”

Mr. John Smith observes, that “the fusion of metals is accomplished by the action of caloric, which, by combining with the solid substances, diminishes or des stroys the attractive force of their particles, and causes them to pass into the fluid state. Now it is well known that solid metal is more permeable to caloric, or, in other words, is a better conductor of heat than filings are; it will, consequently, fuse with greater facility."

Mr. Bamford and Mr. Baines expressed similar opinions.

Mr. R. T. jun. says, “ I suppose that brass in lump will fuse in less time than the same in filings; for this reason, caloric is able to pervade all bodies, and in proportion as bodies are good or bad conductors of electricity, are they good or bad conductors of caloric; and the more light and porous a body is, the worse conductor it is. Now brass filings occupy a greater space than brass in lump; of course, the interstices of the filings are occupied by atmospheric air, which is a worse conductor of caloric than metals are, of course prevents it from so soon coming into fusion. Also, matter of every description is regulated by attraction and repulsion, and fluidity is supposed to be an altera. tion in the situation of the particles of a body; now in the filings, the caloric requires a longer time to exert its repulsive force, to overcome the cohesive attraction of the metal; and this is, in my opinion, the answer to the query.

Mr. John Nowell *, of Farnley Wood, near Huddersfield, refers to the Theory which he proposed in his solution to the 32d Query (see p. 195, Vol. II. Enquirer) for an answer to this query.

QUERY 51. Mr. M. Phoston gives the two following methods, extracted from the Monthly Magazine, Vol. XXXIII. p. 426 :

A Process for purifying Fish Oil.—Take one gallon of crude stinking oil, and put to it a pint of water, poured off from two ounces of lime slacked in the air; stir the mixture up several times for the first twentyfour hours; then let it stand a day, and the lime-water will sink below the oil, which must be carefully separated from it.

Another Method for purifying it more completely. Take one gallon of crude stinking oil, and mix with it a

.* This ingenious Gentleman informs us, that after a series of laborious experiments, he has at length decomposed the muriatic acid. The result of his experiments will shortly be laid before the public. Ed.

quarter of an ounce of powdered chalk, a quarter of an ounce of lime slacked in the air, and half a pint of water; stir them together, and when they have stood some hours, add a pint of water and two ounces of pearl ashes, and place the mixture over a fire that will fust keep it simmering, till the oil appears of a light amber colour, and has lost all smell, except a 'hot, greasy, soap-like scent: then superadd half a pint of water, in which one ounce of salt has been dissolved, and having boiled it half an hour, pour the mixture into a proper vessel, and let it stand for some days, till the oil and water separate. If this operation be repeated several times, diminishing each time the quan. tity of ingredients one-half, the oil may be brought to a very light colour, and rendered equally sweet with the common spermaceti oil. · Oil purified in this manner, is found to burn much better, and to answer much better the purposes of the woollen manufacture. If oil be wanted thicker and more unctuous, it may be rendered so by the addition of tallow or fat.

Mr. Jos. Bamford communicated a method similar to the above; and adds, a patent was granted in 1799 to Mr. Collier, for a chemical process for freeing fish. oils from their impurities of smell, taste, and colour; which process was as follows:-Pour a quantity of fish-oil into a vessel which is heated to the temperature of 110 or 120 degrees of Fahrenheit's thermometer, when a portion of caustic mineral alkali is added, the weight of which is equal to four parts to the hundred of the oil. The mixture is next agitated, and after the sediment and salt have subsided, it is drawn off into another vessel, containing a sufficient quantity of finely pulverized fresh-burnt charcoal, and a small proportion of diluted sulphuric acid; the agitation is repeated, and when the coal, together with the saline and aqueous particles, have subsided, the 'oil is passed through certain strainers, and thus rendered perfectly transparent and fit for use. (For a more particular de. scription see 10th vol, of the Repertory of Arts, &c.)

QUERY 52. : Answered by Mr. John Nowell (the Proposer)..

Prussic acid holds potash or soda in a state of com. bination in a very feeble degree; even the weakest of acids, the carbonic, is capable of decomposing these salts, and forming a carbonate with their respective bases. There is a triple salt of prussic acid, potash, and iron, much used as a test, and long since known by the name of Prussian alkali : this substance precipitates all the oxides of iron in coloured precipitates, depening on the degree of oxidation, and is still capable of holding a limited portion of the same oxidein solution. A very curious fact; to attempt to explain the rationale would ill become me, as it resisted the sagacity of so eminent a chemist as M. Proust. If from this trinary combination, or as it is called the triple prussiate of potash and iron, we could take the iron contained in a state of dissolution, its fixity and utility as a re-agent would be destroyed, and the carbonic acid of the atmosphere would in a certain degree decompose the salt if the bottle was not well corked, drive off the acid, and combine with the base. Hence the prone. ness of the simple prussiate to decomposition : but if potash holds the prussic acid with a weak affinity, the case is not so with iron; it holds it with a strong one, and in fact is capable of taking it from its strongest combinations. Upon this datum we may frame a theory, which will account for the fact expressed in the query. We will suppose the triple prussiate made up of atoms arranged with particular symmetry; one atom of the salt we will suppose is prussic acid, another potash, and a third iron : now the attraction of the iron will be extended when so minutely divided, even past the sphere of action of the potash; and if, by combination of the base with carbonic acid, thé prussic acid of the triple prussiate had a tendency to fly off, the superior attraction of the iron would hold it and check its flight.

J. H. N. near Leeds, says, “ though the prussic acid may unite with alkalies, it is in so inconsiderable a

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