Metal gradually cooled. Cakes separa ted from cast iron. Tempering of steel. caloric that are flying off, and those of the substance itself, which tend to anite. If this substance be a good conductor of heat, and the attractive power of its particles equal the expansive power of the caloric, it will return to its natural state without change of form. Such is a metal in fusion, which is left to cool gradually. If, under the saine circumstances, the caloric, rapidly absorbed, is separated in succeffive strata, this substance will separate into planes, which will be perpendicular to the direction the caloric takes to escape. Such is the case with cast iron in fusion, the surface of which is wetted to separate thin cakes from it: a cause analogous to what may have di vided basaltes into leaves, or thin strata, either perpendicular to the axes of the prisms, or around a globular mass. If, the motion of the caloric being uniform, the attraction of cohesion do not equal the expansile power, the particles of the substance will remain dilated; and then, if it be a good conductor of heat, they will maintain their situation without experiencing any division. Such is the effect of tempering steel, where the cohesive power of the particles of iron is broken by the interposition of carbon. But Quartz broken if the substance be not a good conductor of heat, it will to powder. fall to powder; as quartz strongly heated and immersed in water. The first of these circumstances has perhaps never occurred in volcanic productions, but the other must have been very frequent. Prismatic ditisions. To obtain prismatic divisions, let us suppose a basaltic mass still in its pasty state covering a considerable plain; and which, yielding to the laws of gravity, adheres strongly. to the base that supports it. Then, if the expansive force of the igneous or aqueous gasses happen to cease in consequence of their sudden or accelerated extrication, the particles, losing their fluid state, will tend to approach each other, yielding to the laws of gravitation, and also obeying the attraction of cohesion that they exert toward each other; and they cannot contract, but by following the diagonal direction resulting from these two powers. But the extent of this mass, its gravity, and the inequality of surfaces, opposing a general contraction like that which is experienced by by a cake of clay exposed to the fire on a support, there will necessarily be a vibration, and cracks that will determine spheres of attraction, round which the particles will agglomerate; and the centres will be so much more numerous, and the radii less, as the attractive force is more consider able, VI. Observations on the Oxigenized Muriatic Acid. By Mr. JOSEPH MOJON, Professor of Pharmaceutic Chemistry in the Medical School of the Imperial University of Genoa, &c.* the smell of IN N making oxigenized muriatic acid, I have several times Oximuri tie had occasion to observe, after having emptied the receiver, acid acquires into which I had distilled the acid, and left it a few hours ether: exposed to the light, that the little portion of acid, which commonly adheres to the inside of the receiver, lost entirely its peculiar suffocating smell, and acquired an aromatic odour perfectly analogous to that of muriatic ether. I re marked besides, that the oxigenized muriatic acid, though retained in bottles well stopped, and luted so that the gas cannot exhale, yet, if it remain some time exposed to the action of the sun, not only ceases to fume, but also acquires an ethereal smell, similar to that of muriatic alcohol or ether. without any This transmutation of oxigenized into simple muriatic changed into acid, without the excess of oxigen being able to escape, as muriatic acid also the ethereal smell it acquires by simple exposure to oxigen escap light, led me more than once to suspect, that the oxigen in ing. this case, instead of being extricated in the form of gas, entered into fresh combinations, and formed ether. To convince myself whether ether were really formed, I Ether obtained took a bottle filled with oxigenized muriatic acid, which from some. had been left exposed to light almost two years, and had * Annales de Chimie, Vol. LXIV. p. 264. VOL. XXIII.AUGUST, 1809. T acquired Farther expe mised. acquired the ethereal smell. I have mentioned, I saturated it with magnesia; and distilled the whole in a glass retort with a very gentle heat, till I had obtained a few ounces of a fluid, which I rectified afresh in a small retort over a lamp. This afforded me a perfectly limpid, colourless liquor, of a very penetrating ethereal smell, and a taste resembling that of muriatic ether diluted with water. It did not change the colour of infusion of mallow flowers; and it did not take fire at the flame of a candle, being still very dilute. The small quantity of liquor obtained by this process not riments pro- allowing me to proceed to a fresh rectification, to deprive it entirely of the superabundant water it contained, I mean to make new trials with a larger quantity of acid. Perhaps ether formed in the distillation, From the observations I have thus briefly given, and which no doubt deserve to be repeated and confirmed by farther experiments, I am far from pretending to explain by vague hypotheses the formation of acohol, or of ether, by oximuriatic acid, and to point out whence it derives its component parts. We may suppose, however, that a portion of ether is formed at the time of distilling the oximuriatic acid, and that the potent and suffocating smell of this acid prevents that of the ether from being perceived. In fact the celebrated Giobert of Turin, in distilling oximuriatic acid sixteen years ago, observed a volatile oil similar to that which Mr. Westrumb had discovered some time before him. Mr. Giobert tells us, that this oil is of a yellowish as oleum vini brown colour, very clear, and analogous to the oleum vini ; found to be. but that it is difficult to determine its precise quantity, since when once separated it dissolves anew very readily in the aqueous vapours, that fall into the receiver. This chemist imagined he might estimate the quantity of oil obtained from a mixture of a pound of sulphuric acid with eighteen ounces of muriate of soda at 30 or 35 grains. VII. Extract of a Letter from Mr. RESAL, Apothecary at Remirement, to Mr. CADET, Apothecary to the Emperor, on the Conversion of Malt Spirit into Vinegar, and on the Red Colour of Oil of Hempseed *. I vinegar. TAKE the liberty of imparting to you an observation Malt spirit respecting the article of Mr. Hebert of Berlin, whose pro- converted into cess you could not verify without it. I communicated it to Mr. Parmentier a twelvemonth ago, with several other notes, part of which was inserted in the month of May, 1806. One of these was on the vinegar of brandy, which chance threw in my way. I had mixed some malt spirit (alcool de bierre) with an equal quantity of water, and added to it some beech charcoal. Being set aside and forgotten, I was surprised at the end of a twelvemonth to find it converted into a very strong vinegar, and the unpleasant taste of the beer still subsisting. With your permission I will add an observation respecting the property of liquids to absorb different solar rays. It is known, that various substances absorb this or that Oil of hempluminous ray, but I do not believe that any one has menseed grows red in the sun. tioned the property, that oil of hempseed, cannabis sativa L., has to absorb the red rays when they are direct only, and to appear of a fine blood-red colour; so that, being lighter than rape or linseed oil, as it returns to the upper part of the vessel it appears equally red, without changing the colour of the oil it floats on. Its use in the arts, since it offers more resistance to the air than linseed oil, and does not skin [ne se crispe pas] like it; and its mixture with oils for the lamp being very common from its low price, while it yields a thick smoke; require a method of detecting it. This that I have mentioned perhaps would answer, and even show the effect of the solar rays on different sub stances. * Annales de Chimie, vol. LXIV, p. 261. T 2 Remarks VIII. gitude in the Gulf of Flo rida. Remarks on some Points of Hydrography, by Mr. LEBLANC, Errour of lon- THE gulf of Florida, or new Bahama Channel, is greatly frequented by ships of all nations, that trade to or cruise in the Gulf of Mexico; yet the latitudes and longitudes of the principal points in it have not been fixed. They are not mentioned in the Tables inserted in our Connoissance des Temps, or in the English collection entitled "Tables requisite &c." Accordingly we are obliged to have recourse to the most modern charts. French navigators use the General Chart of the Atlantic Ocean published in 1791, and revised and corrected in 1792. I think I can show, that there exists an errour in longitude of 52′ with respect to all the points of the gulf. I was led to notice this on the following corrected. Old Bahama channel. occasion. On the 25th of January, 1807, in the afternoon, on board the Foudroyant, we saw waves and breakers on the North of the Great Bahama. At 4 o'clock we set, at a small distance, Lena Key N 80° E, and that of Azena N 45° E by compass. The longitude given by our time-keepers No. 40 and 76, reduced to that hour, was only 80° 17′ 30′′, while that by the chart was nearly 82° 15'. Whence it follows, that the whole course of the gulf is too far west about 52′ of a degree †, a considerable errour in those latitudes. The going and state of the two timekeepers had been carefully observed during our long stay at the Havannah. Their errours were almost nothing after we had been at sea eight days, when we had soundings abreast of Cape Henry. The results given by the observations taken with the reflecting circle gave us no reason to suspect any thing incorrect in the longitudes: and when we entered Brest the absolute errour of No. 40 was only 7 of a degree after a voyage of thirty-five days. Green Key is one of the principal marks of the Old Ba* Journal de Physique, vol. LXV, p. 55. I give the difference as in the original, not knowing where the errour is hama |