SCIENCE. FOR THE PORT FOLIO. "Or with fine films, suspended o'er the deep, THE Succeeding subject occupied the attention of Dr. Franklin, and other philosophers, some years ago; their theories did not prove satisfactorily to themselves; and therefore, were actuated to abandon the subject, without deriving much information from their philosophic industry. Since great men have been unsuccessful, it is not necessary the subject should be disregarded; for what may have resulted unsuccessfully in one person's hands, may prove happily in another's. It is a well known fact among many persons, that oil produces a calmness of the waves at sea, when poured upon them during their commotion. How the oil acts in producing this phenomenon is the purport of this theme. The wind is generally the efficient cause of the waves: therefore, it is evident, that whatever removes this cause, must act by preserving its uniform attraction of cohesion, and glide off the wind by its lubricity. "Oil and water reciprocally repel each other:" therefore they will not combine; the oleaceous particles wonderfully attract each other, and firmly preserve their cohesion. This has been ocularly demonstrated to many scientific and illiterate persons at sea. When oil is poured into the sea, it expands in a very surprising manner, covers a greater space than any known fluid of the same quantity. It may better be explained by comparing the oil, when expanded, to a sheet of paper placed upon the surface of the water, to intercept the wind, provided the paper do not imbibe water, for if this be the case, the paper will probably sink-however, the composition of the paper admits the passage of water, whereas that of the oil does not, it being specifically lighter than water, and many other fluids, always remains on the superficies of the water: the wind acting on this paper cannot incommode the water, consequently, when the wind is intercepted by the paper, the waves will subside and cease to rise as long as the wind is removed: such is the manner oil calms the waves at sea, by its lubricity and firm preservation of its attraction of cohesion. To evince this fact in a clearer manner, let some oil be poured into a body of water, during a windy day, and the spectators may be satisfied as to the cause of the subsidence of the waves. Oil cannot prevent any other moving power from acting upon it, than that of very subtle fluids. The sea being covered for a considerable space with oil, the particles of which preserving their attractive quality, and continuing firmly cohered together, will be the rampart upon which the wind will have no influence; for the waves being subsided can no longer rise, since their cause is prevented. To conclude, it is requisite to call the attention of the ingenious reader, to peruse with care and eagerness, for the acquirement of truth, the before discussion, and no doubt but he will not swerve much in opinion from the writer. SIR, CORRESPONDENCE.-FOR THE PORT FOLIO. ERUPTION OF THE NEW VOLCANO NEAR ST. MICHAELS. OBSERVING a few days since, in one of our daily papers, an account related by our minister at St. Michaels of the eruption of a new volcano, which lately appeared near that place, attended with a circumstance somewhat extraordinary in its nature, for which no probable reason was assigned; I have been induced to transmit to you the ensuing explanation, which seems to myself, satisfactorily to account for the circumstance above alluded to; namely: the passage of flame through the body of water, and issuing above the surface. As some of your readers may, perhaps, not have seen the account of the fact, I shall here transcribe it for you. It is contained in a letter from Thos. Hickling, vice-consul of the U. S. for the island of St. Michaels, to John B. Dabney, consul of the U. S. for the Azores. DEAR SIR, St. Michaels, February 28th, 1811. On the 29th, 30th, and 31st ult. we were much alarmed by frequent shocks of earthquakes, perhaps upwards of twenty; and on the first instant, information was received here, that a volcano had broken out in the sea, five leagues west of this port, and half a league from the land, in fifty or sixty, and some fishermen say, in seventy to eighty fathoms of water. I repaired immediately to that part of the island, and, to my utter astonishment, saw a vast column of black smoke issuing out of the ocean. The wind was a gale from the southward and blew the smoke over the land. The sea was excessively agitated, and the surf on the shore was frightful. I was assured by the peasants, that on the preceding night fire had been emitted; and being curious to ascertain that fact, I returned to the city and desired my son and son-in-law to go and remain opposite the volcano all night. They did so, and saw at various times during the night, fire issue forth like a number of rockets discharged together. Large masses of stone or lava were continually thrown above the surface of the sea. Wonderful indeed how fire could pierce such a vast body of water; yet such was actually the case. In eight days it entirely subsided, leaving a shoál on which the sea breaks. What a happy deliverance for us; for had this formidable volcano opened on the land, it would probably have gone near to ruin this island. I am, &c. &c. T. H. + It is a consequence always attending eruptions of this kind, that immense quantities of hydrogen gas are produced, which of all substances in nature is the most inflammable. Now suppose the ground to have been about fifty or sixty fathoms (which, however, is not of much importance) below the surface of the water; also that an immense body of hydrogen has risen from the crater. Imagine this volume of gas having become very much condensed by the surrounding water, and also excessively heated from the fire below; and ascending to the surface of the sea in consequence of its inferior specific gravity; as soon as it comes in contact with the oxygen of the atmosphere, it will explode, and impel the water around violently, at the same time flame will issue above. This effect may be accounted for in another way. We might suppose a large quantity of hydrogen to be formed within the crater of the volcano; and also a portion of its auxiliary principle, oxygen; which being combined, as they are specifically rising, and fired by the intense heat below, will explode. Now we |