Democratic Sentinel, Volume 6, Number 5, Rensselaer, Jasper County, 3 March 1882 — The Boiling-Point. [ARTICLE]

The Boiling-Point.

Dr. F. A. P. Barnard, who is a high authority, has contributed to Johnson's an interesting article on the boilingpoint, describing it as the temperature at which the elastic force of the vapor of any liquid is equal to the pressure of the atmosphere. When a vessel containing water is heated, the temperature rises and a vapor silently passes off from the surface ; but at 212 deg. F., or 100 deg. C. the barometric column standing at thirty iuches at the sea-level, steam begins to be formed in bursts at the bottom, and rising through the liquid, throws it into commotion. If the steam is allowed freely to escape, the temperature of the water rises no higher. The wa! er is then said to boil, and the temperature at which it remains is its boiling point. Every liquid has a boilingpoint of its own, which will be seen by the following table :

Deg- Deg. Liquid sulphurous Water 212.0 acid 17.6 Butyric ether .238.8 Aldehyde 71.8 Perchloride of tin 240.2 Ether 96.3 Terchloride of arCarbon bisulphido..llß.s senic 273.0 Acetone 133.3 Bromide of silicon ....308.0 Bromine 145.5 Terebeue 322.9 Wood spirit 151.3 Naphthalin 422.2 Ethylic alcohol 173.0 Sulphuric acid 620.0 Benzole 177.4 Mercury 662.0 The boiling-point of liquids is altered by various circumstances. Water, with common salt in it, requires greater heat to moke it boil than pure water. In a glass vessel the boiling-point is several degrees higher than in one of metal. But what most affects the boiling-point is variation of pressure. When the barometer stands at thirty inches, showing an atmospheric pressure of fifteen pounds on the square inch, the boilingpoint ol water is 212 degrees. When part of the pressure is removed, it boils before coming to 212 degrees, and when the pressure is increased the boilingpoint rises. Thus in elevated positions, where there is loss air above the liquid to press on it, the boiling-point is lower than at the level of the sea. An elevavfttion of 510 feet makes a diminution of one degree Fahrenheit; at higher levels the difference of elevation corresponding to a degree of temperature in the boiling point increases; and a method is thus furnished of measuring the height of mountains. At the city of Mexico, 7,471 feet above the level of the sea, water boils at 198.1 deg. ;at Quito, 9,541 feet, at 194 deg.; in the Himalayas, at the height of 18,000 feet, at 180 deg. Boiling water is thus not always equally hot, and in elevated places many substances cannot be cooked by boiling. Under the receiver of an air-pump water may be made to boil at the temperature of summer, and ether when colder than ice. By increasing the pressure water may be heated to any degree without boiling. There are one or two interesting experiments mentioned by Dr. Barnard. If a small quantity of water be poured iuto a silver basin heated above the boiling-point, but below redness, it will begin to boil violently, or perhaps burst into steam at once. But if the basin is heated to redness, the water will gather itself into a globule, and roll abont on the hot surface without coming to the boding point. It is remarkable that water which has been freed from air by long boiling has its boiling-point much raised ; and it has been known to reach 275 degrees Fahrenheit without boiling. —Chicago Inter-Ocem. “ Tib more brave to live than to die.” Therefore don’t wait till a slight Congh develops itself into consumption, bat secure a bottle of Dr. Bull's Cough Syrup at the small outlay of 25 cents, care your Cough and live on happily. Plating on the violin is claimed to cure nervousness.