Thermopile

“ The Thermocouple, or Thermopile, which depends on the production of a thermoelectric force when the junctions of different metals in an electric circuit are at different temperatures; and (2) the Electrical Resistance Thermometer, the action of which depends on the fact that the resistance of a pure metal to the passage of an electric current increases very considerably when the temperature is raised. ”

“ Heat is shown to be the nutriment of the electric current. When one face of a thermopile is warmed, the current produced, which is always from bismuth to antimony, is simply heat consumed and transmuted into electricity. ”

“ When a thermopile is used to observe radiant heat, it would be almost impossible to calculate on à priori grounds what is the value of each division of the galvanometer circle, and still more difficult to construct a galvanometer, so that each division should have a given value. But this is quite unnecessary, because by placing the thermopile before a body of known dimensions, at a known distance, with a known temperature and radiating power, we measure a known amount of radiant heat, and inversely measure the value of the indications of the thermopile. ”

“ But of these the capillaries seem first to acquire a renovation of their action, as the heat of the skin becomes first renewed, as well as increased beyond its natural quantity, and this in some parts sooner than in others; which quantity of heat is however not to be estimated simply by the rise of the mercury in the thermometer, but also by the quantity carried away into the atmosphere, or diffused amongst other bodies in a given time; as more heat passes through water, which boils vehemently, than when it boils gently, though the rise of the thermometer in both cases continues the same. ”

“ It cannot be well regulated without a thermometer, and 93° upon Fahrenheit’s scale is perhaps the best temperature. I have kept a patient in a bath of that heat for six hours, which he could not have endured for half an hour had the heat been three or four degrees higher.
The circumstance next in consequence, in the cure of this complaint, is the keeping up a moisture on the skin, and guarding the surface of the body from the access of the 536 air. This is particularly necessary with regard to the part itself, which should be constantly enveloped in warm, anodyne, and emollient applications. ”

“ The deductions to be drawn from the results obtained by abstracting heat from bodies are equally instructive. By taking advantage of the cooling produced by the rapid solution of salts of several kinds in water, an intense degree of coldness may be produced. [80] Indeed, the absorption of heat by liquefaction may be shown by the use of metallic bodies alone. If lead, tin, and bismuth, are melted together, and reduced to a coarse powder by being poured into water, and the alloy then dissolved in a large quantity of quicksilver, the thermometer will sink nearly 50 degrees. ”

“ The Doctrine of Latent Heat refers to such changes of consistence as we have just spoken of. It is to this effect; that during the conversion of solids into liquids, or of liquids into vapors, there is communicated to the body heat which is not indicated by the thermometer. The heat is absorbed, or becomes latent; and, on the other hand, on the condensation of the vapor to a liquid, or the liquid to a solid consistency, this heat is again given out and becomes sensible. ”

“ The tube is fastened to a thermometer by means of platinum wire, and then the bulb of the thermometer, with its attached tube, is immersed in strong sulphuric acid or paraffin, contained in a flask. The thermometer should be suspended midway in the liquid and heat carefully applied, so as to raise the temperature gradually and equably. It will be found that rapidly raising the heat gives a different melting-point to that which is obtained by slowly raising the heat. During the process careful watching is necessary: most substances change in hue before they actually melt. ”

“ The first purpose of heat is to sterilize completely the material so that no bacteria, germs, or spores may be left alive in the finished product. The second purpose of heating is to concentrate the material to a proper consistence and to thoroughly saturate all portions with sugar sirup. Incidentally, the heating also by the combined action of temperature and free acids in the fruit inverts a large quantity of the cane sugar that is used and thus prevents the finished product from granulating. ”

“ Thus, the chemical actions which result when ice and salt are mixed cause a withdrawal of heat, and a "freezing mixture" is formed. When a candle is burnt, the oxidation of its constituents, a chemical process, evolves heat. Oxidation is the great source of artificial heat, and animal heat is chiefly generated by the same process; in other words, animal heat is always the product of the chemical movements of the body, and these movements are almost exclusively of the character of oxidation. In the animal tissues a lessened oxidation is equivalent to a lessened heat-production, and vise versâ. ”

“ When the mixture of sulphuric acid and water is measured after it has cooled, it has no longer a bulk of two pints, but is found to have lost bulk equal to one or more ounces by measure. The heat evolved by a mixture of four parts of strong sulphuric acid and one part water is shown by the thermometer to be 300° Fahr., and this mode of obtaining heat has been used by aeronauts for the purpose of obtaining artificial warmth without the danger of setting fire to the gas in the balloon. ”

“ After the man enters, the lamp is removed and the water-current is so varied, if necessary, and the heating and cooling of the various parts so adjusted as to again secure temperature equilibrium of all parts. When the amount of heat brought away by the water-current exactly compensates that generated by the subject, when the thermal-junction elements in the walls indicate a 0 or very small deflection, when the resistance thermometers indicate a constant temperature of the air inside the chamber and the walls of the chamber, the experiment proper is ready to begin. ”

“ Artificial heat must be applied to the patient's body and extremities by means of hot water bags, bottles, bricks, plates, or any other handy device. Blankets should be put around the patient and every possible means resorted to, to maintain body heat. Mustard plasters may be put to the heart, spine and shins. Stimulants are necessary, such as hot black coffee if possible or hot water, in which a small portion of brandy may be put. If brandy is not obtainable the patient may take aromatic spirits of ammonia in hot water every twenty minutes for a number of doses. ”

“ The specification, after describing the use of a metallic coil of pipe, proceeds to add:--
'The melting-point of lead has been mentioned as the proper heat to be used in this operation, because it has been found to give good results. But the change of fatty matters into fat acid and glycerine takes place with some materials (such as palm-oil) at or below the melting-point of bismuth [510° Fah.] ; yet the heat has been carried considerably above the melting-point of lead without any apparent injury, and the decomposing action of the water becomes more powerful as the heat is increased. ”

“ An ordinary mercurial thermo-regulator may be used but it is preferable to employ a regulating capsule of the Hearson type (see p. 219) with a spring arm adjusted to the lever so that when the boiling-point of the capsule (e. g., 175°C.) is reached the gas supply is absolutely cut off and the jet cannot again be lighted until the spring-arm has been readjusted by hand. The thermo-regulator is by no means a necessity, and may be replaced by a large bore thermometer with a sliding platinum point, connected with an electric bell, which can be easily adjusted to ring at any given temperature. ”

“ Hair, wool, or feathers, do not possess an elevated temperature. This high temperature of the animal body, or, as it may be called, disengagement of heat, is uniformly, and under all circumstances, the result of the combination of a combustible substance with oxygen. In whatever way carbon may combine with oxygen, the act of combination cannot take place without the disengagement of heat. ”

“ For if the substance emitting heat without light, as iron below ignition, be placed in the focus of [Pg 138] a burning mirror, a thermometer in the focus of a similar mirror, placed parallel to it, though at a considerable distance, will be heated by it, and if a piece of ice be placed there, the mercury will fall.
Heat assists the solvent power of almost all menstrua; so that many substances will unite in a certain degree of heat, which will form no union at all without it, as dephlogisticated and inflammable air. ”

“ We, therefore, require our clothes to be absorbent, so that the evaporation shall not take place on the skin, but from the surface of the clothes, which prevents chill. The mere fact of covering impedes loss of heat by convection, and radiation, and provided our garments are made of non-conducting materials they necessarily minimize that loss of heat by conduction which is always going on between two bodies of different temperatures, such as the human body and the air, just on the same principle that a tea-cosy retains heat in the teapot. ”

“ The more acid the reaction, the less is the degree of heat that is required. The degree of heat required to destroy the germs of infectious diseases is believed to be greater than it is practicable to apply by the dry process to clothing and similar materials. The capacity of many of the organisms to reproduce may, indeed, be destroyed by a more moderate temperature, but a question remains concerning the germs or spores which had been taken up into the materials and were carried away with them. ”

“ Any certain temperature causes a given piece of metal to expand to a certain size, or to contract on cooling to a different size. Some thermostats are made of a straight rod of metal like copper which expands more than iron when heated. The rod is so placed that when cool it will allow fuel like gas or oil to pass thru a pipe, and when heated, it will expand enough to close the pipe, shutting off the fuel. They are placed so that they close the pipe at the temperature desired for an oven or supply of hot water. ”

“ Heat alone may result when it is transformed while in the circulating fluids, but partly heat and partly another force when it is transformed in some active tissue that has absorbed it; just as coal, though producing little else but heat as ordinarily burnt, has its heat partially transformed into mechanical motion if burnt in a steam-engine furnace. In such case the antithesis of Liebig would be reduced to this—that whereas nitrogenous substance is tissue-food both as material for building-up tissue and as material for its function ”

“ Soil scientists and other academics that sometimes seem to measure their stature on how well they can baffle the average person by using unfamiliar words for ordinary notions call these types of organisms thermophiles, a Latin word that simply means "heat lovers."
Compost piles can get remarkably hot. Since thermophilic microorganisms and fungi generate the very heat they require to accelerate their activities and as the ambient temperature increases generate even more heat, the ultimate temperature is reached when the pile gets so hot that even thermophilic organisms begin to die off. ”

“ The heat regulation is controlled by a thermostat of the same nature as in the form of incubator just described, but instead of operating by lowering or raising a cap over a main flue, so as to direct the heated gases either through the water tank if the temperature is falling, or through the main flue directly to the exterior if it is rising, it actuates a gas-governor, so that the flame itself is increased or diminished in size according to the needs of the incubator. ”

“ By friction, two pieces of ice may be made to melt each other; and could we, by mechanical pressure, force water into a solid state, an immense quantity of heat would be set free. By the condensation of hydrogen and oxygen gases, pulverulent platinum will become glowing red-hot, and, with certain precautions, even the compact metal, platinum, itself; the heat being derived from the gases, the union of which it has effected. A body passing from the solid to the fluid state absorbs heat from all surrounding substances, and hence a degree of cold is produced. ”

“ This heating may lead to “spontaneous combustion.” The high temperatures (60° to 70°) favor the growth of thermophil bacteria which cause a still further rise. The heat dries out the material, portions of which are in a state of very fine division due to the disintegrating action of the organisms. The hot, dry, finely divided material oxidizes so rapidly on contact with the air that it ignites.
A practical use of heat production by bacteria is in the making of “hot beds” for forcing vegetables (Fig. 74) .
ABSORPTION OF FREE NITROGEN. ”

“ In carrying out artificial refrigeration various kinds of machines are used for reducing temperature, in which the desired effect is produced either directly by the condensation and evaporation of suitable materials, such as liquid carbonic acid, ammonia, sulphurous acid, or indirectly by making saline solutions (calcium chloride) , cooled below the freezing point, circulate through a system of pipes fitted on the roof or walls of the space to be cooled. ”