Technikatörténeti szemle 19. (1992)

KÖNYVISMERTETÉS - Papers of the First „MINERALKONTOR” International Conference on the History of Chemistry and Chemical Industry (Veszprém, 12-16 August, 1991)

led ..Fudamentals of Chemistry", the author Karoly Nendtvich stopped following that line and returned to the use of Latin and Greek words. The language of ..Thermodynamics — as a whole — is a nice idiomatic Hungarian language which may seem somewhat strange to the reader of today because it avoids the use of foreign words. The following selected passages make use of the ..common" thermodynamic language. SELECTIONS 1. On the essence of heat „The heat can be approached as a subject or an object. As a subject it means the special feeling what we perceive with our body when moving closer to — e. g. — a hot stove or a burning object... The heat as an object is nothing but the reason for the above sensation... At the present state of natural science... the heat is not listed among the materials but it is declared as a vibration of ether (:aether:) being present world-wide having somewhat higher wavelength than what is necessary for the birth of daylight... we also consider the essence of heat as a vibratory motion..." 2. About the radiation of heat ..When the temperature of a body is higher than that of the surrounding ones, the propagation of heat in all directions can be observed from the fact that the temperature of those bodies is increasing. This propagation of heat happens generally in two ways, i. e. by radiation or by conduction ... from every hot body surrounded by a medium of the same kind, the heat is ..streaming out" in all directions by way of radiation. ... the heat... travels along in a straight line natural philosophers were not able to measure its rate of propagation yet, but based on the close relation between heat and light it is strongly suspected that it is the same or not much less than that of light... When heat rays originated from a hot body encounter a medium of different kind, they are — in part — reflected, transmitted, and absorbed. Under certain conditions the reflected and transmitted rays are subjected to a modification which is called polarization (:polarizatio:)... among the heat rays the same colour difference can be found (:Thermochromismus:) than that observed in the light beams... Heat rays passing through a heated body change their direction — i. e. suffer a refraction — according to the same laws"... that apply to light beams. ..Therefore, the invisible rays of heat can be focused by a lens made of a salt crystal just as the light beams are focused by a collecting lens." 3. About the thermal equilibrium The principle of the conservation of energy was established in the 1840's (Mayer, Joule, Helmholtz). This principle did not give a basis for the mainstream thought of the Jedlik manuscript yet. In spite of this fact, it gives a realistic wiew of thermal equUibrium in conformance with the energy conservation principle. „Since every body emits heat at any temperature, it is evident that bodies