โ Scribed by R.H.O.
No coin nor oath required. For personal study only.
on this subject. After explaining how the conception of the absolute zero, as the temperature at which interchangeable heat motion ceased, although a minimum quivering motion of the molecules still remained, had been reached, he dealt with the methods by which gases had been liquefied and then referred to a new method of cooling substances which, he said, had been introduced during the last few years. This depended upon a curious magnetic effect. In the Clarendon Laboratory to obtain the lowest temperatures by this means, a piece of alum was cooled in liquid helium to a temperature of about I deg. abs., a magnetic field then being applied and heat evolved. As, however, the alum was left in thermal contact with the liquid helium, the heat was carried off and the whole system cooled to about I deg. abs. The helium gas which made the thermal contact between the alum and the outer bath of liquid helium was then pumped off so as to insulate the Mum, as far as possible, from external surroundings. Then, on the removal of the field, the temperature would fall and in this way substances could be cooled below o.oI deg. absolute. The object in cooling to these low temperatures was to measure the characteristics and properties of substances in this region. One of the phenomena investigated was the fall in the specific heats of solids which led to results exactly in accord with the quantum theory, and actually first caused scientists to realize that the Quantum Rules were absolutely general and not confined to the transfer of radiation to and from matter. With regard to the direct applications of low temperature research in industry the lecturer said he had no doubt that in, say, 15 years time, liquid hydrogen would be just as much an article of commerce as liquid air now is. R. H. O.
๐ SIMILAR VOLUMES
A general discussion is given of a method used to determine lubrication requirements for diesel engines. It shows how laboratory experience is gained in single cylinder and multicylinder engines. Field experience is obtained from both proving ground and user tests before lubrication recommendations