G. B. Seely

“ In producing cold we therefore seem but to assist Nature to restablish, in an infinitesimal degree, the state of comparative molecular inactivity that distinguishes cold from heat, and which characterizes the vacuum. ”

“ Since the experiments of Professor Twining thirty years ago, with sulphuric ether, the problem of producing artificial cold has been attacked by many, but the basis of the more important and successful systems employed has been, as in Twining's experiments, the volatilization of a liquid in vacuo, by means of a gas-pump. Of the various substances available in nature for this purpose, ether and ammonia have received the most attention. ”

“ While the progenitors of the race seem early to have discovered the means of producing heat artificially, for their rude arts and for their bodily comfort, it is not probable that the means of obtaining artificial cold could ever have seemed to primitive man a pressing need. ”

“ Not alone in warm countries is ice rapidly becoming a universal necessity, but, in myriad industries in temperate climes, the economy experienced by using air-cooling contrivances in the place of Nature's unwieldy, slippery, and not always obtainable product, has long since been satisfactorily demonstrated by the widespread use of various systems of machines. ”

“ A double-acting vacuum-pump volatilizes the agent in the refrigerator coils, and this is attended with the development of an intense cold, which is communicated to the surrounding mixture, and the latter, by means of a circulating pump, is made to flow through a suitable tank containing vessels of water to be frozen, or, if air-cooling only be desired, through iron tubing placed along the walls or ceiling of the chamber to be cooled. ”

“ In these days of rapid development of the mechanic arts, it seems hazardous to assert impossibility of any mechanical problem involving the substantial amelioration of man's condition. The manifest need of an improvement seems to be but the condition of its realization and development; sooner or later appears the embryo invention destined to be the theme of long study and continual modification, the perfected product often bearing little or no resemblance to the crude prototype that may have first embodied an idea fraught with lasting good to man. ”

“ The object sought has been the most economical method of employing those substances that are capable of producing the greatest degree of cold. But a difficulty is encountered in the high pressures of the gases produced in the pump, as there is no evading the physical fact that the cold-producing power of a gas is a concomitant of its tension, or pressure varying directly therewith. ”

“ Thus, ammonia, with a pressure at rest of eight atmospheres, and at work of twelve to twenty atmospheres according to the temperature, is an excellent refrigerant, but the use of a gas with such a high pressure is attended with obvious drawbacks. At the other end of the scale is ether, which is manageable at a low pressure, viz., zero at rest, and ten to fifteen pounds per square inch at work ”

“ In one sense heat seems to be but an incident of the cosmic order, an exception to a state of things pervading interstellar space, and toward which the warm earth, and her sister planets, and all the burning orbs of heaven, are gradually tending. ”

“ In other words, the ether is found to have accomplished the greater part of the work, and a law of nature governing the action of certain chemicals in combination is availed of to reduce the mechanical labor of liquefaction to a minimum. ”

“ There are certain general features common to all the systems employing a liquid volatilizable in the vacuum-pump, but the peculiar features of the binary absorption process admit of such a simplifying of the mechanical appliances employed as to materially distinguish their construction from that of other systems. ”

“ The ether, by absorbing the gas of the other constituent liquid, reduces the mechanical problem to that of liquefying a gas having a pressure not approximating that of sulphurous acid, viz., fifty to eighty pounds or more per square inch, but barely more than that of ether itself, viz., twenty pounds. The pressure of the compound at rest, like that of ether, is nil. ”