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PREFACE.

WITH the exception of M. Ledoux' work on the properties of the various refrigerating agents published in 1879, Mechanical Refrigeration for some years possessed no literature of its own. More recently several works dealing with the subject have been published. Prominent amongst these is Professor J. E. Siebel's valuable book, which, though consisting largely of tables and formulæ, concisely covers the whole field. The other works, for the most part, confine themselves to a description of the various machines and processes by which Refrigeration is obtained. Up to the present no work has been published which deals comprehensively with the important questions of Insulation, Ice-making, and Cold Storage viewed more particularly from the standpoint of the owner and user. Consequently, when I was asked by the publishers to prepare this volume, I decided as far as possible to write from this point of view and to confine myself to the practical issues rather than to the purely technical. It may perhaps be thought that having this object in view I have devoted too much space to theory, but it seems to me that the very fact that Mechanical Refrigeration is a new and growing industry makes it particularly important that those people who contemplate employing it should know something of the theory which governs the practice. It is always better to be sure than sorry, and if the limits outside which it is

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neither wise nor profitable to venture are clearly understood, practice within those limits may be varied to any degree that the circumstances of any particular case may call for. Considerable misapprehension has existed regarding the behaviour of CO2 at temperatures near its critical point, and I have, with the valuable assistance of Mr Alfred W. Porter, B.Sc. (Fellow of, and Assistant-Professor of Physics in, University College), endeavoured to throw some light on the subject, making free use of the researches of Dr Mollier and the entropy diagram for the purpose. It may also be thought that I have passed over the Cold-Air, Sulphuric-Dioxide, and Ammonia-Absorption Machines too lightly; this, however, has been due, not to a want of appreciation on my part of their respective merits, but to the question of space. When writing on a comprehensive subject, one must either say something of little value about a lot of things or endeavour to say something of value about a few things. Rightly or wrongly, I believe that the subjects I have dealt with are the most important, and so I have confined myself to them.

The chapter on Auxiliary Plant will, I hope, be found useful. A cold store or ice factory is a carefully thought out combination of machinery and buildings, and very frequently I have found that though considerable attention has been paid to the efficiency of the refrigerating machinery, the auxiliary machinery and appliances have to a great extent been left to look after themselves. Economy in running depends very largely upon the efficiency of the auxiliary machinery, and it is just as worthy of consideration as anything else.

I wish it to be clearly understood, however, that I am not recommending the machinery and appliances, which I have described in this chapter and elsewhere, to the

exclusion of any other make. They are only to be regarded as good examples of their respective classes.

Part of Chapter XIV. has appeared in Cold Storage and Ice Trades Review; a portion of Chapter X. is reprinted from the Proceedings of the Cold Storage and Ice Association, and has appeared in The Engineer and other papers. A few of the blocks used in Chapter VII. have been borrowed from Central Station Electricity Supply, by Messrs Gay & Yeaman, to whom my thanks are due.

In conclusion, I desire to thank those friends who have so kindly given me assistance, as well as those firms who have so courteously given me drawings of their specialities. I also desire to record my indebtedness to the Technical Press, whose columns always contain so much valuable information.

60 QUEEN VICTORIA STREET, LONDON, E.C., April 1903.

HAL WILLIAMS.