The volume on "Fractional Distillation" was written in the hope that it would be of assistance to chemists in overcoming the difficulties so frequently met with in the laboratory, not only in the actual carrying out of the fractional distillation of a complex mixture but also in the interpretation of the results obtained.

The last copy was sold shortly after the declaration of war, and the question then arose whether a revised second edition of the book in its original form should be published. It was thought, however, by the Publishers that it would be wiser to extend the scope of the work so as to include distillation on the large scale as carried out in the manufacture of important products.

That this change in the character of the book was really advisable became more and more evident as the war increased in intensity and magnitude, because of the immense importance of such materials as acetone, toluene, petrol, glycerine, and so on, the production of which involved processes of distillation on an enormous scale, and for some of which new sources or methods of formation had to be sought and investigated.

It was obvious that the larger book could only be of real value if the sections on manufacturing processes were written by chemists thoroughly conversant with the various subjects dealt with, and it was eventually decided that I should edit the book if I could secure the co-operation of experts in the different branches of manufacture.

In these preliminary negotiations I received most valuable assistance from my friends, Professor F. E. Francis, D.Sc, Ph.D., and Professor W. E. Adeney, D.Sc, and my sincere thanks are especially due to Professor Francis for the great interest he has taken in the production of the book.

Unfortunately the heavy pressure of work entailed on all chemists by the war caused serious delay in commencing the book, and progress has necessarily been slow.

The new work consists of seven sections, the first of which is practically a revision of "Fractional Distillation." In this section full reference is made to the valuable researches of Wade, Merriman, and Finnemore, of Rosanoff and his co-workers, and of Lecat; there is also an additional chapter on Sublimation.

The remaining sections, dealing with manufacturing processes, are as follows :

2. Distillation of Acetone and n-Butyl Alcohol on the Manufacturing Scale, by Joseph Reilly, M.A., D.Sc, F.R.C.Sc.I, F.I.C., Chemist-in-charge at the Royal Naval Factory, Holton Heath, Dorset, and the Hon. F. R. Henley, M.A., F.I.C.

3. Distillation of Alcohol on the Manufacturing Scale, by the Hon. F. R. Henley and Dr. Reilly.

4. Fractional Distillation as applied in the Petroleum Industry, by James Kewley, M.A., "F.I.C, Member of Council of the Institution of Petroleum Technologists.

5. Fractional Distillation in the Coal Tar Industry, by T. Howard Butler, Ph.D., M.Sc, F.I.C, Managing Director of William Butler & Co. (Bristol), Ltd., Tar, Rosin, and Petroleum Distillers.

6. The Distillation of Glycerine, by Lieut.-Col. E. Briggs, D.S.O., B.Sc, Technical Director, Broad Plain Soap Works, Bristol.

7. The Distillation of Essential Oils, by Thos. H. Durrans, M.Sc. (London), F.I.C, of Messrs. A. Boake Roberts & Co., Ltd., London.

S. Y. Dublin, August 1921.