The blast-furnace is the key which unlocks Nature's stores of iron for our use. It is unique in having been unchanged in principle for several centuries, and in having no substitute. For the steam engine we have the gas engine, for the Bessemer converter the open-hearth, but if the blast-furnace were taken from us, civilization would be halted.

It is the most complex in principle and the most difficult to operate successfully of any metallurgical apparatus, and its proper understanding probably requires more years of study than any other industrial operation; for all these reasons it deserves the profoundest investigation and consideration.

It is surprising that in nearly half a century, since the publication of Sir Lothian Bell's last work, no comprehensive book on this subject has appeared in any language, and a growing need has been felt for one.

I happen to have made several investigations which served to explain some of the phenomena of the blast-furnace not previously understood, and it seemed proper that the results should be recorded, for if they are right, they will save others the time and trouble of going over the same ground again, and if they are wrong, they will inspire the oncoming generation to prove them so, and in the end will, even by that circuitous route, lead to the truth at last. This is my reason and must be my apology, if any be needed, for attempting to treat a subject of such magnitude and difficulty. The best efforts of my leisure for more than three years have been spent upon the work, but the subject is too vast for one man to do it justice.

In many cases my own opinions are given for what they may be worth, because it seems to me that those books which simply give a number of opinions without any indication of the author's preference are of little real use. Nevertheless, I have tried to distinguish clearly between proven facts and my own opinions; for this reason I have used the first person throughout.

The book is deficient as regards the history of its subject, for the reason that I know little about the early history of the blast-furnace and have but little faculty for historical investigation. I have attempted to give enough recent history to show the present trends in the industry, and to make a presentation, not of an industry in a static condition, but of one undergoing a healthy evolution.

It will be noted that, as the title implies, the book contains little or nothing on foreign blast-furnaces; this is not because these are unworthy of attention, but because my very limited knowledge of that portion of the subject did not permit me to do it justice, and I was unwilling to give a second-hand treatment of it.

I wish to acknowledge the help I have received in the form of facts and ideas from nearly all the furnacemen I have met. I have tried to make specific acknowledgment in the text to those who have given me the most valuable information; undoubtedly I have missed some, but the omission was unintentional.

To Dr. E. F. Roeber, the Editor of "Metallurgical & Chemical Engineering," in which the book first appeared as a series of articles, I make here my profound acknowledgment of his helpfulness, patience, appreciation and encouragement.

To Mr. D. M. Liddell, author of the "Metallurgists' & Chemists' Hand Book," my sincere thanks are tendered for reading over my manuscript and finding in it many obscure paragraphs and errors whose presence I suspected, but, owing to too great familiarity with the text, could not see.

To Mr. Bradley Stoughton, Secretary of the American Institute of Mining Engineers, I am indebted for helpful and constructive criticisms on several of the chapters.

My attempt to cover the field has outrun the limits of one volume, and this will shortly be followed by a companion volume, "The Principles, Operation and Products of the Blast Furnace." The separation into two volumes is merely for convenience.

J. E. J. Jr.