PREFACE TO SECOND EDITION: The first edition of Coke was issued by The Colliery Engineer Company, of Scranton, Pennsylvania, in the year 1895 and was the first treatise on this growing and important industry published in the United States of North America. This edition was exhausted over one year ago. In the great progress of industrial manufacturers so manifest in the United States, this interval of nine years since the appearance of the first edition has retired some of the former methods in the manufacture of coke, and introduced many new ones. This advance in the progress of the industry has been induced by the large increase in the demand for coke, arising from the expansion in the use of steel and iron in architectural construction, as well as in railroad supplies. In the manufacture of these materials, a pure quality of coke fuel is an imperative necessity, and with the consequent large demand on the best coking coal fields, it has become necessary to extend coking operations outside these fields to regions possessing coking coals of a lower grade, requiring, in most cases, cleansing from the two principal impurities, slate and sulphur, by the modern processes of crushing, classifying, and washing. This necessary preparation or cleansing of coals for coking has been an inviting field for mechanical experts in which to devise machinery for this special purpose. It has also impressed the necessity for studying the several conditions in which these foreign matters are found in coals, so that proper machinery could be devised to meet the several conditions necessary for eliminating slate and sulphur. This department of the coke industry has, during the past decade, made commendable progress, especially in the preparation of the coal for introduction into the washer, in disintegrating the lumps of coal to certain sizes, and in the classification of the crushed product as it is being conveyed into the washers. This important auxiliary in the manufacture of coke enables the lower qualities of coals to be utilized in the production of an acceptable metallurgical fuel. In addition to this coal-cleansing auxiliary in the coke industry, an additional element has been introduced, meeting the conditions of some coals low in bituminous matter dry coals in a fairly satisfactory manner. These dry coals, low in fusing matter, could not be made to produce the best possible product in the usual open beehive coke oven. To meet these exceptional conditions, the retort coke oven has been introduced it is made in several types, but the different types have one element in common the retort or closed-chamber principle, which affords a quick heat and permits the utilization of the small content of volatile matter in these dry coals. The large cost of these retort coke ovens, with the additional expense of the apparatus for saving the by-products of tar and ammoniacal liquor, has prevented their general introduction. In addition to the large cost of installation, a retort-oven plant requires a supply of coal for a long period to cover the investment in the plant of ovens...