9. Describe, with sketches, a cross, or four-way branch, for four-inch cast iron pipe, giving the dimensions to be used when it is provided with bells, and also those to be used for flanged ends, including the number of bolts and diameter of bolt circle. IO. What details of construction have been adopted in the manufacture of flat flame burners in order to ensure that the combustion of the gas shall take place as far as possible under the conditions stated in the answer to Question No. 10 of the Second Series for 1901? II. How would you test various samples of gas cooking stoves to determine which was most economical of gas and at the same time did the best cooking? 12. What are the objects sought in mixing sand with lime in making lime mortar and with cement in making cement mortar, and what are the qualities required in a sand to fit it for use in making mortar? (Answers to these questions are due September 1st, 1901.) ANSWERS TO THIRD SERIES OF QUESTIONS, 1901--FOURTH SECTION--PRACTICAL CLASS--AMERICAN GAS LIGHT ASSOCIATION. I. Name the principal gas coal fields of the United States and Canada, and give the general characteristics of the coal from each field. Ans. The principal gas coal fields of the United States are located in the Appalachian coal field which stretches along the Appalachian mountain range from New York to Alabama, but gas coal is also found in each of the other great coal fields, viz.: the Middle in Illinois, Indiana and western Kentucky, the Western in Missouri, Iowa, Nebraska, Kansas, Arkansas and the Indian Territory and the fields in the far West, the limits of which have not yet been clearly defined nor their resources fully developed. Among the gas coal districts of the Appalachian field the Pittsburg district which lies immediately east and south of Pittsburg on the Allegheny, Monongahela and Youghioghenny Rivers is prominent. The coal from this district is comparatively hard and dense so that it can be transported without excessive breakage, and yields a good amount of gas of good quality and a clean hard coke. The percentage of sulphur contained in it is small, being usually well under 1%. A fair gas coal is also found in Jefferson and Beaver Counties, Pennsylvania, but this coal is not quite as good as that from the main body of the Pittsburg field. Another important field is the West Virginia field located in the northern part of West Virginia along the banks of the Monongahela River. The coal in this field is very similar to that obtained from the Pittsburg district, but is less able to stand handling without disintegrating and is apt to contain more sulphur, although some samples show very well in this respect. The Kanawha district, also in West Virginia, extends back for about 30 miles on each side of that portion of the Kanawha River between Kanawha Falls and Charleston. The coal produced here differs only slightly from the coals mentioned above, except in being apt to contain more sulphur than is found even in the coal mined in the West Virginia district, the percentage running up as high as 12% in some samples, although as low as o 6% in others. Cannel coal is also found in paying quantities in this district. Kentucky possesses a little gas coal but hardly enough to be taken into consideration if it were not for its large deposits of rich cannel coals. The best known of these is the Breckenridge, which besides giving off a large amount of rich volatile matter yields also a fairly good coke which can be mixed to a proportion of 10% with the coke from ordinary gas coal without depreciating the latter. In Tennessee good gas coal is found in Scott and Anderson Counties, while in Campbell County an excellent cannel coal is mined which is similar to the Breckenridge and is known as Jellico cannel. The gas coal is a clean hard coal fully equal in all respects to that obtained from the Pittsburg district. In Alabama there are three coal fields, the Cahaba, the Coosa and the Warrior, in each of which some coal is found which can be used as gas coal, but the best coal for this purpose comes from the Corona seam in Walker County. This coal is clean and hard enough to bear handling well. Although Ohio, Indiana and Illinois produce coal that is used locally for gas making, they cannot be considered as gas coal districts, since the coal is only used for this purpose when the gas works are practically over the mines, and Pennsylvania coal is in demand throughout these States for use in preference to the local coal. In Kansas the Cherokee field produces gas coal that is good in every respect except that of the amount of sulphur contained in it, and this runs from 22% to 5% and even as high as 8% in some samples. The Choctaw country in Indian Territory yields a coal which is clean and hard, stands handling and produces a good coke. closely resembles the Pennsylvania coals although it contains more sulphur and ash than the latter, the percentage of sulphur being a little over 1%. The Trinidad field in Colorado also furnishes a clean bright coal that is low in sulphur and is said to give a good yield of good quality gas and from 60% to 70% of compact coke. On the Pacific coast the South Prairie and Roslyn mines give a coal from which a fair amount of fairly good quality gas can be obtained and which is low in sulphur but produces a soft, friable and comparatively poor coke. The principal gas coal fields in Canada lie on Glace Bay and Cow Bay in Cape Breton. These provincial coals were formerly used quite extensively by gas works situated on the Atlantic coast of the United States. They yield a good amount of gas of a quality better than average, but they disintegrate easily, contain a fairly large amount of sulphur and are very susceptible to spontaneous combustion. At the present time their use has been practically abandoned in the gas works of the United States. Average analyses of some of the coals mentioned above follows: 2. Describe with sketches, a retort mouthpiece, showing the manner in which it is fastened to the front of the retort and the arrangement for making a gas-tight joint between the mouthpiece and the lid. Ans. Retort mouthpieces are invariably made of cast iron, and such a mouthpiece may be described as being a tube of suitable cross section provided at one end with a flange of the size and shape of the front end of the retort and at the other with a faced lip, the cross section of the mouthpiece at this face being either round or more generally elliptical, no matter what the shape of the retort. The lugs required for supporting the lid and its fastening are cast on the sides of the mouthpiece, projecting beyond its faced edge, and an opening to allow the gas to escape from the mouthpiece is made at the proper place in the sides, at which place is also provided a bell to receive the lower end of the standpipe. The distance from face to face of flange and lip varies from 14" to 16", the shape and dimensions of the flange and the opening at the back should be the same as those of the retort and the width and height of the front opening should also be the same as the corresponding dimensions of the retort, although the shape is, as stated, usually elliptical even with D shape retorts. The mouthpiece is generally fastened to the retort by means of %" bolts about 9" long, inserted in holes parallel to the axis of the retort made in that portion of the retort wall at the front end which is thickened for the purpose. Each of these holes opens at its inner end into a square recess extending in from the outside of the retort. A square nut is put in this recess and the bolt, which is threaded at each end, is inserted in the hole and screwed into the nut. The spaces left in the holes around the bolts are then filled with iron cement, made of one part by volume of fine iron borings or filings and two parts of fire clay moistened with a solution of sal ammoniac, the front of the retort is plastered with a layer of the same cement and the mouthpiece is put on and drawn up tight by screwing down the nuts put on the bolts. The faces of both retort and mouthpiece should be wet before the joint is made. A great objection to this method of fastening mouthpieces to retorts is that as the bolts burn out after the retorts have been in use for some time, the mouthpieces become loose and it is impossible to keep the joints between them and the retorts tight. It is also impossible to replace a broken mouthpiece by another in case of necessity. To avoid these faults clamps built into the |