consumers on the line to discontinue the use of gas during a certain hour on a given day, or by shutting off the gas at such time, from all the meters connected with the particular line of mains to be tested.

I trust I have said sufficient on the subject, and if it leads to effecting an important saving to a single gas company, or a saving of a single life, I shall consider that I am amply repaid for my labor, and I shall trust that you will also be repaid for the time I have occupied.

At its conclusion the President said: Gentlemen, there are two more papers to be read, and it may be expedient to dispense with discussions and remarks until after these two papers have been read, and then, if there is any time, devote it to discussions. We meet to-morrow at nine o'clock, and have only two hours, until eleven o'clock, and if there is no objection, with the understanding that the members can recur to this paper after these remaining papers have been read, we will proceed with the reading of papers, and I will call upon Mr. Benson to read his paper On the Temperature of Retorts at Different Periods of the Charge."

66

TEMPERATURE OF RETORTS AT DIFFERENT PERIODS OF CHARGE.

By Frederick S. Benson, Engineer Nassau Gas Light Company, Brooklyn, N. Y.

The subject of heats of retorts at different periods of their charge, having been made a matter of record at the annual meeting of the New England Gas Light Association in February of the present year, from data furnished by M. S. Greenough, Esq., of the Boston Gas Works, and published in the American .Gas Light Journal, vol, xxvi, page 102, it might not be out of place to add another page to this history, a brief account of a series of experiments performed at the Nassau Gas Light Company's works, Brooklyn, being made the subject thereof.

The settings employed in these experiments were clay retorts, 14" X 26" X 9 feet, sixes and are what is commonly known as skeleton, viz., a barely sufficient quantity of brick and tile to

properly support the retorts, and no more. These benches being so widely dissimilar to those used in the experiments at Boston, mentioned before, afford a fair comparison between the two theories of setting retorts, one assuming that the least quantity of brick and tile used, after the retorts are properly shielded from the direct action of the flame on the former is more profitable, thus leaving the retorts to more quickly recuperate from the effects of a fresh charge of coal, or of cleaning the furnace fire, and attain their maximum temperature, although they may show a lower temperature during such time.

The other, that a larger amount of brick and tile employed in the setting is more favorable, from the fact that such tile serve to store or accumulate the heat attained during the later portion of the charges, and, in so doing, retain the heat of the bench at a more equitable temperature, or with less sudden variation, during the operations of charging retorts or cleaning fires.

There can be no question as to the theoretical damage to retorts by a constant rise and fall of temperature of any great extent, yet, practically, such variations as were shown to exist by the experiments about to be explained, were not worth taking into consideration, and it will be shown by the following data, that such large variations, or extremes of temperature, as might be expected, or that have commonly been supposed to exist. are not obtained.

The same general apparatus and formula were used in this case, as well as weight and description of coal as that used in the investigation mentioned before, that the results might be compared as to the different settings, and as the apparatus and formula may not be fresh in the memory of members, I will venture to explain them.

Two pieces of iron were used, weighing as nearly five pounds, . each as possible: these were round, and provided with an eye in the end to facilitate their withdrawal from the retort. A frame or truck to slide these irons to about the centre of the retort, and on the top of the charge of coal; the object being to have them as nearly as practicable, in the same position in the retort in every instance; these trays were supported by legs in

the mouthpiece, and by two standards in the rear end. A galvanized iron receptacle for holding forty pounds of water, two standard thermometers accurately divided, two wooden paddles to agitate the water in the iron box, that it might be of even temperature throughout, and hooks to remove the irons from the retorts while hot, and transfer them to the water for immersion.

The process consisted in placing the trays for the irons into the retort after it was charged with coal, with one of the irons on the same, a wire hook attached to the iron, and coming out so far front as the lid, and closing the lid.

At the expiration of thirty minutes the lid was struck (this operation being rendered comparatively easy by using the patent Eureka lid), another hook inserted into the eye of the hook already in the retort, and the iron drawn forward to the front of the retort, the first hook was then allowed to drop to the floor, and it was carried to the water and immersed, at the same time a fresh iron was substituted in the retort and the lid closed.

The average time that elapsed from the time the lid was opened till it was closed for this portion of the experiment was twenty-eight seconds, and the average time from the instant of opening the lid to the time the iron was immersed in the water was ten seconds. It will therefore be seen the iron had those ten seconds to part with a small portion of the heat, but as this was a constant quantity throughout the series of experiments, a fair comparitive result could easily be obtained.

Before the immersion of the iron the temperature of the water was carefully noted, and after the immersion the rise of temperature of the water as indicated by the thermometer, carefully observed.

When the iron was exactly the same temperature as the water, which was ascertained by placing the back of the thermometer in contact with the iron, a note was made of the water's temperature.

The following formula was then used to ascertain the maxi

mum temperature of the iron (supposing the temperature of the retorts to be the same) :

At the date of the first experiments there were but four benches under fire-three on one side of the retort house and one on the other. Of these the middle bench was selected, having a working bench on each side, and one at the back, thus giving a fair result of any bench, should they all have been under fire. The two middle retorts were selected for the experiment, it having been shown by trial that they were a fair average heat of the whole bench.

The first trial was made on Friday, July 20, 1877, commencing at 11.30 A. M or thirty minutes after the charge had been made.

The bench was charged with 1380 lbs. of coal, 230 lbs. to each retort, of which 50 per cent. was Block House from the Provinces (very fine), and 50 per cent. Penn (good run); two irons were used, one being placed in the same retort after the first was withdrawn, and thus alternated during the whole four hours of the charge; each iron was therefore exposed to the heat of the retort thirty minutes.