Report on Dr. C. 311. Cresson's Cellular Gas Retort. 141

trifling difference in the level of the inner and outer projections, which represent the paving on the inside and outside of road, and which will not be increased by ruts.

C O M M I T T E E ON SC IE N C E AND T H E ARTS.

Report on Dr. Charles ~I. Cresson's Cellular Gas Retort. The Cummittee on Science and the Arts constituted by the Franklin Institute of the

State of Pennsylvania, for the promotion of the Mechanic Arts, to whom was referred for examination the Cellular Gas Retorts, invented by Dr. CHAnL~s M. CnEsso~, of Philadelphia, Penn.,

REPORT :--That the invention consists in arranging a system of cells in the walls and especially in the bottoms of the retorts, which cells are so connected, by omitting the dividing walls alternately at the two ends, as to constitute a continuous passage, opening at one end into the retort, and at the other, giving exit to the gas into the main. In this way the gas is maintained for a considerable time at a moderate red heat while it slowly traverses this passage. In the retorts in use at the Philadel- phia Gas Works, the cells are in the bottoms of the retorts only, and arc eight in number in each retort, each two inches wide, four inches deep, and six feet long; so that the gas is made to traverse slowly a space of 48 feet, and during the time thus occupied, is subjected to a regulated and moderate temperature.

The efti~ct of such an arrangement is two-fold ; in the first place, it must modify, to a considerable extent, the temperature of the body of ~he retort itself, which has thus interposed between it and the heat of the furnace-flues, the gases contained in the cells. The retorts will thus be less violently and more steadily heated, and the nature of the gases developed, may, as is well known, be thus considerably modified.

Secondly, it would seem possible that a material change in the chemical nature of the gases may be produced by the maintenance of this te,n- perature f,)r a considerable time.

Heretofore, these retorts have been exclusively employed in the manufacture of gas from wood, and tile practical result has been that, whereas, according to the experience of the gas works in the City of New York, the g,~s fi'om wood manufactured in the ordinary retort cannot be economically used, owing to ils low illuminating power; the gas from wood manufactured in this city in the cellular retort, exhibits at the present prices of wood and coal, a slight superiority in econo- mical value over coal-gas. The wood used has been principally COln- mon pine, and, as the apparatus has been used merely as an adjunct to the coal-works, and is comparatively on a small scale, no provision has been made for properly seas(ruing, dryinq, or splitting the wood. For the most part the wood had been distilled in large sticks, dried for a few hours only, and requiring some four hours to exhaust the volatile matters. Experiment, however, has shown that the capacity of the appa- ratus can be largely increased by diminishing the diameter of the wood, and by thorough drying. By proper attention to these points, the same weight of charge carl be burned off in 1½ hours with an increased yield

14'2 Franklin Institute.

of gas per pound. Iz~ this way, a retort that will y ie ld ordinari ly 4500 cubic feet of gas in 24 hours , can be made to produce over 9000 cubic feet in the same time. By careful working, 10,000 cubic feet have been obtain- ed with the same amount of fuel and labor as are ordinari ly used for two-thi rds that amount of coal-gas.

The fol lowing are the s ta tements of the results actual ly obta ined with these retorts : -

Experimental Trials. April 29 and 30, 1856. 6 retorts in action--duration of trial 48 hours.

Largo pine wood--3 hours charges. 14,400 pounds of wood produced 76,000 cubic feet of gas, Being 5"27 cubic feet to pound, or 15,800 cubic feet to cord. 6333 cubic feet to

retort in 24 hours. June 12 and 13, 1856. 6 retorts--3 hours charges--duration of trial 48 hours.

Pine wood split and partially dried. 12,000 pounds of wood produced 76,000 cubic feet of gas, Being 6"33 cubic feet to pound, or 18,900 cubic feet to cord.

July 31st, 1856. 6 retorts--hourly charges. Pine wood, split small, and dried. 14,400 pounds produced 62,000 cubic feet of gas, Being 4"30 cubic feet to pound, or 12,900 cubic feet to cord.

In this trial the charges were not thoroughly burned off--the charcoal being smaller but of better quality.

10,333 cubic feet to retort in 24 hours.

March l, 1855, to March 1,1856. Wood used in retorts. Gas produced. Fuel used, (coke exclusively.)

2,896,578 lbs. 11,860,425 cu. ft. 33,906 bus.

Average make per pound for year, 4.09 cubic feet. equal to 12,200 cubic feet per cord.

Maximum monthly make ~ 4.83 cub. ft. per pound. equal to 14,490 cub. ft. to cord.

350 cubic feet of gas were produced for each bushel of coke used as fuel. March 1, 1856, to March 1, 1857.

Wood used in retorts. Gas produced. Fuel used, (wood exclusively.) 1,840,265 lbs. 8,306,000 cub. ft. 1,380,000 lbs.

Average make per pound for year, 4'51 cubic feet. equal to 13.530 cub. ft. per cord.

Maximum monthly make, 5"61 cub, fL per pound. equal to 16,830 cub. ft. per cord.

Average charge t37 pounds per retort. " retorts in action 6.

Yearly production per retort 1,384,333 cubic feet. Average duration of retorts, 12 months. 18,000 cub. feet of gas produced per cord of wood as fuel,

As every inven t ion by which the price of gas is d iminished, either by increas ing the yield, by diminishing the first cost of the apparatus , or the expense of its main tenance , or by subst i tut ing o ther materials for those whieb have been heretofore exehts ive ly used in this manufac- ture, is of the greates t importance to the commun i ty , the c o m m i t t e e d e e m the gas retorts of Dr. Cresson to be a very va luable i m p r o v e m e n t , and r e c o m m e n d them to the attention of those e n g a g e d in the manufacture of i l luminat ing gas.

By" order of the Commi t t ee ,

Ph i l ade lph ia , J u n e l l t h , 1857. WIrJ.IAM HAMmTON~ ,/lctuary.