a probability, of any accident happening from an installation of that kind, provided the wiring has been done properly. All the switches, and every connection where the copper is to be exposed, must be outside of the building; then, with moisture-proof sockets on the inside which are gas-proof as well, the question of danger is entirely eliminated.

MR. C. W. HINMAN (Boston):-I have not had charge of gas works, but speaking from what knowledge I have I would say that it is a safe installation and is a very desirable one, to use for lighting the purifying house.

MR. E. E. WITHERBY :—I would state in further confirmation of that, that without an exception every purifying house that we have that is in use, and in fact all other portions of the works, are always wired, and incandescent lamps are used everywhere. It is a thing I would recommend under any and all conditions.

MR. E. J. DONAHUE (Philadelphia): -I would like to ask what the equipment is; and if the wire is in pipes?

THE PRESIDENT:-The question assumes that the switch-board is outside the building, and that the wiring is in iron pipes.

M. E. J. DONAHUE:-I think it is perfectly safe provided you use what is known as keyless vapor lamps, for then there is no possibility of a spark inside the house. Of course there is the possibility of a man carrying a bar or ladder around in the purifying house, and by accident breaking a globe. In that case there would be an explosion, if an explosive mixture is present. I think it is perfectly safe and recommend such installations. I wish to state further that if there are lamps in the purifying house which are equipped with keys, and if the wiring is not enclosed in pipes, it will be very dangerous to illuminate the purifying house with electricity.

MR. L. D. SPRAGLE (Johnstown, N. Y.):-My experience with gas purifying houses, and with explosions, did not include anything with reference to electric lighting. I consider the use of electric lights in purifying houses eminently proper, but we have not put them in, although we produce and sell electric lighting: the opinion being presumably on the part of our directors that it was an unnecessary expense. Further than that I have nothing to say with regard to it.

MR. E. E. WITHERBY:-Without any question the wiring should

be enclosed in interior conduits or iron pipes, which are insulated on the inside. Then no joints, or fuse, or branch-blocks of any kind must be allowed inside the room where there can be a possibility of an explosive mixture being present. The insulated wiring, with moisture-proof sockets, and switches outside the building, will effectually prevent any possible chance of explosion, even with the most dangerous explosive mixture, if the work is only done properly.

MR. C. A. LEARNED (Meriden, Conn.):-Last year we put up a new purifying building, and, as we run both gas and electricity in our town, we wired the purifying house, and put our main switch and the fuse-boxes just outside the door. We put our wires in iron pipes outside and in wood mouldings built for the interior work. The bulbs are enclosed in what are called Newgard receptables, simply as an extra precaution. The receptacle is a kind of Mason jar with rubber casing on the top of it. We have had no trouble, and do not expect any.

MR. E. J. DONAHUE-I have noticed several installations of electric wiring in purifying houses. The interior was well done, but the switches were not located in what I would call a safe place. They were enclosed, in a box, and located on the outside wall of the purifying house, within a foot of the door. Turning on or off a switch makes a spark, and if an explosive mixture was flowing through the doorway at the same time the switch was turned on, it is possible that there would be an explosion. To make the installation perfectly safe, the switch should be located some distance from the house, say fifty feet.

THE PRESIDENT:-Another question is:

How long is it economical to run a Lowe water-gas apparatus without cleaning the checkerbrick? Is it economical to let down the machines for twenty-four hours every week in order to burn out the carbon which has accumulated on the checkerbrick?

Will Mr. Norris answer this question?

MR. ROLLIN NORRIS (Philadelphia):-I hesitate to give a categorical answer to a question of that kind. I believe in cleaning whenever there is a falling off in efficiency sufficient to justify the expense of cleaning.

As far as the burning off is concerned-a good deal can be done in the way of postponing the cleaning by occasionally burning off

the carbon by the air blast. Of course it is objectionable to burn off the carbon when the set is in constant operation by simply stopping for an hour or so, burning off and then going ahead and making gas. That completely disarranges the temperatures in the fixing chambers, and it takes some time to get things back into the normal state.

MR. J. E. NUTE (Fall River, Mass.):-I think Mr. Norris has covered the ground entirely. The intervals in which it seems advisable to clean the checkerbrick depend altogether upon the manner in which the machine has been running. A clean machine, if improperly run, very soon gets clogged up and requires re-cleaning or burning out. If the machine has been run properly it will last a considerable time without burning out, but just how long I am not prepared to say. I generally run a machine three months without cleaning, where it is run almost continuously. I do not know what the usual practice is in this regard. I think it is safe to say that it will run that length of time at any rate.

MR. H. K. MORRISON (Concord, N. H.):-My experience has recently been with a machine run intermittently; this requires more frequent cleaning. It is an easy matter to clog up a machine even at the very start. It depends upon how the machine is run whether you have to clean it once a week, or only once in six months.

THE PRESIDENT:-We will now listen to Mr. Littlehales' paper. "Retort Ovens as Producers of Illuminating Gas."

MR. T. LITTLEHALES (Syracuse, N. Y.):- Before reading my paper I would mention that the two tables which appear in the paper were intended to figure at the end, as an appendix. They are simply details of figures which will enable you to check up my figures.

(For Paper see Appendix page xlvii)

THE PRESIDENT:-You have heard Mr. Littlehales' very comprehensive paper. Who is desirous of discussing it?

MR. C. G. ATWATER (New York City):-I want to express my gratification at hearing so hearty an endorsement of the retort oven as a gas producer from a gas engineer of Mr. Littlehales' wide experience, and particularly to welcome the nomenclature he uses in terming them "retort ovens." It seems to me that the coke oven, in turning from its wasteful courses in the wild places

of Pennsylvania to take up a better and more economical mode of life within the confines of civilization, ought to adopt a name that does not carry with it the recollection of blinding smoke and reddening skies. The term "retort ovens " may not be entirely new, but it is good. But I hardly think that Mr. Littlehales' closing statement is quite as hopeful as the array of facts he cites will justify. He says, in effect, that where there is a market for a firstclass foundry coke at good prices, the retort oven will produce gas at a lower price than the gas retort. This is limiting the retort oven to a very small field outside of the furnace coke precincts. That good coke, sufficient for all the requirements of the modern blast furnace is made in retort ovens, has, I think, been pretty fairly demonstrated. Sydney, Dunbar, Johnstown, Sharon, Wheeling, Glassport, and the new plants being built by the United Gas & Coke Company for the Lackawanna Iron Company at Buffalo and Lebanon, and for the Maryland Steel Company at Sparrows Point may be fairly said to have proved that proposition, in spite of the non-adherence of the United States Steel Corporation. But it is not the making of blast furnace coke that interests the members of the American Gas Light Association. There are relatively few locations where retort ovens making blast furnace coke can be placed in which their full gas capacity can find satisfactory outlet, except where a large part is used in steel heating furnaces or under boilers, which are uses no coal gas plant can dream of supplying in these days. Nor, I hope, is the field limited by the market. for a foundry coke. The demand is regular and the prices satisfactory, but the volume of business is not sufficient to make the industry of importance by itself, nor would it affect the gas field one way or another. But it is the introduction of coke in domestic use, railroads, and industrial establishments throughout the cities and the towns of the United States, wherever soft coal is now used, and in some places where anthracite coal is employed, that will herald the appearance of the retort oven in the gas field. That is the gist of the problem. When the soft coal that is now shipped into nearly every city in the Union is required to pay the toll of its almost useless and always smoky hydrocarbons by passing through a retort oven, before it reaches the furnaces where it is to be used, then the gas making side of the retort oven will have come into its own. And that this hope is not without justification we can judge from the success of the Everett Works in disposing

of about 1200 tons of coke a day continuously for over a year past. That this success is not regarded by experienced gas men as ephemeral is shown by the plant almost exclusively for theirown use, built for the Hamilton Otto Coke Company, and the one in course of construction at Camden, for the South Jersey Gas, Electric & Traction Company.

And therefore I will ask Mr. Littlehales' consent to the following proposition: In the average town where there exists a minimum daily demand for the surplus gas from at least 50 retort ovens, and where the community already consumes enough solid fuel to give the equivalent coke a fair chance for introduction on its merits, there retort ovens will justify their existence.

MR. F. EGNER (Norfolk, Va.): -I have read Mr. Littlehales' paper with much interest, and when I first saw it I was sure that he would give us something that was worthy the high standing of this Association. That by-product coke or retort ovens, as Mr. Littlehales designates them will receive careful consideration, cannot be doubted, they having already attracted the attention of notable men in the gas business. This was shown me by a conversation which I had with Mr. Goodwin Newton, the President of the Imperial Continental Gas Association of London, some years ago, who at that early date seemed to favor them. I think the whole question may be considered in connection with the careful study of another one: Will it pay? I am willing to take a great deal that Mr. Littlehales says on his word, because I know that he has been a careful manager and is a thorough gas engineer; and therefore when he makes a statement on any subject, and states he has given it his careful consideration, as he has in this paper, I will take it for granted there can scarcely be any doubt about it at all-even if there might be a difference of opinion. But in going over his figures, I find that there are some statements made which may easily be questioned with him. Take for instance his statement as to the cost of carbonizing coal. He states that a ton of coal is carbonized in these coke ovens for twenty cents and less. That is about the substance of his statement, as I understood the paper. He has stated that in gas works the cost of carbonizing per ton would be about ninety-five cents. I know that with ordinary horizontal retorts and with machine stoking, the cost for labor can be brought down to twenty-five cents per ton; while if inclined retorts are used it will go below