tallized naphthaline, and any experience had in regard to the course of its deposit, method of prevention or removal, is sought by most managers.

That the amount of this crystallization is variable is probably evident to most managers; but a diversity of opinion exists as to the real cause of its profuse development or else to the best method of preventing its crystallization and deposit.

Naphthaline is a white crystallizable substance evolved by the distillation of bituminous coal. When crystallized it is a very delicate film, yielding to the gentlest touch, yet, under favorable circumstances, it compacts, and is capable of considerable resistance. It has a peculiar faintly aromatic odor, not unlike narcissus; is heavier than water, and is readily dissolved by naphtha.

During the fifteen years of my experience as engineer of the Cleveland Gas-Light and Coke Company, in the manipulation of the gas, varied results have been observed. In the process of condensing and washing the gas, our usual method has been to condense first and then to wash. At one time it was thought advisable to erect a spray washer between the hydraulic main and the condensers, as is the method in many gas works. Soon after there was observed a rapid accumulation of naphthaline in the drain leading to the tar- well, in the purifiers and pipes about the works, and also in the distributing mains in the streets. At a subsequent period these spray washes were removed and placed between the condensers and purifiers, used in connection with the purifiers, and very much less naphthaline was crystallized. During the periods mentioned, the heats of the benches were what is termed" high.”

During the past cold season, there was used with the coinmon bituminous coal, from 4 to 8 per cent. of cannel coal; the heats were not high; the gas was kept hot while passing from the retort-house to the condensers-about 150 feet-by encasing the pipe; the condensation was very gradual, by the use of open-air condenser,

and but a small amount of water used in the scrubber and no spray washer. During this period we had no crystallized naphthaline.

It has always been observed that wherever high heats were carried, more naphthaline was crystallized than with medium heats, and that when a bench was lightly charged, after being cleaned of carbon, and while hotter than usual, naphthaline appeared more abundantly than under ordinary circumstances.

My deductions from the experience at our works are as follows:

The crystallizing of naphthaline is caused first by "high heats," and the amount increased by rapid cooling of the gas by contact with cold water, cold pipes, and rapid cooling otherwise: and that naphthaline is more likely to be developed in gas made from slack coal than from lump coal. The remedy I would suggest for this annoyance is the use of a small percentage of cannel coal, in connection with the common bituminous coals, moderate heats, long exposure of the gas to hot pipes or other condensing operations, before reaching the cooling condenser; slow cooling of the gas and scrubbing with a small amount of fresh or ammoniacal water of moderate temperature; and, also, when found necessary, the introduction of a small continuous supply of naphtha into any horizontal pipes about the works, after condensation, or into the drips of the inlet and outlet pipes to the gas holders. The evaporation of the naphtha will dissolve the naphthaline crystals.

My deductions may not all be strictly correct, but my observations lead to these results.

Mr. Walker-I would like to ask Mr. Hyde as to the result.

Mr. Hyde-I can hardly answer that intelligibly. We have got big results this last winter, for the reason that we were running without seal.

Mr. Walker-What yield did you get?

Mr. Hyde-The yield has been very much greater

since removing the half inch and heats just as high; I cannot give from memory the exact figures.

Mr. White-Upon the subject of naphthaline, if I may presume to again address the Association, I had some troublesome experiences before learning its nature. High heats have been so constantly upbraided as the parent of this enfant terrible, and so thoughtlessly and unjustly, that I must try to rescue them from blame. I admit that high heats undoubtedly place us in position to be annoyed with this crystal, but so did the use of steam put us in jeopardy from railway accidents. Of late years we have been putting our brain work into our retort houses faster than in our other apparatus, and the result is the unfortunate under dissection. High heats, low seals, rapid evolution of the gases, their hasty removal from the retort, and their sudden plunging at a high temperature into the showers of spray washers, or through yards of chilling condensers, soon gave birth to the lusty and troublesome crystal nuisance that sheds its favors, like some divine blessing, upon the just and unjust, causing gas managers to drop into profanity.

The agency of heats in producing naphthaline lies simply in converting into a gas, at a high heat, olefiant qualities, that at low heats pass over as oils. In order to retain this (at that point) easily condensed, volatile oil in a gaseous form-three methods are open to us: We may mix free hydrogen with our coal gas at a high temperature; we may introduce into our coal gas, gas made from naphtha; or adopt the plan of having a long connecting main, protected from the atmospheric changes, between the hydraulic main and condensing apparatus, so retaining the crude gas as long as possible in contact with its own condensable vapors, and subjecting it to a gradual lowering of temperature. I have made a practice of introducing the water into my condensers at the "outlet" end and taking the overflow from the "inlet" end, so causing the gas to come first in contact with pipes somewhat higher tempered than I could

otherwise do, and so continuing my scheme of gradual cooling, I use but little water in actual contact with the gas, believing more in the efficacy of the dry scrubbing it gets in passing the divisions of the washer, than in water as a cooling agent in that stage. (I may say, parenthetically, that since my visit to Cleveland, I believe less than ever in the virtues of water.) Following these general views, I have succeeded in escaping any further trouble from naphthaline, save an occasional warning presence in my purifiers, when I accept the hint and look for something wrong back of them.

When gentlemen come to understand the chemical laws governing the deposit of naphthaline, the great step to its prevention will have been taken, and it will pass out of the category of nuisances and be blessed for its useful qualities.

Mr. McIlhenny-I would like to add a word to what has been said. I must say that I indorse, to a great extent, what Mr. Hyde says as to naphthaline. Now, I find that the promotion of crystallization of naphthaline is always at a point where the temperature is very much colder than the point from which it leaves the holder. The gas does not change its condition after it goes into the holder, and I do not think the theory which Captain White advances, that coming in contact with its own constituents, for any great length of time, will prevent its changing its condition by the condition of the atmosphere; for instance, you run a quantity of gas from a point-say 80°-when the sun is hot, in the spring of the year, and into the ground; say that it is then 30° where the gas strikes the service pipe, close upon where it enters the building, the volume in the service pipe not being so great the moment crystallization takes place. I think the condition of the gas is not changed by its contact with other constituents of carbon. We ought to acknowledge that high heats convert these light carbons into gas, instead of leaving them in their original condition.

Now then, my theory is that when these light carbons are converted into gas, it is done by high heats; that if you can distribute it in an even temperature, you leave no naphthaline; but if you cannot, if the temperature of distribution varies, then I think you cannot prevent it.

Mr. White-I will say, Mr. President, that the gentleman is merely carrying out in these remarks just exactly what I say — that the pipes from the hydraulic main to the condenser must be kept at an even or gradually lowering temperature. Clegg says, that the length of such a main should be ten feet for every inch of diameter you have in the hydraulic main. I find such a rule to work well enough in practice, and recommend it.

Mr. Littlehales-I have had some little experience in naphthaline, and my experience is precisely the same as the gentleman whose paper was first read, and the gentleman in the corner (Mr. White), as to the cause of it; but there is one little discrepancy, as it appears to me, in the gentleman's statement. He says that high heats are the cause of naphthaline-he also says that he cannot get the heats too high to suit him, and yet he argues that we should try to prevent the formation of naphthaline. Two things it seems to me are diametrically in opposition to each other. If a high heat is the cause of naphthaline, then let us have lower heats.

Mr. White-I was combating that theory, sir.

Mr. Littlehales-I believe it was Dr. Letheby who called the attention of the British Association to the fact that tar had a great affinity for naphthaline, and if engineers would only keep the gas long enough in contact with the tar, it would remove the naphthaline from the gas.

I believe that has been tried and been found to be a perfect success in every case. We once had a great difficulty with naphthaline. The cause was this: We were working at exceedingly high heats, and the condensing power was very inefficient. The engineer of the company, Mr. Cathels, had put up not much less than