ments on a very extended scale, but in a recent enlargement of our works it became necessary to throw a portion of our apparatus out of use, so that I failed to carry the matter as far as I otherwise should have done. I simply give my results as suggestions, and hope that some one else will be interested in the matter, now that there is the ability here to carry the investigation so much further. MR. HELME-It seems to me that with the low temperature for four hours, you wouldn't get all the valuable vapors out of the coal. MR. RANKIN-But I am satisfied I did, sir, and I think you would find it well worth your while to try a few experiments in regard to low heats upon the gas producing elements in coal. A gentlemen remarked to me once that he was satisfied that with low temperatures he could take all the gas out of the coal, and if he had red heat for four hours I will admit that he could. You will be surprised at the rapidity with which these volatile materials pass out of the retorts. But what I gave you in regard to that in the paper is absolutely true-not the result of one observation, nor ten, but a series of experiments extending through three or four months. MR. HELME-What is the size of your retorts? MR. Rankin—I use a five inch wrought iron retort, so that I can raise or lower the temperature with impunity. MR. MCMILLAN-Which was the best coke-that made from. low heats or from high heats? MR. RANKIN-I havn't compared them very carefully. All the coke made from high heat is quenched with water, and is, of course, very much heavier. In my experiments I used no water at all, so that I had every particle of coke. I weighed it, both before and after, and I have all the data in my memorandum book at home. THE PRESIDENT-You weighed it in an incandescent state? MR. RANKIN-Yes, sir. MR. HELME-Would you use two or three retorts at low temperature, and two or three at high, or how? MR. RANKIN-My opinion in regard to the matter would be to use the ordinary retorts in the benches we now have, and in the place of D retorts would have partition walls, say two inches thick, and would work through retorts-take the gas in at one end and out at the other-would charge at both ends with the coal. I am satisfied, from experiments that I made, that it is impossible to decompose vapor given off from many retorts, until the mass of coal has attained that degree of heat necessary for decomposition. MR. HELME-It does seem to me that, with retorts of the ordinary size, and running a full charge, at a low temperature, it would be impossible to get the gas out of the coal in four hours. MR. RANKIN-Notwithstanding that it is true that it can be done. THE PRESIDENT-If there are no more remarks to be made on the subject of this paper we will pass on, and listen to a paper prepared by Mr. Thomas Curley, which, at his request, will be read by the Secretary. ON NAPHTHALINE. By Thomas Curley, of Wilmington, Del. MR. PRESIDENT AND GENTLEMEN: At the request of our worthy Secretary, I have prepared a few remarks on the system which I employ for the purpose of preventing, or at least, less ening the deposition of naphthaline crystals about our works, particularly in the inlet pipes to the holders, which had formerly given us so much trouble. In doing so I have not considered it necessary to go into the history of this substance and its characteristic properties, except to revert slightly to its formation or production. In the destructive distillation of coal in gas works, naphthaline vapors are always given off, until the greater portion of the bituminous matter of the coal is expelled; whether the heats be what we term high heats or low heats, those vapors are always given off, and will crystallize or not, just in proportion to the temperature of the retorts, and the quantity of light vapors in the gas. If the temperature be moderate or low, a considerable quantity of light hydrocarbon vapors will escape decomposition, and their presence in the gas mixture will prevent the naphthaline vapors from crystallizing; if, on the contrary, our heats are extremely high, the greater portion of those light vapors is decomposed, forming new and stable compounds, which have no neutralizing effect on the naphthaline vapors; another portion is absorbed by the tar, the remaining portion, which is held in sussuspense by the gas, is too small in volume to counteract the tendency of the naphthaline vapors to crystallize, hence the trouble to which we are so often subject. Under these circumstances what is best to be done? We cannot return to low heats, it is unprofitable; we cannot afford to rely on the tar for the extraction of those vapors out of the gas, we risk too much in doing so, because the tar will make very little distinction between the naphthaline and light vapors; it will absorb both. The free use of coal oil is undoubtedly an effective remedy, and will prevent the formation of crystals, while adding to the. illuminating power of the gas; and the only question to be considered, is its safety and cost. The process used in our works is in one respect the result of necessity. I found the inlet pipes to the holders stopped so frequently that I was compelled to use steam every few days, that by dissolving it we might pump it out. The trouble and inconvenience became so great that I resolved to expel from the tar the benzol and naphtha series of hydrocarbons, and mix them with the gas, knowing them to be great solvents of naphthaline. With this view I constructed a small still and separator; in the still I placed a small coil of steam pipe, and caused the tar I made to pass through this still. I examined the inlet pipe immediately before heating the tar, and I found three-quarter inch of crystal on the inside. I then heated the tar to about 170° and allowed its vapor to pass on and mix with the gas. After the expiration of twenty-four hours, I again examined the inlet pipe, and found it as clean as when new, showing that the expelled vapors had dissolved the crystals which had been formed. This was in January, 1876. Up to this time we used from 5 to 8 per cent. of Cannelton Cannel, but since then we discontinued its use altogether. In the process the tar (after the expulsion of the light vapors) and liquids, flow on to their respective receptacles. It is automatically arranged, and requires no attention, comparatively speaking. We get the light vapors out of the tar without any expense, and utilize them first as solvents, and secondly as illuminants. It is well known that even small quantities of light, hydro-carbon vapors add materially to the illuminating power of the gas, and hence, the greater the quantity the tar can yield, the less the danger of napthaline crystals, and more illuminants will be added to the gas. But, as I have already intimated, I may carry the process of carbonization to such an extent as to leave very little of that light vapor in the tar. In such a case there will, of course, be no substance left in the gas, of a solvent nature, to counteract the crystallization of the naphthaline vapors. Under such circumstances they will undoubtedly crystallize.. But such policy I consider as being very doubtful, indeed. I would not, on any account, decompose all of the light, hydrocarbon vapors in the process of distillation; for, by doing so, I would first rob the gas of one of its principal elements of light, and leave the napththaline vapors free to crystallize according to their nature; second, by the breaking up of these vapors they become resolved into numerous light carbides, the principal portion of which being marsh gas and hydrogen, and destitute of luminosity, only necessitates the subsequent enriching of the gas by cannel or oil. Gentlemen, I hold that by proper manipulation our principal coals (i. e. coal from Westmoreland region), need no enriching material to maintain a yearly average of 10,800 feet to the gross ton, and a power of 17 candles. This has been my experience, and, for aught I know, others may have far exceeded it. What I state with regard to our results, be they favorable or not, can be substantiated by the president and directors of our company. The comparative result, thus far obtained in our works (taking the years 1875 and 1876), shows a gain of 2 per cent. in yield, and of candle power 48-100; the average candle power for 1875 was 16.60, and for 1877 was 17.08. Our freedom from naphthaline crystals is one of the most gratifying results obtained, and was unknown to us before. In 1875 we used cannel; in 1876 we used none, showing conclusively that it is to our advantage to continue the process. I don't profess to have discovered the fact that benzol and naphtha vapors will dissolve naphthaline, or add to the illuminating power of the gas; but only the simple and inexpensive method of getting and utilizing those vapors. Whatever important and startling discovery there may be in the future, in the interests of gas manufacturing, one thing is imperative at the present time, and that is, to look after, collect, and utilize everything committed to our charge, whether. it be the leakage of mains, services, meters, etc.; or the constructing and setting of retorts, their temperature, and that of our condensers or purifiers. As the mass of matter is made up of atoms, so we will find that our success depends very much upon the aggregation of small things. At the conclusion of Mr. Curley's paper, the President said: Gentlemen: I have another paper on the same subject, which has been prepared by Captain Dresser, and as the Captain is a very modest man, if he desires it, I will read the paper for him. CAPT. DRESSER said: Gentlemen-I am afraid you will all get tired of this subject before you get through with it. However, I haven't prepared much, and I want to state, to begin with, that it isn't any of it mine. [Laughter.] ON NAPHTHALINE. By Capt. G. Warren Dresser. MR. PRESIDENT AND GENTLEMEN OF THE AMERICAN GAS LIGHT ASSOCIATION: In presenting for your consideration, the results of some study of this subject, it is my aim to collect and |