of temperature in the electric separator for the difference between the inlet and outlet temperatures disc to air-cooling was only about 25°F. There can be no question but that this separator through the electric action was almost completely freeing the gas from the suspended tar and water particles during the four or five seconds in which the gas was passing through the annular space twelve inches high between the electrodes. We were, however, not always successful in operating the separator continuously. Sometimes the silent discharge became disruptive when the action of the separator ceased until the silent discharge was restored. The disruptive discharge was most apt to occur when the cloth wrapped around the positive electrode had become coated with tar. Presumably the fine hairs constituting the points from which the silent discharge occurred had become matted together. Theoretically the positive electrode should remain clean because all of the tar particles should be blown away from it, and perhaps this desirable state may be attained in a commercial plant operating continuously. Trouble was also experienced with the insulation of the positive wire as it passed into the apparatus. Rubber insulated wire, wires insulated by glass and by successive layers of glass and paraffine as well as other devices were tried. None of them were entirely satisfactory. Leakage of the current could always be detected and sometimes it became excessive. Most of our time has been devoted to a study of proper form of electrode and to proper insulation. The power required to operate the electric separator cannot be given with any certainty. The transformer with which most of our experiments were made was in bad condition and required about .25 kw. for its excitation. It was not possible to detect with certainty any difference in the readings of the watt meter on opening and closing the high tension switch leading to the separator. More recently we have acquired an auto transformer much better suited to our work. Some idea of its operation may be gained by filter papers E, F and G of Plate I which show results obtained by filtering one-third of a cubic foot of gas in each case. E represents a paper taken at the outlet of the sep arator when the gas was passing but no electricity was being used. F represents a paper taken a few minutes later when the input into the transformer was .06 kw. and the instrument was set for 20,000 volts. G shows a paper in the same series with .10 kw. input and the transformer set at 30,000 volts. To obtain the amount of power actually used by the separator we should deduct from these figures transformer loss and leakage. The latter is undoubtedly high with our present installation. Our knowledge of the theory of this electro deposition is not sufficient to enable us to make any calculation as to the amount of power theoretically required. The suspended particles in some way acquire an electric charge possibly through the condensation on their surface of gaseous ions formed by the silent discharge. The particles thus charged are swept to the electrode of opposite polarity and deposited there. It will be seen, therefore, that the process requires a unidirectional current. If an alternating current is used it is not without effect, for there seems to be a coagulation of the suspended particles which gradually become large enough to settle through gravity. To obtain effective results a high tension direct current must be used and the apparatus must be so arranged as to obtain a silent and not a disrutive discharge. With a knowledge that almost complete separation of particles of tar and liquor suspended in coal gas can be obtained in a single electric precipitation, and the success of the electric process of removing smelter fume on the large scale at small expense demonstrated, it is well worth while to carry the experiments further. If the complete removal of tar at any desired temperature can be assured there will follow fascinating possibilities of increased economics in condensation, less expensive plant, better ammonia liquor, freedom from naphthalene stoppages, longer life of purifying material, and richer gas. University of Michigan. Ann Arbor, August, 1912. The President: The Secretary will read a letter from Prof. White bearing on the paper. The Secretary then read a letter of Mr. White as follows: Dear Mr. Chamberlain : On my return to the city to-day I find the envelope of papers to be read at the forthcoming meeting of the Michigan Gas Association. As I intimated to you some time ago, I do not see that I can be present at this meeting. Please express my regrets to any of my friends who may remark upon my absence to you. Plate I of our paper on the electrical separation of tar from coal gas has either been very badly printed in the copy which was sent to me or else the half-tone was a very poor one. I am tearing out the sheet of my own copy and returning it to you that you may note on the bottom line Paper E should be very much darker than Paper F; whereas, in this print it appears lighter. I should not like to have the cut appear this way in the various gas journals, and hope that if the trouble is due to a faulty half-tone, you will let me know in order that I may provide them with the photographs from which they may themselves make a half-tone. Regretting again that I do not see that I can be present, and thanking you for your past courtesies, I am Very truly yours, ALFRED H. WHITE. The President: Gentlemen, you have heard the paper by Prof. White and his assistants. It is so far an incomplete experiment and undoubtedly we will hear more about it next year so that I hardly think we can do much along the line of discussion. We will therefore proceed with the reading of the next paper entitled, "Gas Collection," by Mr. Frank J. E. O'Hara. Mr. O'Hara then read his paper as follows: GAS COLLECTIONS. Frank J. E. O'Hara. In these days of vast undertaking and complex business, human ingenuity has been busy in perfecting the art of accounting and I believe it is a recognized fact by the management of large business enterprises that proper accounting in its most minute details, is essential to the successful and economical conduct of their business. The paper, which I am reading, will treat in a general way upon the "Collection" end of this accounting, as followed by the Port Huron Gas Company. The writer will not venture the opinion that the system as outlined is the best that can be devised, but will say that from past experience, we have found it practical, efficient and economical in its results. We understand there exists a great diversity of opinion regarding systems to be employed in connection with the reading of meters, rendering bills, accounting for and collecting them. No two companies use exactly the same method, though all are striving to reach the acme of perfection in this respect. The collection of gas accounts is of much importance to all companies and the method of handling same should be as simple and accurate as possible and that is the plan followed by our company. I am safe in saying that we are successful. When a prospective customer makes application for gas, he signs a contract, as shown below: Order taken and Witnessed by Fuel.. Light... No........... Office-Solicitor. .191.... ............hereby make application to the PORT HURON GAS COMPANY for ..... ......Street, and agree to pay for the same promptly, at the regular rates and according to the rules of said Gas Company. ..further agree...., that the agents of the said Gas Company shall have free !........ Occupant. I hereby guarantee the fulfillment of the above obligation on the part of said Applicant. Owner. In this application he states he desires to use gas at a certain, address and that he will pay for same promptly at the regular rates and according to the rules of said gas company and further that the company shall have free access to the meter and its connections at all reasonable hours, and is at liberty to remove the same for any indebtedness whatsoever. As we do not require a deposit, the party is asked to kindly wait while the application is referred to the bookkeeper, who passes upon the credit. This is done through reference to his past account, the previous address or last place of using gas being shown at the bottom of the card and also by reference to the Bad Debt Ledger. If the account is clear, the credit is passed and the meter set. If there is an account standing against the applicant, the bill is then presented to him and if the bill is for gas consumed for a time greater than sixty days, the customer is told, in a polite way, that it will be necessary to pay the bill before a meter can be set. It is a rare occurrence that the account is not settled when presented. If the applicant is a new consumer, his general appearance, the locality in which he lives and his occupation are taken into consideration. If conditions warrant it, a regular meter is set; if not, he is asked to use a prepayment meter and sign a prepayment application, which differs from the regular |