which deposites on the checker brick, for there are very few, if any, oil sprays in the market today that are so perfect as not to leave any unburned oil.

In regard to the candle power or B. T. U. value, in using this blue gas with coal gas, I am aware of the various restrictions and regulations operating in the nature of City Ordinances and franchise requirements in regard to candle or B. T. U. values, all of which are calculated to cause gas companies to deliver gas to its customers of a high standard. Matters pertaining to this end of the business are now under advisement in New York City, a committee having been appointed by the state to fix a standard. The same matter has been under consideration for a long time in Great Britain, where the Gas Companies have asked for a standard equal to 538 Gross B. T. U.'s per cubic foot with an allowable minimum of 122 calories, or agreeing to furnish gas containing not less than 484 Goss B. T. U.'s per cubic foot.

Answering Mr. Blauvelt in regard to a reduction of calorific value, would say there is an approximate drop of two candles when using about 12 per ct. blue gas, however, due to the increased flame temperature of the mixed gas, even a greater incandescent of mantle light was obtained, hence two standards (Candle Power and calorific power) are disregarded, yet a better gas is obtained when considered for heating and also, of course for incandescent mantles. The loss in candles in unquestionably due to C. O. 2 contents and is principally caused by using the regular Lowe Water Gas sets, which sets are not designed for the efficient manufacture of blue gas. On proper machines especially designed for making nothing but blue gas, then the reduction would hardly be noticeable and certainly not without a very careful analysis.

Further answering Mr. Blauvelt's questions I can say that the data in this paper is based on mixing the blue gas with coal gas in the foul main. I fully agree with Mr. Blauvelt that in introducing blue gas directly into the retorts that such practice would be more profitable, not only that, but that also considerably better results could be obtained. I will merely state at this time that we have already completed a system by which we not only intend to introduce the blue gas into the retorts, but actually

manufacture the blue gas in the retorts. I am not in a position as yet to touch on the merits of this experiment but undoubtedly can throw considerable more light on this subject on our next year's meeting, if such should prove of sufficient interest to the members of this association.

As to the elimination of naphthalene by the use of blue gas, which is questioned by Mr. Blauvelt and mentions that the true explanation for the reduction of napthalene contents could be found on the following page, referring to the scrubbing of mixed gas with pintsch tar or water gas as the real remedy for the accomplished reduction. To this I can state that on the same page I very plainly say that we had previously, for almost four years used pintsch tar in our last scrubber with straight coal gas, but without any material effect until we introduced blue gas in connection with the coal gas.

In regard to a larger yield per pound of coal it is my contention in view of the fact, that the blue gas practically enters the hydraulic main free from Hydrocarbon a portion of the highly luminous constituents as carried forward by the coal gas is picked up and retained, which fact, has been fully proven in our two years practical experience as well as by Mr. H. E. Jones of Uxbridge, England.

It is of considerable regret to me that for certain reasons I had to eliminate considerable valuable data on this subject which would have given a clearer conception on our system and results obtained from the use of blue gas. I may further state that the system we are using in manufacturing blue gas is not along the lines of Prof. Lewes' process. For the very fact that we are introducing our blue gas into the hydraulic main at a considerable higher temperature than as given in Prof. Lewes' paper on this subject read in 1901 at the International Engineering Congress. The system we are using follows more along the line of the one introduced in Europe some years ago by Kreamer and Aart, and which has met with great success and is quite extensively used, especially so in England and the Netherlands.

Mr. Hewitt: Mr. Weber has gone into the very realm that I hoped we could get into. If we can get this ordinance, and if

the American Gas Institute that has been considering the matter for so many years ever brings to fruition this effort to fix a standard, and if that standard follows closely the standards that have now become practically uniform throughout the old country, we will be able to supply the kind of gas that Mr. Weber has outlined but for the present purposes those of us who must meet a standard of sixteen candle power which means at least 600 B. T. U.'s it is practically an impossibility to supply even 15 per cent of gas having a B. T. U. value of about 308 and mixing it with standard coal gas. If there is anything this association can do or anything any association can do to get the standard fixed approximately at what the English standard is they will have done the gas fraternity more good than anything that has been done within 25 years. That is firmly my belief. After a great deal of experimenting and following results closely Sir George Livessey gave the last days of his life in a determined effort to get this standard fixed in England and he finally succeeded. fought this question for five years before various Parliamentary committees and it was settled finally, so that the London companies today are not subject to a penalty if they do not fall below 426 B. T. U.'s net. That means about 14 candles, tested by Metropolitan No. 2 Burner.

He

The President: Gentlemen, we have three other papers to read and some other business to transact and if it is agreeable I would suggest that we postpone discussion on Mr. Weber's paper for the present and go on with these other papers and then we can resume the discussion afterwards and accommodate ourselves to the time that we may have to spare

THE ELECTRICAL SEPARATION OF TAR

FROM COAL GAS.

By

Alfred H. White, John W. Hacker* and Frank Steere.

The questions of the proper rate of condensation of coal gas, the proper temperature at which the suspended tar globules should be separted, and the proper point in the process at which the gas should be first scrubbed with water have formed the subjects of many papers presented at gas associations. Practical considerations have, however, limited very much the possible scope of experiments on these points, for the only feasible means of removing the suspended tar particles has been by frictional separators or by scrubbing, which operations can only be carried on effectively after the gas has been cooled. The question whether it would be better to remove tar from the gas while it is still hot, although it has been debated warmly, has been largely discussed from a theoretical standpoint.

Our attention was directed to the possible applications of the silent electric discharge to the purification of illuminating gas by the brilliant paper of Dr. F. G. Cottrell on "The Electric Precipitation of Suspended Particles", which appeared in the Journal of Industrial and Engineering Chemistry for August, 1911. In this paper Dr. Cottrell reviewed the work of earlier experimenters and showed the successive steps of the development of his process up to the point of successful installation of a plant precipitating the objectionable fumes from a giant smelter or the dust from a rotary kiln of a Portland cement plant.

*Holder of the Michigan Gas Association Fellowship at the University of Michigan for the year 1911-12.

This process claimed our attention not only because it offered an opportunity for experimental work in a way hitherto unattempted but also because it afforded at least a possibility of commercial application. Dr. Cottrell's figures on the amount of electric power consumed by the process were startingly small, only 120 kilowatts being required to remove the suspended particles from a volume of gas requiring a flue with a cross section 18 by 20 feet for its passage and amounting to between 200,000 and 300,000 cubic feet per minute. This remarkable showing prompted us to consider whether the same process might not be applied to the elimination of suspended tar and liquor particles from illuminating gas and experiments were at once started to determine this point. It has been possible to make only a beginning of the solution of the problem, but enough has been accomplished to show that the process offers much promise of commercial success. This paper describes the general principles of the process and gives some account of the experimental work carried on at the Gas Experiment Station of the Michigan Gas Assocation and in the laboratories of the University of Michigan.

The disappearance of dust clouds under the action of an electric discharge was observed many years ago, but the credit of independently rediscovering the fact and bringing it to the attention of the public is due to Sir Oliver Lodge who, in 1886, delivered an illustrated lecture on the subject of the electrical deposition of dust and smoke before the Liverpool Section of the Society of Chemical Industry. His experiments had been previously brought to the attention of Mr. Alfred Walker who, after experimenting on the small scale at his Bagillt Smelter installed a full-sized equipment to treat all the fumes from this plant. The only source of high-tension current available in those days was the static machine and this plant was to be operated by two Winshurst machines with five foot discs, driven by a small steam engine. No record seems to have been published of the success of this project, but its failure is probably to be ascribed to the uncertainty of operation of the electric generator. Dr. Walker took out U. S. Patent 342548 in 1886, a part of whose claim reads "consisting in causing the fume *** to be subjected to a discharge of electricity from an insulated conductor