At temperatures below 1000, the agreement in Table IX between theory and practice is close if the rate of flow of the gas is slow, or if the gas encounters sufficient deposition surface. Thus, in a test from 45° to 360 on a large volume (70 million cubic feet) of gas, the collected condensed water and light tar-oil together agreed exactly with the weight for water only, as given in Table IX. But if the flow of gas is fast, and if the tar and water are not then removed by scrubbing or filtering, the temperature of the gas will fall while it still carries along the condensed entrained water and tar. For the purposes of design of apparatus and manufacture of gas, Table IX is sufficiently accurate to be of practical application. For example, from Table IX it can be deduced that, in general, cooling water-gas by air is not economically practicable. In 1900, at the Bay State Works, a test was made on cooling carburetted watergas from 180° to 1720, using 5,000 cubic feet air per minute. The heat lost by the gas and the heat absorbed by the air were in satisfactory agreement, and both amounts agreed with the heat as calculated prior to the test, from the data in Table IX. It was found that cooling by air gave no promise of economy, under the existing circumstances of manufacture.

Where no provision is made for repeated circulation of the water as supplied to the wash-box, it is evident that there will at once be set up a heavy flow, ranging in amount from 11 to 7 gallons per 1,000 cubic feet of gas made (11 gallons when running high heats and using hot water in the wash-box, 7 gallons when running low heats and using cold water in the wash-box). This must flow through the tar-well, and thence into some convenient sewer, river or bay. I have observed one drop of tar and lampblack spread evenly and without a break over 100 square feet of water surface. Thus an uninterrupted overflow from the tar-well may carry away to loss valuable tar, and may contribute cause for complaint.

When the tar and water have been separated from the gas, when the water has been separated from the tar, and when the tar has been sold, or profitably used, this residual should figure in the record of enriching effect of the oil used. If 5 gallons of oil per 1,000 give 30 candle power gas, and if there is a residual of one gallon of tar per 1,000, then

the gross efficiency of the oil is 30-5-6 candles per gallon; the net efficiency of the oil is 30-4=7.5 candles per gallon.

Four gallons of the original enricher remain in the gas and give the measured illumination. Any complete statement of carburetted water-gas should include not only the candle power of the gas, and the kind and amount of oil used, but also the amount of clear tar recovered. The best net efficiency per gallon of oil, at Bay State Works, has been

for gas oil, 7.29 candles per gallon.

for naphtha, 6.72 candles per gallon.

It is always to be expected that laboratory facts will not agree exactly with factory facts. President Charles W. Elliot, of Harvard University, in an address at the Brooklyn Institute of Arts, said, "Any one who desires to attain to the capacity for exact observation and exact description, and knows what it is to draw a correct inference from well determined premises....has learned how hard it is to determine a fact, and to state it accurately."

In this, and in succeeding notes, all references are to the American Gas-Light Journal, by date and by page, unless otherwise stated.

Analysis of three samples of crude petroleum.

-DURAND WOODMAN.

-DAVID DOUGLAS.

The manipulation of tar from carburetted water-gas.
A. G. L. A.

Petroleum products,-hydro carbon employed in gas man-
ufacture. W. G. A.
-C. M. HIGGINS.

In a paper on "Enriching Coal-Gas," is an analysis of

-J. MACKAY.

-J. M. RUSBY.

In a paper on "Naphthalene," is a sketch of a still now

sometimes used on oil-tar.

1901, Sept. 9. Vol. 75, P. 405.

Practical testing of oils for gas and fuel purposes.
P. C. G. A.

-L. P. Lowe.

In "Proceedings of American Gas Light Association," Vol. XV, pp. 69 and 70, there is description of apparatus for separating water from oil tar.

{

We are getting some 6 cents per gallon for water-gas tar, where using crude Lima oil. -F. H. SHELTON.

Some of it was worked up by simple treatment into an excellent varnish for painting and preserving, selling for $10 per barrel. In several places that I know of 6 to 9 cents a gallon is a current price paid for water-gas tar with water eliminated. O. G. L. A.

-F. H. SHELTON. Oil-tar is now turned over to chemical works and tar distillers at a price invariably in excess of the cost of an equal quantity of the original oil, and in some localities at double this cost. -A. G. GLASGOW. Distillers buy tar with 20% water in it, and pay a price almost as great as coal-tar is selling for in the immediate neighborhood. A. G. L. A. -ALTEN S. MILLER. Oil-gas tar or water-gas tar is really more valuable, when once separated, than is coal-gas tar. N. E. A. G. E. -A. C. HUMPHREYS. The tar from water-gas is unquestionably for many purposes of better quality than coal-tar. N. E. A. G. E. -A. C. HUMPHREYS. In Wilmington, Delaware, tar from oil-gas, (free from water,) is sold at as good a price as coal-tar. W. G. A. -F. EGNER.

Must regard tar made from use of crude oil as a residual
worth from 4 to 10 cents per gallon. W. G. A.
-A. C. HUMPHREYS.
Cannot get 4 cents per gallon for tar from crude-oil. Am
offered 2.5 cents per gallon for tar from naphtha. W.
G. A.
-C. R. FABEN.

Tar with less than 8% water can sell for about 70 cents per
barrel. A. G. L. A., Question 5.-W. R. ADDICKS.
Coal-tar should be worth two or three times more than
oil-tar.
-EDITORIAL.

2.5 barrels tar equal one ton coal, as fuel. A. G. L. A.
-W. H. PEARSON, JR.

Worth 1.75 cents per gallon in New York City. Worth
for fuel, 1.125 cents per gallon in New York City. A.
G. L. A.
-ALTEN S. MILLER.

7 cents per gallon at Key West.

Worth more than 2 cents per gallon
Gas Works. N. E. A. G. E.

"TRAVELLER."

as fuel at Bay State -W. E. MCKAY.

NOTE C. TABLE I.

GAS MADE IN MASSACHUSETTS (YEARS END JUNE 30).

1898

1894

1893

1892

1,759,332,000 36 3,166,847,000 64 8,247,000 1897 1,654,454,000 35 3,079,843,000 65 1896 1,767,591,000 38 2,875,566,000 62 1895 1,532,989,000 39 2,413,266,000 61 1,544,787,000 43 2,021,897,000 57 2,110,538,000 59 1,466,757,000 4I 15,589,000 3,592,884,000 2,326,472,000 65 1,230,816,000 35

4,934,426,000

10,965,000

4,745,262,000

14,519,000
12,518,000 3,958,773,000
13,100,000

4,657,676,000

3,579,784,000

13,600,000 3,570,888,000 777,005,000 13,053,000 3,435,919,000 209,819,000 6 12,476,000

3,360,415,000

75,696,000 3 11,600,000

3,188,496,000

1900

In 1900, the gas of the Massachusets Pipe Line Company has not been included, because the corresponding residuals are not returned in the Report of the Board of Gas Commissioners. Adding the 664,147,000 made (bought) by the Massachusetts Pipe Line Company, figures of the components and total for the year 1900 become