minute at a pressure of 11⁄2 ounces, and runs at 3,400 revolutions per minute. Six-inch galvanized iron piping is run along the top of the benches with 4-inch branches down the center to the level of the middle retorts. Here we use a thimble cap when not in use, and flexible ells to make the connections when scurfing. For the pipe inside the retorts, old boiler tubes 22 or 3 inches in diameter are used, as these burn up in about 2 scurfings.

With fair heats, retorts quite heavily carboned are scurfed in from 6 to 8 hours, and in a slightly longer time with lower heats. This before the retorts or joints open up; and in comparatively short time when the works are taxed with large send outs. The cost of the outfit, including fan, motor and pipe for 4 benches, was about $90, and when an electric plant is run in connection with the works the cost of operation is practically nothing-200 watts per

hour.

No. 7.-Device for Cleaning Service Pipes.-Mr. C. H. Nutting, Chicopee, Mass., kindly contributes the following: I have in our office a 5-horse power gas engine, connected for show purposes. This engine has a self-starting arrangement, consiting of an air tank of about 10 gallons capacity, and when pumped ready to start the engine, contains 80 pounds pressure.

Frequently I would find that the men had disconnected this tank and used the contents to blow out a service, and when I wanted to show the engine to someone there would be no air to start it with.

I then bought a 10-gallon tank and a hand air pump, the outfit costing $17-and now when a service needs to be blown out, the men always carry this tank, and I find it gives thorough satisfaction. It takes 5 minutes to pump this tank up to 50 pounds, and 10 minutes to pump up to 80 pounds pressure.

No. 8.-Testing Plant for Coal Gas.-Mr. W. A. Baehr, Denver, Colo., says: In one corner of our retort house cellar we erected a corrugated iron shed, and in it put a small Roots exhauster, a hot washer, pipe condenser, ammonia scrubber, purifier and small station meter.

The exhauster has a 2-inch bye-pass with a stopcock in it, and since it is driven by an electric motor we secure the proper regulation by means of the stopcock in the bye-pass. This plant is of such a size that it readily handles all the gas made in one of our regular retorts. After passing the station meter the gas is conducted to either a photometer or back into the regular foul

The object in using one of our regular retorts is to secure working conditions. In this plant we have tested 20 to 30 different kinds of coal, securing the following data for each kind:

I. Gas made; 2, coke made; 3, tar made; 4, ammonia made; 5, complete gas analysis; 6, candle power.

We will say, from our experience with this plant in Denver, that we have found it very useful and would not be without it. No. 9.-Wrinkle in Operating Water Gas Plant.-Mr. W. A. Baehr, Denver, Col., on the matter of water gas economy, writes: We find quite a saving in the operation of our water gas plant by opening the blast valve on the generators at the end of the run before opening the stack valve.

When the run is over the operator opens the generator blast valve, walks to the steam valve and shuts that, and then walks to the stack valve lever and pulls it open. It averages 12 to 15 seconds from the time of opening the generator blast to opening the stack valve. During this time most of the remaining gas in the carburetor and superheater is driven past the seal by the blast, thus saving what would otherwise be lost.

No. 10. Conveying Coal by Hanging Railway. By the Editor.-In some works where the coal storage is quite a distance from the retort house the hanging railway and car shown are found advantageous for bringing the coal to the front of the stack. The car tips sideways and is easily pushed by hand.

No. 11. Drip Pot.-By the Editor.This drip is of advantage in reconstructions, as the slight fall in the level of the tar and ammonia liquor is often greatly desired to give sufficient drop to the wells. The tar and ammonia enter by the 3-inch connection, and, after passing down and under the seal, run to the cisterns from the 4-inch opening. The other three hand-plate openings are for cleaning.

WRINKLE No. 10.

No. 12. Compact Station Meter Connections. By the Editor. This arrangement, consisting of 3 angle valves, cuts the cost of piping by two ells and one T, and proves a great saving in cellar space. The drawing is self-explanatory.