M. Witz, says the Gas World, has been conducting a series of experiments on the Delamare-Deboutteville and Malindin gas engine, driven by Dowson gas, and in which the gas generator takes the place of the ordinary steam boiler.  The engine was a one-cylinder motor in the establishment of Messrs. Matter & Co., Rouen.  Its power was 100 horse indicated; the cylinder was 23 inches in diameter, the stroke 38 inches, and the normal speed 100 revolutions.  The engine is of the Simplex type; the kindling is electric; the cycle of operations is fourfold, with powerful compression.  The Dowson generator is 30 inches inside diameter and 76 inches in height from the bars to the top.  Air is blown in by steam driven in under the hearth.  There is a siphon, a coke scrubber 110 inches high, a sawdust purifier, and a gasholder of 750 cubic feet capacity, and a pipe to the engine 5.2 inches in diameter.  The total area occupied by this apparatus is 140 square yards, of which two-thirds are built on.  The anthracite employed was from Swansea, containing 5.4 per cent. of ash.  The observations made with a string friction brake were continued for 68 hours, everything used being carefully weighed and measured.  One day the machine was worked for 151/4 hours on end; the other days it was worked with an interval of half an hour every 12 hours to clear the hearth, poke the fire and lubricate the machine; and it was clearly established that with a big enough generator it would be quite possible to work continuously for several days.

The following were the data for a day of 24 hours, with an interval of half an hour:  8:55 P.M. one day to 8:55 P.M. the next, interval 8:30 to 9 A.M.  Anthracite used, 18.4 cwt.; coke used, 3.42 cwt.; water used for steam injection, 217.3 gallons; water used in scrubber, 4,106 gallons; water used in cooling the cylinder, 20,000 gallons; oil used in cylinder, 14.84 pounds; grease, 1.8 pounds; revolutions of machine, 142,157, or 100.8 per minute; effective work, 75.86 French horse power, or 77.4 British; gas used, 6,742 cubic feet per hour, at 772 mm. pressure and 70.7 deg.  F., or 83.7 cubic feet per effective horse power; efficiency, 69 per cent.

Now, with regard to the comparison between the large gas motors and steam engines of the same size, M. Witz goes on to remark that the gas engine is by no means, as was formerly thought on high authority, necessarily restricted to the domain of smaller work and sizes.  Even in early times it was seen that the gas engine belonged to a type in which there were possibilities of improvement greater than those available in the steam engine, because the difference of temperature between the working substance in its hotter and its cooler condition was greater than in the steam engine; and consumptions of 5,250 cubic feet per horse power per hour soon descended step by step as far as 2,060, while the power went up, past 4, 8 and 12, to 25 or 50 horse power; and in the exhibition of 1889 there were gas engines seen in which the explosion chamber had a diameter of as much as 23 inches.