load could, in fact, be safely carried with either producer working singly. Fuel containing as much as 70 prr cent. of water has been used and the plant worked w l f . The separation of tar from the gas has been the chief difficulty to overcome. I t lias been found to be better to rely on watcf sprays than coke scrubbers, for the latter rapidly clogged. The main portion of the tar is thrown out into a tar sump by a centrifugal extractor, but unless the gases arc subjected to a thorough washing and cooling i t has been found thai certain portions get past into the gasengines. The precise amount of water necessary has bccn determined for the cooler to ensure condensation of the tar.vapor beforc reaching the extractor, and thus the amount of tar in the gas a t the engines is small and thc valves require cleaning only once a week. At first, the plant and producers required thorough cleaning once a week, but a t present they can be run for three weeks. The washing water is now 7 gallons pcr B. 1%.P. hr. The cost of running the factory on coal was about $xjj.oo per week, compared with $80.00 oil peat, not allowing for extra labor. The peat has the fullowing average composition: Carbon, 24.75 per cent.; volatile matter, 5 j . 1 ; per cent.; water, 18.98 per cent.; and ash, L I O per cent. The gas resulting therefrom has a calorific value of I & 3 . t. "..per cubic foot. Apparently by-product producers are not used, for no mention is made of ammonium sulphatc recovery.
A NEW WATER-JET AIR-PUMP. The water-jct air-pump illu,trated herewith, of German manufactt\re, is intendcd for iise in operating siphons, centrif-
secondary air system supplying prehrated air over and beyond the fuel bed. The priniary air is obtained from an cngincdriven blo~ver,the exhaust from tlie cngine of which is utilized in the ash~pit. This air is introduced a t a pressure just sufficient to force it through ihc fuel. The draft over the fuel is generally maintained a t 0.1-0.13 inch water gauge. The quantity of secondary air is regulated a t lhe stack damper and the damper in the supply pipe. This air is preheated in flowing between iwo firebrick arches of the furnace. .
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REINFORCED GALVAAIZED SPIRAL PIPE. There has been placed on the market a reinforced galvanized spiral pipe which is made from two strips of steel of different widths and with a continuous interlocking seam. Both strips of steel are rolled to shape on lhe edges and are interlocked and rolled down under very high pressure in a special machine which has been patented by the pipe manufacturers The strips of steel are first cut to the required width from long sheets of steel and the ends are welded together. The steel is then placed on large spools. The strip used for the outsidt or reinforcing band comes from the steel mills in long lengths on reels. Both of these strips are fed into the machine a t one end, rolled down interlocked in ihe machine, coming out a t the other end in the shape of pipe. The pipe is smooth on the inside and has the reinforcing band running on the outside the entire length of the pipe; it can be made endless. A NEW AUTOMATIC WATER-JET AIR-PUMP. The pump illustrated in the accompanying diagmn is capable of producing a vacuum of about 9 meters a t a working pressure of 10 mcters. The air-chamber cares lor the air which is brought up by the muvement of the water in the pipes. I t is possible by means of observations through a transparent glass to ascertain whether the content of Lhc air chamber is water or air.
A.-.4ir
B.--Gius r tion. A.-Air chamber. H.--Siphohon arrangement. I,,, Lz.--Water jet "ir-""'"P.
D.-Wiiter E i i p ~ l ~ S.--Suctian 01 the p u r n ~ .
chamber. far ubsrrus-
c
C.-Water exhaust. D.-Water D ~ ~ S E I con. Y ~ nection. H.--Syphun connection I-.-Air-~urn~.
V.--Exhaust valve.
ugal pumps, pulsometers, for exhausting the air from vacuum chambers, etc.
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THE PARKINSON PATENT FURNACE. With many grades of fuel, especially those of the lignite variety where moisture, volatile matter and ash are high, it is difficult to obtain efficient combustion. The Parkinson patent furnace, described in Power, 36, 367, is especially dcsigncd for use with low-giade fuels. This furnace lias five dislinclive features: a large ash-pit which closes air-tight; individual rocking water-cooled grates; a deep firebox accommodaiing a fuel bed 14-24 inches deep; a primary air system supplying air to the ash-pit under the fuel bed together with the required moisture, usually in the form of exhaust steam from the fan engine; and a
1
j. In the evacuation of ccntrifugal pumps the exhaust-pipe must be provided wilh an air-tight protection in order to permit of the formation of a vacuum throughout the air-pump. To operate the pump, the water iq admitted first, and then the air; in order to stop it, the reverse is donr. In operating the pump under a pressure of about zo meters, the connecting-pipes must^ be placed a few centimeters under water.
