INDUSTRIAL AND ENGINEERING CHEMISTRY
February, 1923
experiments he worked in the region of 90 per cent or less undecomposed water, whereas our Iampblack-carbon runs were at 50 per cent or less undecomposed water.
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O Q
UPPERCURVE,1128-Mu.PRESSURE LOWERCURVE,363-Maa. PRESSURE
PRACTICAL ASPECT Aside from the light thrown on the mechanism of watergas formation, there are also practical results from the investigation. Inspection of Plate 5 shows that a threefold increase in pressure produced almost a threefold decompo-
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sition of water, and that the composition of the resultant gas corresponds to that formed at equivaIent water decomposition a t a low pressure. This increased rate of decomposition of water is also shown in Plate 8 where the pounds of water decomposed is plotted against temperature from the low- and high-pressure runs of Series 11. Increase in pressure, therefore, affords an excellent means for increasing the capacity of a given sized water-gas generator. For example, if a generator is operating at atmospheric pressure, its capacity can be increased almost fourfold by operating at 70 Ibs. per sq. in. gage, and the composition of resultant gas will remain as formerly. I n other words, increased pressure gives approximately the same effect as an increased time of contact. Again, it is almost impossible to increase the thickness of a water-gas generator fuel bed owing to the increase in CO during the air blow. Increase in the pressure will permit the decrease in the thickness of a fuel bed if increased capacity is not desired, thus resulting in a lower CO content in the blow gases. An increase in the pressure may be used to prolong the duration of a steam blow, or may be used to operate a t a reduced temperature of the fuel bed where such is desirable. Still again, one of the difficulties in the use of bituminous coal as a water-gas generator fuel lies in the smaller amount of surface when the coke is produced in the generator as compared with the surface of the usual coke as charged. ?Increased pressure may be used to compensate this decrease in surfaces, thus removing one of the obstacles to the wider use of bituminous coals in watergas production. Many other advantages of increased pressure no doubt suggest themselves. Incidentally the results of this work permit a more quantitative study of producer gas, as will be shown in another paper.
A Constant-Temperature Oven’
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By Colin M. Mackall, G. E. Miller, and E. Emmet Reid CHEMICAL LABORATORY,
JOHNS
HOPKINSUNIVERSITY,
HE OVEN here described is built on the same principle as several that are illustrated in laboratory manuals and catalogs of apparatus dealers2 but embodies some improvements which add to its usefulness. The drawing represents a longitudinal section. The oven serves well as a drying oven, with or without vacuum, and also for heating substances at constant temperature in a current of any desired gas. If it is desired to use a current of gas, the stopper C is replaced by a stopper carrying two tubes, one of which passes through the upper part of the stopper and extends over the boats t o the back end of the chamber and the other ends just inside the stopper. The heating chamber AB is a glass tube 3.5 X 50 cm. closed a t one end and carrying a ground-in stopper, C, at the other, through which it may be evacuated, etc. A suitable liquid is boiled in the flask H, the vapor ascending through the head J and the tube K and passing through the annular space within the fused-on jacket surrounding the heating chamber and escaping by the downward sloping tube E. The vapor is condensed in P and returned into the flask H through the trap G, which serves also as an expansion coil. The vppor
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1
Received December 1, 1922.
a “Handbuch der Biochemischen Arbeitsmethoden,” Vol. 1, p. 296.
Abderhalden.
Berlin, 1910.
BALTIMORE,
MD.
which condenses in the heating jacket drains into the return tube at F. The flask H may be ground onto the head J or connected by a mercury seal, as shown at N. The oven is insulated by a thick 85 per cent magnesia jacket, ST. A s m a 11, low-voltage electric light a t Q controlled by a switch at R serves to illuminate the h e a t i n g chamber. so that it is easy’ to see the boats U, and re0 move them without spilling. The furnace is supported by the wooden frame LM. To obtain differe n t temperatures, liquids of different boiling points are used in &e flask, toluene being the most desirable for general purposes. If a more volatile liquid is used, a correspondingly more efficient condenser must be substituted for the type shown in the drawing.
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