INDUSTRIAL AND ENGINEERING CHEMISTRY
752
is applicable to the estimation of even the smallest amounts of methanol. Using 5 per cent ethyl alcohol solution, the standards recommended for comparisons are: 0.00, 0.01, 0.05, 0.1, 0.2, and 0.4per cent of methanol. It is quite (1) necessary that standard conditions prevail-namely, 5 per cent alcohol; (2) the same kind and amount of reagents; (3) 10 minutes for oxidation with potassium permanganate; (4) uniform temperature (room temperature is satisfactory,
Vol. 19, No. 6
since both samples and standards will be a t whatever temperature prevails); (5) length of time (20 minutes) in making comparisons after the addition of the modified Schiff reagent. Acknowledgment The writer is indebted to John F. Williams of this laboratory and t o E. Raymond Riegel of the University of Buffalo for advice and assistance.
Flat Luminous Flames' By D. S. Chamberlin and W. E. Thrun2 LEHIGHUNIVBRSITY, BWIHLEHEM, PA.
A formula has been adapted f r o m the Poiseuille A n o r d i n a r y differential I T T L E has been ref l o w m e t e r was constructed equation for the flow of gases through a narrow slit corded concerning the as exhibited in the lava tip. A comparison Of t h t flow with a pressure gage attached burning of combustible gases in secondary air from as shown in ~i~~~ 2. of different gases f r o m such tips in an ignited and an unignited condition detelops various factors that are slotted tips. Several investistudied in this paper. The arms of the meter were g a t o r ~have ~ ~ ~made , ~ investiThe shape and size of the lava-tipped flame was kept Parallel by two Or three gations on the various types of luminous flames a s t h e y studied by photographic methods. The differences in gas flow f r o m the tips in ignited and unignited conthe burn from lava tips in the was controlled by a ditions are discussed. It was found that the wider b o l t t h a t could be screwed shape of fishtails, batwings, vertically through a nut. The slotted tips did not conform to the same principles as etc., but such data on the nut being soldered to the gage those of narrower slotted tips. shape and size of flames, flow holder, a slight motion of the rates, temperatures, and presbolt quickly adjusted the levels sures that can be applied t o the laws for the flow of gases to the desired zero. At high rates of gas flow a movement of 1.0 cm. corresDonded to a change in gas flow of 0.03 liter Der minute: are rather incomplete. a t the lower rates of flow i.0 cm. movement corresponded to a I n the fundamental study of flat luminous flames, account change in flow of 0.68 liter per minute, must be taken of the size and shape of tip used. Lava Pressure-Rate Relations tips as employed in the older methods of gas lighting were The data given in Table I were taken from a number of series of experiments that were performed under constant conditions. The gas escaping through a tip was lighted and the flow rate adjusted for a definite flowmeter reading. The pressure was then read. The flame was then blown out I and the gas allowed to escape into the room. ilfter a 3minute interval the pressure and flow rate were again observed. On igniting the gas the initial readings were checked. These data were plotted and the results showed that:
L
yEkie,I"dti^^^
7-1I
I I I
Section through slot Figure 1-Lava
I
Side view Tip
1-The pressure-rate curves were not straight lines. \Then the gas was burning, the curve approached a straight line more nearly than when the jet was unignited. 2-The difference in pressure of burning and unignited jets rose with increasing flow rates to a maximum and then receded. It receded approximately to a zero value, as was found in several other runs. These runs are not shown.
used in the determinations described herein. They are made of steatite, a magnesium silicate. In the green state steatite is soft and therefore can be made into any desired form by turning, milling, and grinding. The tips are then fired to a temperature of about 1400" C. Figure 1 shows the construction of a typical lava tip. Gas and Apparatus Used
Natural gas with an analysis of 71.2 CHI, 23.3 CzHt,, 4.7 NZ,and 0.8 per cent COSwas used in this work. This gas was delivered a t a uniform pressure from a gas holder. 1
Received January 4, 1926; revised manuscript received March 23,
1927.
* Columbian 4
6
Carbon Fellow, Lehigh University. Matake Kurokawa, J . SOC.Chem. I n d . ( J a Q a n ) , a@, 139 (1926). Ring. "Treatise on Gas." Bur. Mines, Bull. 192.
f Figure 2-Flowmeter
w i t h Pressure Gage
In the investigation of the factors that controlled these flames, it was found quite generally that there was a maximum point in the flicker of the flame,6its shape, and tempera6
Chamherlin and Thrun, Gas Age-Record, 57, 41, 52 (1926).
t,ort~. In order to explain this apparent, "back pressure" on unigrlited jets, an equation which holds for the flow llf gases through circular orifices wmadapted to lava-tipped jets. The eniiation' KoRz h=-
a6
as srliipted from the formnla of Poi s e u l k arldled to tbp flow of gas tlrrough cirrrilar orifices Thib iorniula criuld
:--Let Wt = the standard tip width, W, the wide tip width, PI = ( k - h'j for W,, and Pa = ( h - h'j for W, Since W,/W, = 060, then P,/P, = 000 The fncrease in pressure IS m r e r r e ~ yproportional to the slit wldth 0 -For all narrow slotted tips there IS a mamnum value ior the difference m preswre between the burning and nmpnited tips This maximum difference, h - h', occurc at the gas-flow rate oi 1 2 hterc per minute
Effect of Temperatures on Value ( h - k ' )
Wlien the let was burning, the gas was not rnrnsurerl at the temperature at which I t evaped irom the tip but a t a lower temperature. The tip becomes heated and some of l b e beat IS absorbed within the tip by the gas In the equation p would h a w a value too large and R a value too srriall. Let T be tlie absolute temperature oi the gas as measured and T - t the temperature oi the gab a5 it escape-. Th'n k , = K __ T (K or
w)',
T + t
Fie"'* 3
h,
PifWP 4
be applirxl to tbe narrow slit, opening by droppilig the it' (dianiett.r) and including t , l k slit-opening factor in t,lIc tern, K . \%:bereh is tlic pressure in millimeters of waher, p the dmsity of tlie gas in grams per liter, and R the rnte of ga,s fl
