COMMUNICATIONS TO THE EDITOR
Jan. 20, 1953
499
THE TEMPERATURE OF THE CYANOGEN-OXYGEN FLAME Sir :
oxygen the flame consisted of two zones; the inner zone was a brilliant white comparable to that of a carbon arc. The outer zone had the blue color We have recently determined’ the temperature characteristic of the carbon monoxide flame in of the HrFz flame to be 4300 150’K. a t 1 atm. oxygen. In this work the outer zone was about 1” pressure, using a modified line-reversal technique, long and the inner zone l/4” to l / g “ in length. These with the sun in the heavens as the comparison ra- dimensions correspond to a total gas rate of about 200 cc. per minute. In these instances the flame diator. A much higher flame temperature is to be ex- burned right a t the tip of the torch. pected from thermodynamic considerations for The theoretical flame temperature as a function of the cyanogen-oxygen flame, according to the reac- inlet gas composition was calculated using the tion latest thermodynamic data7~8~9~10,11 (AGfor (CN)2dissociation = 114 kcal./mole) .lo These results ( C W ? k ) Oz(g) --+ 2CO(g) W g ) with the experimentally determined flame This reaction is exothermic to the extent of 126,680 together temperatures for various gas compositions are given cal. a t 298OK. Furthermore, the thermal stability of the CO and Nz molecules is even greater than in Table I. TABLE I that of the HF molecule. Experimental Theoretical Although the (CN)2-0~flame was studied many temp., temp., O K . Vol. %, Os, (CN): years ago,2,8its flame temperature bashever been 25.3,74.7 2580,2640 .. measured directly. This year Thomas, Gaydon 26.8,73.2 3090,3120 .. and Brewer4 measured the vibrational “tempera33.3,66.7 3270 3200 ture” of the flame molecules and obtained a “tem36.5,63.5 3333 .. perature” of 4800 200’K. a t the stoichiometric 50.0,50.0 4640 4810 composition. The calculated flame temperature 62.0,38.0 4453 .. reported by these authors was 4850 i 30°K., 66.7,33.3 4003,4043,4073,4143 3700 using the high value, Le., A# = 226,000 cal./mole The maximum experimental flame temperature or 9.76 ev., for the dissociation energy of Nz. They pointed out that by using the lower dissocia- was observed a t the stoichiometric point (30 vol. tion energy, Le., = 170,240 cal./mole or 7.38 % (CN),) in line with the above equation and eyuals ev., the calculated flame temperature was 4325’K., 4640O f 150’K. Thus at one atmosphere total thus fixing the dissociation energy of Nz at 9.76 pressure it is 340’K. higher than the hydrogenev. However, the vibrational “temperature” is fluorine flame and is therefore the highest directly not considered sufficiently representative of the measured flame temperature recorded to date. The theoretical flame temperature for the stoitrue thermodynamic temperature of the flame. chiometric composition is calculated to be 4810 This conclusion was reached in connection with our work on the HTFZ flame. The vibrational “tem- f 50’K. using the high value for the dissociation perature” of this flame was measured in our labora- energy of nitrogen. A temperature of 4375OK. tory by Drs. W. S. Benedict, S. Silverman and was obtained using the low value. The experiB. W. BullocP of the National Bureau of Stan- mental flame temperature is in good agreement dards and it was found t h a t the precision and with the higher theoretical flame temperature and reliability of direct flame measurements by the line- as such represents the first direct measurement of reversal method was greater than that of ,vibra- the cyanogen-oxygen flame temperature. (7) 0. P . Stevenson, J. Chcm. Phrs., 7, 171 (1939). tional “temperature” measurements. (8) H. M. Spencer and G . N. Flannagan, THISJOURNAL, 64, 2611 Our modified line-reversal method’ was again employed. The metered (CN)Z6 and 0 2 streams (1942). (9) J. W. Knowlton and E. J. Prosen, J . Res. 3 - d . Blrr. Stds., 46, were premixed in a 6-mm. glass tee filled with 20- No. 6, 489 (1951). (10) L. Brewer, L. R. Templeton and F. A. Jenkins, THIS JOURNAL, mesh quartz chips. A short length of quartz tubing acted as a torch tip. This tip was also 73, 1462 (1951). (11) National Bureau of Standards, Selected Values of Thermofilled with quartz chips and attached to the free dynamic Properties, API Project p44. end of the premixing tee by means of a piece of THE RESEARCH INSTITUTE OF J. B. CONWAY rubber tubing. The small oval-shaped opening in TEMPLEUNIVERSITY R. H. WILSON,J R . * the face of the quartz torch tip measured 0.134” PHILADELPHIA, PA. A. V. GROSSE X 0.031”. Small needle valves in the inlet gas lines RECEIVED OCTOBER 20, 1952 made it possible to vary the rate of either gas. The shape and structure of the flame varied with feed gas composition. Near the composition AMICETIN, A NEW STREPTOMYCES ANTIBIOTIC corresponding to one mole of cyanogen per mole of Sir: (1) R . H. Wilson, Jr., J. B. Conway. A. Engelbrecht and A. V. A Streptomyces sp., isolated from a soil sample Grosse, Tms JOURNAL, 78, 5514 (1951). collected near Kalamazoo, Michigan, was found t o ( 2 ) H. Dixon, J. Chem. SOC.(London), 49, 384 (1886). inhibit a number of bacteria when grown on an (3) A. Reis, Z. physik. Chem., 88, 513 (1914). agar streak plate. Mycobacterium tuberculosis var. (4) N. Thomas, A. G. Gaydon and L. Brewer, J . Chem. Phys., 20, 369 (1952). hominis (ATCC 607), Proteus vulgaris, Escherichia ( 5 ) See W. S. Benedict, B. W. Bullock, S. Silverman and A. V. coli, and Staphylococcvs aureus were markedly inGrosse, Phrs. K e u . , 87, 213-214 (1952). hibited when cross-streaked against this new iso(6) (CN)r was prepared by thermal decomposition of Ag(CN), coupled with stnndard purification. late. When the organism was grown in submerged
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