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Distribution of energy in the visible spectrum of an acetylene flame
June, 1916.1
U.S.
BUREAU
OF S T A N D A R D S N O T E S .
849
8. In an oxidizing atmosphere at temperatures of the order of I000 ° C. platinum, in the presence of, but not in contact with, silica, will apparently take up small quantities of this substance. 9. The loss in crucible weight due to the solution of soluble matter in HC1, after heating, is variable, depending on the crucible, and may be large. This loss is relatively greater at low than at high temperatures. I0. All of the above losses, caused by heating, acid treatment, and iron diffusion, apparently continue with undiminished magnitude after the first treatment, which is usually erratic. II. The following table gives the approximate changes in weight to be expected for heating platinum containing iridium or rhodium, but nearly free from iron. The presence of iron in appreciable quantities renders the prediction uncertain, but it always acts in the direction of lowering the volatilization loss. Silica, if taken up from the furnace, will also tend to lower the results slightly. Approximate loss in m g . / I o o em.2/hour at temperatures indicated for platinum nearly free from iron. Platinum containing Pure Pt 900 or l e s s . . o IOOO . . . . . . . . 0.08 12oo . . . . . . . . o.81
DISTRIBUTION
x per cent. Ir 2.5 per cent Ir 8 per cent. Rh o o o 0.30 0.57 0.07 1.2 2.5 0.54
OF ENERGY
IN THE
AN ACETYLENE
VISIBLE
SPECTRUM
OF
FLAME.*
B y W . W . C o b l e n t z a n d W . B. Emerson.
DATA on the distribution of energy in the visible spectrum of a standard source of light are frequently needed in connection with investigations in physiology, in psychology, and in physics; especially in photo-electric work, in photography, and in the photometry of faint light sources. Frequent requests for such data have come to this Bureau. The acetylene flame appears to be a promising source of light, having a high intensity and a white color. The present paper gives data on the distribution of energy in the visible spectrum of a cylindrical acetylene flame, operated under specified conditions. * Scientific P a p e r No. 279.
850
U.S.
BUREAU OF STANDARDS NOTES.
[J. F. [.
In the region of the spectrum extending from the yellow to the violet, the spectral energy distribution of all the flames examined appears to be the same, within the limits of observation. On the other hand, in the region of the spectrum extending from the red 'toward the long wave-lengths the emissivity is greatly affected by variation in thickness of the radiating layer of incandescent particles in the flame. Hence in and beyond the red part of the spectrum the data apply only to cylindrical flames which are operated under specified conditions. F U R T H E R D A T A ON T H E O X I D A T I O N OF A U T O M O B I L E C Y L I N D E R OILS.* By C. E. Waters.
IN continuation of work already published by the Bureau of Standards, as well as in the Journal of I~l~strial and Engineering Chemistry, a study was made of the rate of oxidation of three automobile cylinder oils when exposed to sunlight and air. This was done by determining the increase in weight and in acidity at intervals during a period of 438 hours' exposure. The accompanying changes in the carbonization values were also determined. The general result was that there is a gradual lessening of the rate at which the weight increases, and at the same time the formation of acid and the carbonization value increase more and more rapidly. The Maumene numbers of the oils increased greatly as a result of oxidation, while there was a marked drop in the iodine numbers. After oxidation the oils showed a much greater tendency than before to emulsify when agitated with water. Filtration through animal charcoal removed, to a certain extent, the substances that caused this tendency, and that raised the carbonization values. When the three oils used in the work above, and eight others, were heated to 25 °o C. for periods ranging from one to seven hours, the formation of carbonized matter proceeded at a rapidly increasing rate. The same was true of the eleven oils when heated for three hours at various temperatures from 23 °0 to 280 ° C. It was found that in both cases the greater the carbonization value at first, the more rapidly did it increase as the tempera* Technologic Paper No. 73.
U.S.
BUREAU
OF S T A N D A R D S N O T E S .
849
8. In an oxidizing atmosphere at temperatures of the order of I000 ° C. platinum, in the presence of, but not in contact with, silica, will apparently take up small quantities of this substance. 9. The loss in crucible weight due to the solution of soluble matter in HC1, after heating, is variable, depending on the crucible, and may be large. This loss is relatively greater at low than at high temperatures. I0. All of the above losses, caused by heating, acid treatment, and iron diffusion, apparently continue with undiminished magnitude after the first treatment, which is usually erratic. II. The following table gives the approximate changes in weight to be expected for heating platinum containing iridium or rhodium, but nearly free from iron. The presence of iron in appreciable quantities renders the prediction uncertain, but it always acts in the direction of lowering the volatilization loss. Silica, if taken up from the furnace, will also tend to lower the results slightly. Approximate loss in m g . / I o o em.2/hour at temperatures indicated for platinum nearly free from iron. Platinum containing Pure Pt 900 or l e s s . . o IOOO . . . . . . . . 0.08 12oo . . . . . . . . o.81
DISTRIBUTION
x per cent. Ir 2.5 per cent Ir 8 per cent. Rh o o o 0.30 0.57 0.07 1.2 2.5 0.54
OF ENERGY
IN THE
AN ACETYLENE
VISIBLE
SPECTRUM
OF
FLAME.*
B y W . W . C o b l e n t z a n d W . B. Emerson.
DATA on the distribution of energy in the visible spectrum of a standard source of light are frequently needed in connection with investigations in physiology, in psychology, and in physics; especially in photo-electric work, in photography, and in the photometry of faint light sources. Frequent requests for such data have come to this Bureau. The acetylene flame appears to be a promising source of light, having a high intensity and a white color. The present paper gives data on the distribution of energy in the visible spectrum of a cylindrical acetylene flame, operated under specified conditions. * Scientific P a p e r No. 279.
850
U.S.
BUREAU OF STANDARDS NOTES.
[J. F. [.
In the region of the spectrum extending from the yellow to the violet, the spectral energy distribution of all the flames examined appears to be the same, within the limits of observation. On the other hand, in the region of the spectrum extending from the red 'toward the long wave-lengths the emissivity is greatly affected by variation in thickness of the radiating layer of incandescent particles in the flame. Hence in and beyond the red part of the spectrum the data apply only to cylindrical flames which are operated under specified conditions. F U R T H E R D A T A ON T H E O X I D A T I O N OF A U T O M O B I L E C Y L I N D E R OILS.* By C. E. Waters.
IN continuation of work already published by the Bureau of Standards, as well as in the Journal of I~l~strial and Engineering Chemistry, a study was made of the rate of oxidation of three automobile cylinder oils when exposed to sunlight and air. This was done by determining the increase in weight and in acidity at intervals during a period of 438 hours' exposure. The accompanying changes in the carbonization values were also determined. The general result was that there is a gradual lessening of the rate at which the weight increases, and at the same time the formation of acid and the carbonization value increase more and more rapidly. The Maumene numbers of the oils increased greatly as a result of oxidation, while there was a marked drop in the iodine numbers. After oxidation the oils showed a much greater tendency than before to emulsify when agitated with water. Filtration through animal charcoal removed, to a certain extent, the substances that caused this tendency, and that raised the carbonization values. When the three oils used in the work above, and eight others, were heated to 25 °o C. for periods ranging from one to seven hours, the formation of carbonized matter proceeded at a rapidly increasing rate. The same was true of the eleven oils when heated for three hours at various temperatures from 23 °0 to 280 ° C. It was found that in both cases the greater the carbonization value at first, the more rapidly did it increase as the tempera* Technologic Paper No. 73.