INDUSTRIAL AXD E N GINEERISG CHEMISTRY
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21 per cent. When corrections are applied to obtain tiue induction periods, the values for sample A are from 340 to 355 minutes, a spread of only 4 per cent, and those of sample C from 215 to 235 minutes, a difference of about 10 per cent. These results indicate that the correction factors formulated are true within thelimits of experimental error. [Flood e t al. ( 3 ) stated in their work that the lag was taken as 15 minutes. As they used room temperature for charging the bomb, thiq would be in good agreement with the present work.]
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As an additional illustration, the data on sample C (Table IV) may be considered. I n the case of the steel bomb heated in an oil bath, an observed induction period of 4 hours and
30 minutes mas obtained. Here little glass-dish gum mould be expected if the determination were made a t the end of 4 hours. However, in the case of Ethyl Gasoline Corporation bomb, which gave an observed induction period of 3 hours
DISCUSSION OF RESULTS I n work which involves the comparison of a number of samples of gasoline in a given bomb, correction factors are not of great importance. In this case only the relative valueare sought. However, if the oxygen-bomb induction period is to be made a quantitative figure, the method must be such t h a t a given gasoline will give the same definite value when tested b y different laboratories. As stated before, this could be done by adopting a standard bomb and a standard procedure. This would inyolve considerable expense and new equipment a t many laboratories. On the other hand, by determining the correction for bomb3 b y m e t h o d s described in this paper, concordant results may be o b t a i n e d on b o m b s of widely different physical characteristics. Such a move on the part of the : testing l a b o r a t o r i e s would iron W a out difficulties and c h a n g e t h e 2 status of the oxygen bomb from a 3 2 qualitative t o a q u a n t i t a t i v e c“ test. It w o u l d p e r m i t e a c h l a b o r a t o r y t o u s e i t s present equipment and formulate its own standard procedure. Although 0 IO 20 3 0 4 0 M in the present tests the bombs MINUTES w e r e f i l l e d a t ice temperature, FIGURE2. HEATING cURVE OF ETHYL GAS0any c o n v e n i e n t constant teniLINE c o R p o R A T I o N perature may be used, provided B o h r B I N B O I L I N G the c o r r e c t i o n s are determined WATER under the same conditions. The f o l l o w i n g results on a sample of aviation gasoline illustrate the value of bomb correction factors. The tests were i u n according to government procedure ( 2 ) . This specifies that the sample (200 ml.) be placed in a bomb and 100 pounds oxygen pressure applied a t room temperature. The bomb is then heated to 98-100” C . for 4 hours. The bomb is cooled and the sample remoTecl foi glass-dish gum determination. LABORATORY
GUM Mg./100 ml.
A B C
D
100 (4 checks) 20 (3 checks) 53 2
These erratic results were undoubtedly caused by differences in the heating lags of the various bombs. It has been shown t h a t during the induction period little gum is formed in the sample under test (1, 3, 4). The data on this particular sample of gasoline indicate that laboratory D used a bomb which did not come t o temperature as rapidly as others and the sample had not reached the end of the induction period. It must not be overlooked that oxidation and gum formation can also take place after the bomb has been removed from the bath. No data are available on the rate a t which the gasoline sample cools under these conditions. For some bombs such as the heavy one proposed by Ward ( 5 ) ,described below, i t must be rather slow.
gao +
/
1
1
‘
I
i ’ I
FIGURE3 . AVERAGEC H A N G E , IVVITH TEMPERATURE, OF EFFECTIVE 0x1D . ~ T I O X PRODUCED BY 10 - hl I N u T E H E A T I Y G P E R I O D A T ANY COZST.4NT TEMPERATURE Ratio, 2.7 times per 10’ C.
and 35 minutes on the same sample, an appreciable amount of gum would be expected a t the end of 4 hours, because the induction period has been exceeded b y 25 minutes. The specification for such a test as the Proposed Federal Specification ( 2 ) should be more rigid in nature. Even the temperature range allowed (98” to 100” C.) can cause an error of 10 to 15 per cent in the induction period, The oxygen bomb proposed b y Ward ( 5 ) is constructed of steel with a wall thickness of l l / l e inches, the total weight of the bomb being 75 pounds. The bomb is permanently installed in a steam-heated water bath. As the entire system, including the bath, must be cool when the bomb is charged, the time required t o raise such a mass of water and metal to 100” C. must be considerable. Ward states that ”the period of oxidation begins when the temperature of the gasoline has reached its maximum, as indicat’ed by the pressure recorded on the gage.” Such a statement is, of course, very much in error as is proved b y the results given in the body of the present report. Oxidation occurs throughout the heating-up and cooling-down periods. The lag correction for such a system might be from 1 t o 2 hours. There seems no need for such a heavy bomb. It is recommended that all bomb results be given in terms of true induction periods. This will necessitate only the determination of the rates of temperature rise of each type of bomb under normal test conditions. It would involve very little work on the part of various laboratories and would put the oxygen bomb test on a quantitative basis.
LITERATURE CITED (1) hldrich, E . IT., and Robie, T i . P.,
S.A . E . Journal, 30, 198 (1932). (2) Bur. Standards, Proposed Revision of Federal Specification 2-d for Gasoline (Aviation, Domestic Grade) (3) Flood, D. T., Hladky, J. IT., and Edgar, Graham, paper presented before Petroleum Division at both Meeting of American Chemical Society, Cincinnati, Ohio, Sept. 8 to 12, 1930. (4)Ramsay, J. W., IND.EKG.CHEII.,24, 539-42 (1932). 1.5) Ward, B. P., Oil Gas J . , 31, KO.12, 16 (1932). RECEIVEDJanuary 28, 1933. University, Ithaca, N. Y.
J. W. Ramsay’s present address is Cornell
The heading for the third column in Table I CORRECTION. appearing on page 623, IXDUSTRIAL AND ENGINEERINQ CHEMISTRY for June, 1933, in the article on “Poisonous Spray Residues on Vegetables,” by W. B. White, should read “Grain/lb.,” and not “Gramllb.” as printed.
