abstracts: technology 507 



TECHNOLOGY. — Further data on the oxidation of automobile cylinder 

 oils. C. E. Waters. Bureau of Standards Technologic Paper 

 No. 73. Pp. 20. 1916. 



In continuation of work already published by the Bureau of Stand- 

 ards, as well as in the Journal of Industrial 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 carboniza- 

 tion 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 250°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 230° 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 temperature was raised or the time of heating ex- 

 tended. In other words, an oil which had a low carbonization value 

 if heated to 250° for two or three hours, and an oil showing a some- 

 what higher value under the same conditions, will be farther and farther 

 apart as the conditions become more strenuous. This being so, it is 

 unnecessary to prolong greatly the time of heating in routine testing. 



The need of extreme care in taking and preserving samples, as well 

 as in testing them, was emphasized, because the presence of rust par- 

 ticles or other extraneous matter increases the amount of carbonization. 



In conclusion it is shown that the carbonization value is independent 

 of the flash and fire points and of the evaporation loss on heating. 



C. E. W. 



