July 21, 1922] 



SCIENCE 



83 



changes of atmospheric temperature conditions 

 when the oil is in tank cars. A set of expansion 

 coefficients that fit the observed phenomena will 

 be included. 



The surface tension of petroleum: C. K. Fran- 

 cis and H. T. Bennett. The surface tension of 

 petroleum from different sections of the United 

 States and of the products derived from the vari- 

 ous crudes was determined in order to ascertain 

 whether a relation existed between the surface 

 tension and any other physical properties of the 

 oils. The surface tension of petroleum varies 

 almost directly with the specific gravity, but is 

 influenced by the asphaltic content. The presence 

 of high boiling fractions and high viscosity 

 products tends to raise the surface tension of the 

 lighter petroleum products, such as gasoline and 

 naphtha. The small quantity of sulfur com- 

 pounds, amorphous and crystalline wax, fatty 

 acids and related substances commonly found in 

 petroleum products do not appear to appreciably 

 influence the surface tension. The surface ten- 

 sion at 85° F. of the substances examined varies 

 as follows: 



Crude 28.8 31.2 



Gasoline : 24.4 2o.S 



Naphtha 26.3 29.2 



Kerosene 30.7 31.2 



Gas oil 33.1 



Lubricating oil 36.0 37. .5 



Wax distillate 33.6 36.2 



The change in viscosity of oils with the temper- 

 ature: WiNSLOW H. Herschel. It is often neces- 

 sary to estimate the viscosity of an oil at one 

 temperature from an observation made at an- 

 other. While it is not convenient to do this by 

 equations, because no two petroleum oils are 

 alike, and the relation between viscosity and tem- 

 perature is complex, a graphical method has been 

 developed which it is believed is accurate enough 

 for commercial purposes. The method depends 

 upon the observed fact that the graphs of a log- 

 arithmic viscosity-temperature diagram will, 

 under certain conditions, meet at a point. 



Some notes on the determination of the absolute 

 viscosity of petroleum oils: W. H. Fulweiler and 

 0. W. .Jordan. In connection with the determina- 

 tion of absolute viscosity, of certain samples of 

 petroleum products, it was noted that the viscosi- 

 ties decreased when the sample had been left in 

 the viscosimeter for 24 hours. In other samples, 

 the viscosity increased on standing. Some data is 

 given showing the effect on viscosity of various 

 samples of petroleum, vegetable and animal oils. 

 Some suggestions are made as to the cause of this 

 phenomenon. 



Detonation characteristics of blends of aro- 

 matic and paraffin hydrocarbons: Thomas 

 MiDGLET, Jr., and T. A. Boyd. The compres- 

 sions to which aromatic hydrocarbons can be 

 subjected in internal-combustion engines without 

 detonation are very high as compared to the 

 initial compressions that can be employed when 

 paraffin hydrocarbons are used as fuel. Accurate 

 measurements have been made through a wide 

 range of relative composition of the tendency of 

 blends of these hydrocarbons to detonate in en- 

 gines. Values are given for the limiting com- 

 pression ratio at which the various blends will give 

 combustion that is free from detonation. The 

 new instrumentation used for the accurate meas- 

 urement of the degree of detonation occurring 

 during the combustion of the fuel mixture in the 

 engine is described. 



Tlie catalytic oxidation of insulating oils: C. J. 

 EoDMAN. Many oils used in electrical apparatus 

 for insulating purposes tend to slowly form ' ' de- 

 l^osits ' ' known to the trade as oil sludge. Ex- 

 periments have been carried out in both open and 

 closed systems to substantiate the view that 

 numerous substances may act continuously in 

 small quantities to materially assist in the forma- 

 tion of the undesirable sludge. Such substances 

 found somewhere in the transformer or circuit 

 breaker construction are: copper, brass, lead, 

 iron, tin, organic resins, oxidized asphaltic "var- 

 nishes ' ' and some loading materials such as mag- 

 nesia, calcia and a small proportion of certain 

 driers found in the protective paints. Properly 

 protected materials of electrical apparatus con- 

 struction are discussed as well as the desirability 

 of protecting the oil from oxygen contact. 



Corrosion of petroleum refining equipment: 

 E. E. Matthews and P. A. Crosby. The authors 

 have shown in earlier papers that in refining Mid- 

 Continent petroleum in a so-called pipe still 

 hydrochloric acid was formed, due to hydrolysis 

 of tlie magnesium chloride in the brine associated 

 with the petroleum. Ammonia has been used in 

 the fractionating system to reduce the corrosion 

 caused by the acid. The cost has beeen smaU and 

 results gratifying. This paper shows that 

 hydrochloric acid is also produced when Mid- 

 Continent crude is refined in shall stills ar- 

 ranged in series for continuous operation. The 

 action was especially noted in stills where the oil 

 temperatures were 175° C. to 250° C, and where 

 bottom steam was used. The acid corrosion was 

 also noted in a heat exchanger where the outgoing 

 crude oil was not over 110° C. Evidently the acid 

 formation was small there, however, as the ex- 



