Table 3-1. Physical properties of cargo oil sample from No. 4 port tank and 

 "thick" slick sample taken on December 19 (J. H. Milgram, MIT). 



Property 



Cargo sample 



Slick sample 



Specific gravity 

 Surface tension 

 Viscosity, @ 10°C 

 Pour point, ASTM D97-66 



0.96 

 35 dynes /cm 

 33,298 cp 



2°C 



0.96 

 35.5 cynes/cm 

 71,977 cp* 



2°C 



* The slick sample contained about 4% water, affecting the viscosity measure- 

 ment. 



that is normally added to straight-run No. 6 fuel oil to improve handling 

 characteristics. The 2°C pour point is another indication of the substantial 

 fraction of cutter stock present in the cargo oil. An important observation, 

 made by Milgram early in the spill, was that the specific gravity of the 

 residue remaining after distillation to 210°C also exhibited a spevific 

 gravity of 0.96. This was an early indication that the oil was not going to 

 sink of its own accord, even after prolonged weathering. 



Milgram also measured the surface tension of water pipetted from beneath 

 a thin film of oil, obtaining a value of 79 dynes/cm, as well as the surface 

 tension of water with a thin oil film on top, at 59 dynes/cm. The pour point 

 reported above is the "upper pour point" as defined by ASTM D97-66, and is 

 measured by (a) placing oil in a 1-inch diameter tube, (b) warming it up to 

 dissolve waxy components, and (c) then cooling it and measuring the tem- 

 peratures at which the oil does not move for 5 seconds, with the tube held 

 horizontally. Adding 3°C to the final temperature gives the "upper pour 

 point." Milgram notes that although the oil did not move for the required 5 

 seconds, it would begin to flow before 10 seconds had elapsed. 



On December 22, Milgram gave aliquots of his December 19 samples to R. 

 Sexton of the University of Rhode Island. On December 23, these samples were 

 analyzed by gas chromatography by J. Quinn, URI, according to the following 

 procedure. 



Chemical analysis by gas chromatography 



Two drops of each sample was transferred to 10-milliliter pear-shaped 

 flasks using Pasteur pipettes, and two drops of CS2 were added to dissolve 

 the oil. Each sample was injected into a 5711 gas chromatograph under the 

 conditions listed in Table 3-2. A standard hydrocarbon mixture was injected 

 for identification of the peaks in the chromatograms, which are shown in 



71 



