SPECIFIC GRAVITY. 155 



of 88°F„ which the petroleum has when coming out from the well. 

 When this petroleum is stored in the iron tanks, the tropical sun 

 heats it to a temperature of ioo°F. and more. The oil expands, its 

 specific gravity changes, and instead of being 0-8917 it will be 0*8869 

 at the temperature of ioo°F. ; in other words it will be lighter, and 

 when the gauge shows that 16,000 gallons are in a tank, this quantity 

 converted at the specific gravity of 0*8917 would give 89, 170 lbs. 

 while it actually weighs only 88,69olbs., that is to say under the 

 above supposition, there would be a loss of 480IDS. on every 10,000 

 gallons owing to the expansion of oil under the influence of 



heat. 



Owing to the custom above alluded to, the quantity of the pe- 

 troleum produced by the oilfields in Burma is recorded in Burmese 

 viss. At the average temperature of the oil when coming fresh 

 out of the well, and at the specific gravity of 0*8917, one barrel 

 of 42 gallons of crude oil would weigh 374*5lbs, As, however, 

 owing to the high temperature of the oil under the influence of the 

 sun the specific gravity is smaller, say 0*8869, one barrel of crude 

 oil will weigh 372*4lbs. For the purpose of comparison it is therefore 

 quite correct to assume that 100 Burmese viss are 1 barrel of 42 

 gallons ; and to convert Burmese viss into barrels, the last two 

 figures must be struck off when the production is given in viss ; for 

 instance, 100,000 viss = 1,000 barrels, the error being 2 °/ in 

 excess. 



Volatility. — No special observations have been made with 

 regard to the volatility of the Burma petroleum, but experience has 

 proved that under the influence of high temperature, crude pe- 

 troleum rapidly decreases in volume. Tank-flats which received their 

 full load at Yenangyoung, show a considerable loss when arriving at 

 Rangoon. 



When the petroleum is left to itself in the natural springs at 



Minbu, it gradually gets more viscous till it resembles asphalt. 



The high specific gravity of the Minbu petroleum may perhaps be 



accounted for by evaporation of the lighter oils. 



( 201 ) 



