296 PROCEEDINGS OP THE AMERICAN ACADEMY. 



encloses a section of country 140 miles long by 150 miles broad, rising 

 gradually from the sea to the mountains with a varying altitude from 

 150 feet to 500 feet. Oil is found chiefly in the Upper Eocene of the 

 Tertiary formation, where it is held under pressure between impervious 

 layers of slate and sandstone. 



Nodules of calcite are frequently found embedded in the sandstone, 

 and crystals of calcite twinned, resembling those found in the Ohio Tren- 

 ton-limestone, oil-bearing rock. The oil strata are full of sea-shells, a 

 good indication as to the origin of the oil formations. There are great 

 variations in the depths of the wells. For example, the wells of the 

 Amaze field are approximately 2000 feet in depth, while those of the 

 Miyagawa field, only six miles distant, are 700 feet deep; the wells of 

 the Niitsu field are still shallower, 600 feet. The Nagaoka wells are 

 800 feet in depth. Nevertheless the oil strata at the different depths 

 are essentially of the same formation. The sandstone in wiiich the 

 Nagaoka oil is found is coarser than that of the other fields. On the 

 surface of the Niitsu oil territory are immense beds of peat which are 

 used f^or fuel. 



Although the oil fields of Japan are situated in close proximity, speci- 

 mens of oil from the different fields differ as essentially in composition 

 as the variations in specific gravity indicate. As will appear later, 

 the Amaze, Miyagawa, and Hirei fields yield parafRne in considerable 

 quantities. While the hydrocarbons above C7H14 do not include mem- 

 bers of the series C„H2,j+2) ^t least so far as it appears from analysis of 

 distillates prepared on a laboratory scale, the lower distillates do con- 

 tain members of the paraffine series. 



The paraffine hydrocarbons with low boiling points, such as the 

 butanes, pentanes, and hexanes, have an agreeable sweetish odor that is 

 easily recognizable, and quite different from the pungent harsh odor of 

 the methylenes. The odor of the paraffines is more apparent in the 

 Miyagawa oil than in any other of the Japanese oils we have seen, and 

 somewhat less in the Amaze oil. When these hydrocarbons with low 

 boiling points are present, the crystalline paraffine hydrocarbons C„H2„+2 

 are usually to be found. 



Considerable quantities of gas were formerly obtained from the Amaze 

 oil territory, but the supply now seems to be exhausted, at least so far as 

 wells have been bored; some gas escapes from the shallow Miyagawa 

 wells, more from the shallow wells of the Niitsu territory. As wells are 

 sunk deeper in this territory it is probable that lighter oils will be found. 

 On account of the friable condition of the oil rock and the danger of 



