18 BULLETIN 1036, U. S. DEPARTMENT OF AGRICULTURE. 
Table 4. — Comparative yield of 'water -gas tar from different oils. 
Mixture contains- 
Volume 
Class of oil. 
Base. 
produced. 
Paraffin 
do 
Per cent. 
2 to 4 
Gas oils 
6 to 10 
do 
8 to 12 
Asphaltic 
10 to 15 
Crude oils 
do 
12 to 18 
PRODUCTION OF TAR IN THE UNITED STATES. 
The figures given in Table 5 show the number of gallons of coal tar 
produced in the United States since 1904: 
Table 5. — Production of coal tar in the United States. 
Year. 
Retort tar. 
By-product tar. 
1904 
1908 
1912 
1915 
1917 
41,726.970(5) 
58.541.220(5) 
40,489,855(5) 
47,863,192(7) 
53,318,413(7) 
27,771,115(5) 
42,720,009(5) 
94,306,583(6) 
138,414,601(7) 
221,999,264(7) 
No direct figures are available on the amount of tar produced by 
each type of retort or coke oven throughout this period. Some 
general idea may, however, be obtained from the following list of 
coke ovens in existence at the end of 1917: (8.) 
Rothberg 281 
Roberts 36 
Didier 150 
Total. 
Koppers 3, 374 
Semet-Solvay 1, 831 
United Otto 2, 032 
TVilputte 78 
Gas machinery 60 
Klonne 27 
The amount of water-gas tar produced and sold in this country as 
given by the United States Geological Survey is shown in Table 6 : 
Table 6. — Production of water-gas tar in the United States. 1 
Idle. 
869 
571 
Year. 
Produced and 
sold. 
1905 
1908 
1912 
1915 
1917 
Gallons. 
9,230,411(9) 
9,168,834(5) 
34,000,000(6) 
51,381.911(7) 
59,533,208(7) 
1 Fulweiler (56) gives the production of water-gas tar in 1918 as approximately 70,000,000 gallons; in 1919, 
75,000,000 gallons; and in 1920, 80,000,000 gallons. 
