COAL-TAR AND WATER-GAS TAR CREOSOTES. 
43 
next oldest the next greatest residue. Only one by-product tar 
creosote exceeded 2 per cent sulphonation residue in any of its 
fractions. 
WATER-GAS-TAR CREOSOTES. 
The data obtained on the water-gas-tar creosotes examined are 
shown in figure 24. In figure 24c attention is again directed toward 
the fractions from 260° to 300° C, the sulphonation residues being 
greater in general than in any other fractions obtained in distillation. 
This is the same as the indication on coal-tar creosotes. Very few 
data were obtained on the temperatures at which these tars were 
produced. It is, however, to be noted that the oils showing the 
highest indices of refraction, the highest specific gravities, and the 
lowest sulphonation residues were produced at the highest tem- 
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TEMPERATURE °C 
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c 
Fig. 24.— Physical and chemical measurements effractions of all authentic water-gas tar creosote. 
A. Index of refraction values. B. Specific gravity values. C Sulphonation residues. 
peratures, and in one or two instances the temperature is given at 
between 1300° and 1400° F.y equivalent to 700° to 750° C. 
Out of 19 water-gas tars 5, or approximately one-quarter, produced 
creosotes having 2 per cent or less of sulphonation residue. Eight 
produced creosotes having 5 per cent sulphonation residue. All of 
these tars were manufactured in plants that are using temperature 
regulation in the operation. In this age of scientific management a 
closer control of manufacturing operations may reasonably be 
expected, which will result in a probable increase in water-gas tar 
having a low sulphonation residue. 
Statistics on the annual production of water-gas tar are given in 
Table 6. In 1912 the total production was nearly one-half of the 
total production of coal tar. The amount sold, however, was only 
one-quarter of the amount of coal tar sold. 
