COAL-TAR AND WATER-GAS TAR CREOSOTES. 
27 
full charge was admitted along with air in a slow stream through 
the separatory funnel F. In this way only very small quantities of 
water were present at one time in the still, and the slow drying that 
would otherwise be necessary was avoided and at the same time the 
danger from frothing was eliminated. Air-cooled glass condensers D 
were used throughout the work, but they were supplemented by a 
water-cooled reflux condenser R at the receiver during the early 
stages of the distillation. The apparatus could be used for distilla- 
tion in a stream of air, or without air, or with steam, as the case 
might require, and could be changed from one system to another 
during the distillation. 
APPARATUS AND METHOD USED IN TESTING THE CREOSOTES. 
APPARATUS FOR DISTILLING TARS. 
Fig. 11.— Apparatus used for distilling tars. 
For the reader's convenience, a complete description of the appa- 
ratus and methods used in the testing of the creosotes is given in 
detail, although part of it has been published before. (12) 
Distillation test. — In all distillations a Hempel flask was employed. 
Hempel flasks are usually made from Jena glass or its equivalent. 
The bulb is of such a capacity that, when it is filled to the bottom of 
the neck, it holds 500 cubic centimeters, a variation of 25 cubic centi- 
meters being allowed. The neck of the flask is 1 inch in diameter 
and 7 J inches long from the top of the bulb to the delivery tube and 
extends 3 inches above the delivery tube. The delivery tube makes 
