ANALYSIS, REFINING, AND COMPOSITION. 

 DESCRIPTION OF APPARATUS. 



29 



The refining still was of the continuous type with two phases, 

 giving two distilled products and one undistilled residue. It was 

 designed by the makers especially for this work, since stills of this 

 type for the refining of turpentine had not previously been used or 

 manufactured in this country. 



IK >I LING-CAP SECTIONS. 



The boiling-cap section, shown diagrammatically in figure 15, is 

 the typical and important division of the column, the other kinds of 

 sections being modifications of this typical section. Each section 



FIG. 16. Pressure regulator. 



is 14 by 12 inches inside diameter, and is supplied with eight boiling 

 caps and two return pipes. The liquid level on each section is kept 

 even with the top of the return pipes, and the vapors from the sec- 

 tion below are made to pass through this liquid by means of the 

 boiling caps ; the rim of each cap is slotted so that the vapor passes 

 through the liquid in small bubbles, and good contact between the 

 ascending vapor and the descending liquid is thus obtained. 



