114 The Philippine Journal of Science i9n 



retort. But this method gave neither the close temperature 

 control nor other results desired. Also the cylinder oils sub- 

 mitted for the bath gave unsatisfactory results under high tem- 

 peratures; consequently the method was abandoned. 



In June, 1916, an improved experimental plant was set up 

 and operated. The plant consisted of a cylindrical iron retort 

 mounted at a suitable height and heated electrically in such a 

 manner that the inside temperature could be closely controlled 

 over a range in temperature of 500° C. The capacity of the 

 retort was from 10 to 15 kilograms, varying with the specific 

 gravity of the wood. The four heating coils were made of 

 No. 18 "ni-chrome" wire arranged to give an approximate 

 reading of 10 amperes for each coil. The wires were wound 

 about the retort connected in parallels, insulated from the sides 

 of the retort by a layer of asbestos board, and covered on the 

 outside by a shell filled with a layer of asbestos powder 6 centi- 

 meters thick. This outer layer left slight chance for loss of heat. 



The control of the temperature was effected by inserting re- 

 sistance and by breaking the main circuit. Each coil in the 

 resistance cut from the circuit gave a rise of 2 amperes current. 

 This arrangement gave a very satisfactory temperature control. 



The condensation of the distillates and the scrubbing of the 

 noncondensible gases occurred in a coil made of lead pipe 

 2.5 centimeters (1 inch) in diameter fitted inside an ordinary 

 barrel of strong material and connected on the outside to a 

 small tower from which extended pieces of glass tubing 400 

 centimeters long and of diminishing diameter. This tubing 

 aided in condensing the lighter product and carried off the 

 noncondensible gases. The tar trap for catching the heavy 

 distillates was placed between the retort and the condenser. 

 It consisted of a piece of iron pipe 10 centimeters (4 inches) 

 in diameter, capped at both ends and fitted with a pet-cock at 

 the bottom. Standardized thermometers were used in noting 

 the temperature changes, which were taken at the center of 

 the charge. Corrections for the emergent stem of the ther- 

 mometer were made in accordance with the common formula 

 0.00016 (T-t) N. 



In order to get comparative data, both fast and slow runs 

 were made on the lots of woods. In operating the still, the 

 weighed charge was placed into the retort and the current was 

 applied. The fast or uncontrolled runs were made with 35 to 40 

 amperes of a 110 volt direct current and occupied about nine 

 hours before practical completion. No effort was made to 

 control the heat except at the beginning of the exothermal reac- 



