INVESTIGATIONS INTO RESINS. 



337 



c subtracted from that of b would then give the moisture JZ. The sample of wood shavings is 

 then exhausted with ether, the latter evaporated, and the residue heated at about 140° to 150° to 

 constant weight; this gives the rosin B. If L be the total loss by extraction with ether, we have 



But it was soon found by experiments upon pure turpentine oil that the two CaCl 3 tubes did 

 not retain an equal amount of volatile oil. The quantity retained depended upon many circum- 

 stances, the chief one being the amount of moisture already present in the CaCl 2 tubes. 



Even had the tubes retained quantities of turpentine oil, this method would still have the 

 objection that one of the constituents was to be determined by difference — an objection especially 

 serious when the ingredient to be so determined is small in comparison with the materials to be 

 weighed. 



The writer has therefore attempted to make use of a somewhat different principle. A few 

 trials were sufficient to show that the method promised to give satisfactory results. The basis of 

 the method is the same which served for the production of Eussian turpentine oil on a large scale, 

 namely, the distillation of the volatile products from the wood itself, without previously obtaining 

 the turpentine. But instead of condensing the volatile products, their vapors are passed over 

 heated copper oxide, whereby they are burned to water and carbon dioxide. Many trials were 

 made with this method upon pure materials and on samples of resinous wood. As the results 

 were found to be entirely concordant and satisfactory, the method was adopted, and by it were 

 obtained the results presented in this report. 



DESCRIPTION OF THE METHOD EMPLOYED. 



A weighed amount of wood shavings is placed in a straight CaCl 2 tube a. The tube is con- 

 nected on one side by means of a capillary tube with a drier A, which serves for freeing the air 

 from moisture and CQ 2 . The other end of the tube is connected with an ordinary combustion 



wa <UL. 



Fig. 86.-- Method of distillation vt tuipentme. 



tube b containing granulated Cut). The tube is drawn out at one end as is shown in the figure, 

 and the narrow portion is loosely filled with asbestus wool. The connection is made glass to 

 glass, so that the vapors of distillation do not come in contact with any rubber tubing. The 

 forward end of the combustion tube is connected with a Ca01 2 tube c, one-half of which is filled 

 with granulated CaCl 2 and the second half with P 2 5 . Then follows a potash bulb d provided 

 with two straight tubes, the first one filled with solid KOH, the second with P 2 5 . The last tube 

 is connected with an aspirator. 



All the connections having been made air-tight, the connection between the tube a and the 

 drier A is shut off by means of a clamp and the aspirator turned on. When the combustion tube 

 has been heated to dull redness the burner under the air-bath B is lit and the temperature raised 

 to 110°-120° C. The moisture contained in the tube escapes quite rapidly, carrying with it some 

 turpentine oil. The capillary tube at the other end of A practically checks backward diffusion 

 H. Doc. 181 2 2 



