210 



BROOKS. 



addition to the crystalline substance, when the cold aqueous solution is treated 

 with phenylhydrazine. The irritating odor of the original distillate is very sug- 

 gestive of acrolein, but its presence was not proved. 



The presence of a very small amount of methyl alcohol was shown by neutraliz- 

 ing the aqueous, acid solution with caustic soda and distilling over about one- 

 third of the solution. The distillate was saturated with potassium carbonate and 

 redistilled. The first small fractions were then tested for methyl alcohol by 

 oxidizing to formaldehyde with hot copper oxide and then testing for the aldehyde. 



The presence of acetone among the distillation products was shown in another 

 experiment in which the distillation products were treated with an excess of 

 dilute caustic-soda solution and distilled. The first few cubic centimeters were 

 tested for acetone by the method of Gunning 2T in which test iodoform is formed 

 on the addition of a solution of iodine in ammonium iodide and a few drops of 

 dilute ammonium hydroxide. This was confirmed by the test depending upon the 

 ability of acetone to dissolve mercuric oxide in an alkaline solution. 2S 



The products given off by Manila copal up to the point at which the 

 melt has a temperature of about 330° may thus be summarized. 



Table II. — Substances given off by Manila copal during the first stage of the 



decomposition, up to 330°. 



Substance. 



Per cent. 



Carbon dioxide __ 



3.2 

 2.4 



0.5 



0.2 



0.2 

 1.5-11.2 



3. 0-6. 



Water . 



Formic acidl 



Acetic acid) 



Formaldehyde, acetyl formaldehyde, furfuraldehyde, 



methyl alcohol, and acetone, approximately. 

 Gaseous hydrocarbons _- 



Pinene, limonene, dipentene, £jpinene,and camphene, 



variable. 

 Resin oil, variable, usually from _ _ 





DISCUSSION OF RESULTS. 



The quantitative results recorded in this portion of the paper should 

 be considered as those obtained from commercial Manila copal of average 

 age and of the first and second grades. Any discussion of the properties 

 of copals would have to take into account the wide differences in the age 

 of the specimens examined and the consequent variations resulting there- 

 from. The differences in the yields of terpenes obtained have already 

 been pointed out. Since the resin absorbs oxygen quite rapidly and 

 increases in acid value it is to be expected that the amounts of carbon 

 dioxide, water, and other substances will vary according to the age of the 

 resin which is distilled. 



27 Ztschr. f. anal. Chem. (1885), 24, 147. 



28 Gunning and Reynolds. Ztschr. f. anal. Chen:. 



1885), 24, 148. 



