100 



I5AC0X. 



Solutions in these solvents leave a brillant varnish coat uliieh, however, 

 dries quite slowly. The resin dissolves only very slowly in cold kerosene 

 and in chloral hydrate, but quite easily on warming with these solvents. 



The use of eletni residues with turpentine and linseed oil has not given 

 us very satisfactory varnishes, for even with e.xcessive quantities of 

 driers, the varnish coat remains somewhat sticky' for three or four days. 

 This elemi residue, however, mixed with varying proportions of Manila 

 copal, melted with boiled linseed oil; and properly thinned with turpen- 

 tine has given \is most excellent varnishes, which give a hard, brillant, 

 and elastic coating on wood. The u.se of the demi resin residue for 

 varnishes seems not only to give a paler and more brilliant varnish than 

 copal alone, but renders the melting of the copal mucli easier. I believe 

 this elemi resin distillation residue has a future as a varnish gum. This . 

 entire question will be taken up by George F. Richmond, Bureau of 

 Science, who is now studying Manila copals. 



In this connection I desire to note a few further experiments on the 

 distillation of Manila elemi. The resin as it comes into the market is 

 often mixed witli bark, dirt, and other impurities. Before shipment 

 to Europe these impurities are usually picked out by hand as far as 

 possible. Solution of the resin in alcohol, filtering, and distilling off 

 the alcohol even in vacuo, leaves a dark colored resin, which in appearance 

 is not at all like elemi. The best method of purifying elemi resin 

 is by solution in benzol, filtering, and distillation of the Ijenzol, when a 

 white resin of the same leafy appearance as elemi is obtained. 



Six and five-tenths kilos of commercial elemi were distilled in the usual manner 

 in vacuo, and the volatile oil redistilled at ordinary pressure. The following 

 fractions, each of about 135 cubic centimeters, were obtained: 



Boiling point, 

 degrees (760 mm.). 



(1) 168-174 



Rotation in a 10 cm 

 tube (degrees). 



99.1 



(2) 174-177 



95.5 



(3) 177-179 



95.0 



(4) 179-181 



92.0 



(5) 181-183 



90.0 



(6) 183-190 



83.0 



(7) 190-210 



63.0 



These fractions were now washed with dilute alkalies, dried and refractioned 

 with the following results: 



No. 



Quantity. 



Boiling 



point, 



degrees 



(760 mm.). 



,30° 

 ^ D 



10 cm. 

 tube. 



N- 



Specific 

 gravity, 



30° 



4° 



1 



cc. 

 300 



169-170 



118.8 



99.0 



1.4680 



0.8345 



2 



440 



170-173 



113.9 



95.0 



1.4680 



0.8357 



3 



170 



173-175 



103.4 



86.5 



1.4684 



0.8363 



4 



160 



175-180 



88.1 



74.0 



1.4697 



0.8396 



5 



45 



180-190 



76.8 



65.0 



1.4712 



0.8463 



