37 



ANALYTICAL WORK. 



As both the rosin and the volatile oil are easily soluble in chloroform, ether, carbon disnlphide, 

 etc., their separation from wood by any of the above solvents woidd appear to be an easy matter. 

 But an exact quaiititative determinaticm of the volatile oil i)resents considerable ditficnlties, and 

 for these reasons: (1) Wood cau not be dried free from moisture without driving off some of tbe 

 volatile hydrocarbons; (:i) the ether extract cau not \h' freed eutu-ely from ether without some 

 loss of the volatile oil. 



If a weighed (juantity of wood shavings is exhausted with ether, the residue dried at 100° C. 

 and weighed, the total loss thus found will represent: 



The moisture == H. 

 The rosin = h'. 

 The vohitile hydrocarbons = 7'. 



It is suflicieut to determine two of these factors; tiie third could then be determined by differ- 

 ence. But as has been mentioned before, the ether extract can not be obtained in any degree of 

 purity without loss of turpentine. The evaporation of ether iu a stream of dry air, as proposed by 

 Dragendorf, for the estimation of essential oils iu general, docs not give satisfactory results with 

 turpentine oil, as Dragendorf himself observed. 



A weighed quantity of a mixture of rosin and oil, made up in about the same proportion as 

 they exist in crude turpentine, was dissolved in a suitable amount of ether. The latter was then 

 evaporated in a current} of dry air till the odor of ether was hardly noticeable. The mixture was 

 found to have gained considerably in weight by retaining ether in the thick sirupy oleorosin. It 

 was only by heating at 100^ C. fm- some time tiiat all of the solvent could be driven off, and then 

 the mixture was found to have lost in weight. Repeated trials proved that this method could not 

 be used safely. 



r^7 



Fig. 17. — Mctlioil ol' chemical aualysis of tmiicntine. 



An attempt w:is then made to determine the ([uantities B and E, and tlius lind T by dif 

 ference. A weighed quantity of wood shavings was placed in a small flask, a. The latter was 

 connected on (me side with a tray of drying bottles, on the other with two CaCl_. tubes, I> and c, 

 sinnlar in size and form. Tlie tlask is immersed in boiling wati'r and a current of dry air is ])asscd 

 through the whole apparatus for one ami oue-half hours. The Mask is then cooled and air is 

 passed for one and one half hours longer. (Fig. 17.) 



It was thought that while l> would retain all the moisture and a port ion of the volatile com- 

 pounds, c would retain about the same amount of the v<datile ])roducts only, (lain in weight of c 

 subtracted fnnn that of h would then give the moisture H. The sample of wood shavings is then 

 exhausted with ether, the latter evaporated, and the residue heated at about 140° to 1,50'^ to con- 

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



But it was soon found by experiments upon i>ure turpentine oil that the two ('aCUj tubes did 

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

 stances, the chief one being the amount of moisture alread.v j)resent iu the CaCl.. tubes. 



