78 



of C. iireiiosa 154. We have not been able to obtain the resin of C. iiitnitropica, 

 but judging from analogy- it may be assumed that this wiU be found to differ liut 

 slightly from the resin of C. arcnosa, because the terpene in the leaf oil of both 

 species is mostly limonene, although the optical rotations are in opposite directions. 

 If this surmise is correct, then Australian sandarac may be supplied of quite 

 equal value with similar material from North Africa. It is probable, too, that 

 C. arenosa has a somewhat extensi\-e range, occurring in many parts of New South 

 Wales and Queensland, as well as on Fraser Island. 



The density of the ordinary samples of CaUitris resins which have been 

 determined, ranged from 1-079 to i-o6g at 16° C. The resin of C. Tasmanica 

 from Rylstone was, however, a freshly e.xuded specimen, and this had a specific 

 gravity as low at 1-058. The density of sandarac thus varies somewhat according 

 to the age of the resin when collected. 



It was thought that perhaps some differences could be detected between 

 the CaUitris resins if their optical rotations were taken, as they were all optically 

 active. Solutions were made with the various resins of the strength of i gram 

 picked resin in 5 c.c. acetone, as that substance appeared to be the best solvent 

 for the purpose. Sandarac is easily and entirely dissolved in acetone, and in most 

 instances the reading in a loo-mm. tube with this solution could be taken directly, 

 but where this was not sufficiently distinct, then by adding an equal A'olume of 

 90 per cent, alcohol, the reading was rendered quite sharp. 



It will be observed that all the samples tested, including those of ordinary 

 sandarac, were de.xtro-rotatory, and that the specimens from C. glauca had 

 generally a higher dextro-rotation than had those from C. calcarata. There is 

 but little difference in the rotations of the resins of C. calcarata and ordinary 

 sandarac, but there appears to be little agreement between the activity of the 

 resins and their solubility in alcohol. It may, therefore, be assumed that the 

 differences in the amount of the various acid resins and neutral bodies in the 

 exudations of the various species, govern, to a great extent, their relative solubility 

 in alcohol. The acid resin, whose potassium salt is insoluble in an excess of alcoholic 

 potash, varies somewhat in amount with the resins of the various species. 



The method adopted in the endeavour to arrive at some conclusion as to 

 the relative solubilities in alcohol of these sandarac resins, was to dissolve 2 grams 

 of the picked resin in 10 c.c. of 90 per cent, alcohol, and then to titrate 5 c.c. of 

 this solution with 75 per cent, alcohol (by weight) with repeated agitation, until 

 a permanent and well defined turbidity was reached. All the determinations 

 were made under identical conditions. This strength of alcohol was found to 

 be more satisfactory for the purpose, than either 70 or 80 per cent, alcohol. It 

 will be noticed that the mean solubility of the three samples of ordinary sandarac, 

 shows that 4-6 c.c. of 75 per cent, alcohol was required to render 5 c.c. of the 



