94 HENRY G. SMITH. 



Rother 1 considers glycerol " as unsatisfactory as all other 

 agents previously tried. The alleged occasional success 

 with sundry corrigents can only be accounted for by the 

 fact that there are numerous varieties of kino, and that 

 one or more of these may not be susceptible of this change." 

 It is very probable that this is so, and it is remarkable that 

 while some Eucalyptus kinos gelatinize very readily, others 

 do not do so even after the lapse of many years. 



About seven years ago I made tinctures (1 in 10) of half 

 a dozen Eucalyptus kinos, but omitted the glycerol. These 

 were put up in glass stoppered bottles and kept in the dark 

 continuously. The kinos of E. amygdalina, E. macror- 

 rhyncha and E. piperita readily gelatinized and formed a 

 perfect jelly after a comparatively short time. The kino 

 of E. corymbosa has become thick but not even now a jelly, 

 that of E. punctata has slightly thickened, but the kino of 

 E. calophylla has uudergone no alteration after all these 

 years. The evidence thus obtained has been followed up 

 with gratifying results. 



The questions naturally arising are, why this variability 

 in gelatinization when the tinctures are made under iden- 

 tical conditions, and what is the cause of the gelatinization? 

 These will be considered together. It may perhaps be 

 generally accepted that the cause of the gelatinization is 

 the same in those Eucalyptus kinos which gelatinize and 

 in the kino of Pterocavpus marsupium. 



Pereira considered the jelly to consist principally of 

 pectin and tannic acid (page 238) and Dorvault that it was 

 pectic acid, but Mr. Redwood {Joe. cit.) after experiment, 

 arrived at the conclusion that neither pectin nor pectic 

 acid was present in the jelly, but thought that the change 

 was traceable to "ulmic acid " or "humus." 



1 American Journal of Pharmacy, 1886, and Pharm. Journ., July 1886, 

 p. 67. 



