322 JOURNAL OF FORESTRY 



Xotc on the Preparation of J^iirpcutinc, Rosin, and Gum from Bos- 

 zi'cUia scrrata (Ro.vb.) Gnm-olco-rcsin. By R. S. Pearson, Forest 

 Economist, and Puran Singh, Chemical Adviser of the Forest Research 

 Institute, Dehra Dmi. The Indian Forest Record, Vol. VI, Pt. VI, pp. 

 303-345, 1918. Superintendent, Government Printing, Calcutta, India. 

 Price, IS. 2d. 



This paper contains the results of field and laboratory investigations 

 for the purpose of determining the best method of obtaining the crude 

 gum-oleo-resin of the Indian tree Boswellia serrata, and also of sepa- 

 rating and determining the commercial uses and value of its chief com- 

 ponents — gum, rosin, and turpentine. Plans of a plant are added for 

 obtaining these products on a commercial scale. The study also in- 

 cludes a determination of the number of trees available in Indian Gov- 

 ernment forests for exploitation. The experiments extended over a 

 period of 5 years (1908- 191 2). 



Boswellia serrata is one of some 18 species now known belonging to- 

 the family Burseracea, a group of plants which is in no way related to 

 the conifers yielding the world's supply of naval-stores products. Most 

 of the species of Boswellia occur in tropical Africa and India. Bursera 

 simaruba, a south Florida tree of the same family, is the only member" 

 of this family represented in the United States. Unlike the pine trees, 

 which yield oleo-resin only from the living wood, Boswellia and its 

 family relatives yield gum-oleo-resin only from the living bark. ]\f ore- 

 over, the exuding gum-oleo-resin of Boswellia quickly congeals when 

 exposed to the air, while the oleo-resin of pines flows continuously for 

 several months, only at the end of the turpentine season becoming 

 solidified on the scarified "faces" of the trees. The crude gum-oleo- 

 resin of Boswellia has long been known and locally used in India as a 

 frankincense and for medicinal purposes. It is now said to be equal in 

 quality as a substitute for the Arabian and African frankincense. 



Boswellia serrata is a medium to large sized deciduous tree, with 

 thin scaly bark, common on the driest and most exposed slopes of hills 

 throughout India, often forming pure, open forests of considerable ex- 

 tent. The 24 different government forest divisions contain 42,694,oi6' 

 trees suitable for tapping, or an average of 1,777,917 trees to each for- 

 est division. In terms of the American turpentine "crops" of turpen- 

 tine timber (8,000 to 10,000 trees), this number would amount to from 

 4,269 to 5,336 "crops." 



The method of "tapping" finally recommended for Boswellia serrata 

 consists in blazing or shaving ofif a 6-inch-wide girdle of living bark to- 



