208 LEGUMINOS^. 



a few years of rest be occasionally allowed. Clay or earth is sometimes 

 smeared over the bare wood. 



The trees sometimes exude spontaneously a greenish gum-resin of 

 slightly bitter taste, but totally devoid of balsamic odour. It has been 

 anal3^zed by Attfield (see opposite page). 



Secretion of the Balsam— No observations have yet been made 

 as to the secretion of the balsam in the wood, or the part that is played 

 by the operation of scorching the bark. Neither the unscorched bark 

 nor the wood, as we have received them, possess any aromatic odour. 



The old accounts speak of a very fragrant resin, far more valuable 

 than the ordinary balsam, obtained by incisions. We have made manj^ 

 inquiries for it, but without the least success. Such a resin is easily 

 obtainable from the trunk of M. Toluifera. 



Description — Balsam of Peru is a liquid having the appearance of 

 molasses, but rather less viscid. In bulk it appears black, but when 

 examined in a thin layer, it is seen to be of a deep orange brown and 

 perfectly transparent. It has a balsamic, rather smoky odour, which is 

 fragrant and agreeable when the liquid is smeared on paper and warmed. 

 It does not much affect the palate, but leaves a disagreeable burning 

 sensation in the fauces. 



The balsam has a sp. gr. of I'lo to 1"16. It may be exposed to the 

 air for years without undergoing alteration or depositing crystals. It is 

 not soluble in water, but yields to it a little cinnamic and traces of 

 benzoic acid ; from 6 to 8 parts of crystallized carbonate of sodium are 

 required to neutralize 100 parts of the balsam. It is but partially 

 and to a small extent dissolved by dilute alcohol, benzol, ether or 

 essential or fatty oils, not at all by petroleum-ether. The balsam 

 mixes readily with glacial acetic acid, anhydrous acetone, absolute 

 alcohol or chloroform. Its rotatory power is very insignificant. 



Chemical Composition — The peculiar process by which balsam of 

 Peru is obtained, causes it to contain a variety of substances not found 

 in the more natural resin of Myroxylon Toluifera ; hence the two drugs, 

 though derived from plants most closely allied, possess very different 

 properties. 



Three parts of the balsam mix readily with one part of bisulphide of 

 carbon, yet a further addition of the latter will cause the separation of a 

 brown flocculent resin. If the balsam be mixed with thrice its weight 

 of bisulphide, a coherent mass of dark resin, sometimes amounting to 

 about 38 per cent, of the balsam, is precipitated. The bisulphide of 

 carbon forms then a perfectly transparent brown liquid. If this solution 

 is shaken with water, the latter removes Cinnamic and Benzoic acids. To 

 separate them, ammonia is cautiously added, yet not in excess.^ The 

 solution of cinnamate and benzoate thus obtained and duly concentrated, 

 yields both these acids in white crystals on addition of acetic or hydro- 

 chloric acid. 



The resin separated by means of bisulphide of carbon as above stated, 

 is a black brittle amorphous mass, having no longer the specific odour of 

 the balsam. It is soluble in caustic alkalis, also in alcohol ; the solution 



^ By saturating the acid aqueous liquid forms the whole mixture into an emulsion, 

 with ammonia, it assumes a transient bright from which the cinnamem again separates 

 yellow hue ; an excess of ammonia trans- but imperfectly. 



