3. Balsam of Tolu.—This substance is obtained from the Toluifera balsamum, a tree which grows in South America. The balsam flows from incisions made in the bark. It comes to Europe in small gourd shells. It is of a reddish brown colour and considerable consistence, and when exposed to the air it becomes solid and brittle. Its smell is fragrant, and con tinues so even after the balsam has be come thick by age. When distilled with water, it yields very little volatile oil. but impregnates the water strongly with its taste and smell. A quantity of ben zoic acid sublimes, if the distillation be continued. Mr. Hatchett found it solu ble in the alkalies, like the rest of the balsams. When he dissolved it in the smallest possible quantity of lixivium of potash, it completely loses its own odour and assumes a most fragrant smell, some what resembling that of the clove (pink. This smell," Mr. Hatchett observes, " is not fugitive, for it is still retained by a solution which was prepared in June, and has remained in an open glass during four months." When digested in sul phuric acid, a considerable quantity of pure benzoic acid sublimes. When the solution of it in this acid is evaporated to dryness, and the residuum treated with alcohol, a portion of artificial tannin is ob tained ; the residual charcoal amounts to 0.54 of the original balsam.
4. Balsam of Peru is obtained from the Myroxylon Peruiferum. The tree is full of resin, and the balsam is obtained by boiling the twigs in water. It has the consistency of honey, a brown colour, an agreeable smell, and a hot acrid taste. When boiled with water for some time, the liquid separated by thevfilter reddens vegetable blues, and deposits crystals of benzoic acid on cooling. The water con tains no other substance. When distilled with water, it yields a very small quantity of reddish limpid oil. A saturated solu tion of carbonate of soda forms with this balsam a thick mass. When diluted with water, and heated, a portion is dissolved. The solution, when saturated with sul phuric acid, deposits crystals of benzoic acid. One part of the balsam, treated with one part of potash dissolved in four parts of water, formed an opaque solu tion, which gradually separated into two portions : the uppermost, a clear oil, with sonic grey flakes at its lower surface ; the undermost, a dark brownish red opaque solution. This last solution, when saturated with sulphuric acid, let fall a resinous-like substance, dissolved by boil ing, while benzoic acid crystallized. Ni tric acid acts upon the balsam with ener gy, and gives it an orange yellow colour, when assisted by heat. When distilled with a sufficient quantity of this acid di luted, the liquid in the receiver smells of bitter almonds. When this balsam is treated with sulphuric acid, artificial tan nin is also'formed, and the residual char coal amounts to no less than 0.64 of the original weight of the balsam.
5. Styrax.—This is a semifluid juice, said to be obtained from the Styrace offi cinale, a tree which grows in Virginia, Mexico, and some other parts of America. It is prepared in the island Cobrass, in the Red Sea, from the bark of a tree call ed rosy mallos by the natives, and consi elered by botanists as the same with the American species. The bark of this tree is boiled in salt water to the consistence of bird-lime, and then put into casks. Bouillon Is Grange has published an ac count of its properties. Its colour is greenish, its taste aromatic, and its smell agreeable. It is easily volatilized by heat. When treated with water, benzoic acid is dissolved. It is totally soluble in alco hol, except the impurities.. When ex posed to the air, it becomes harder, and absorbs oxygen. When distilled, it yields an acidulous water, having the odour of benzoic acid, a limpid colourless hot oil, a solid coloured oil, benzoic acid, and a Mixture of carbonic acid and carburetted hydrogen. The charcoal is light, and con
tains some oil.
Solid balsams. The solid balsams at present known are only three in number; namely, 1. Benzoin. 3. Dragon's blood.
2. Storax.
1. Benzoin.—This substance is the pro duce of the styrax benzoe, a tree which grows in Sumatra, &c. and which has been described by Dr. Dryander. Benzoin is obtained from this tree by incision ; a tree yielding three or four pounds. It is a solid, brittle substance, sometimes in the form of yellowish white tears, joined to gether by a brown substance, and some times in the form of a brown substance, not unlike common rosin. It has a very agreeable smell, which is increased by heating the benzoin. It has little taste. Its specific gravity is 1.092. Alcohol dis solves it when assisted by a gentle heat, and forms a deep yellow solution, inclin ing to reddish brown. When this solu tion is diluted with water, the benzoin precipitates in the form of a white pow der. It is precipitated also by muriatic and acetic acids, but not by the alkalies. A few drops of sulphuric acid likewise precipitate the benzoin ; but an additional quantity re-dissolves it, and forms a li quid, of the colour of port wine. Nitric acid acts with violence on benzoin, and converts it into an orange-coloured mass. When assisted by heat, the acid dissolves the benzoin ; and as the solution cools,. crystals of benzoic acid gradually sepa rate. Mr. Hatchett ascertained, that by this process a quantity of artificial tannin is formed. Sulphuric acid dissolves ben zoin, while benzoic acid sublimes ; the solution is at first a deep red. By conti nuing the digestion, a portion of artificial tannin is formed, and the charcoal evolv ed amounts to 0.48 of the benzoin dis solved. Acetic acid dissolves benzoin without the assistance of heat. When heat is applied, the solution, as it cools, becomes turbid ; owing to the separation of benzoic acid. Benzoin is dissolved by a boiling lixivium of the fixed alkalies,; a dark brown solution is formed, which becomes turbid after some days exposure to the air. Ammonia likewise dissolves benzoin sparingly.
2. Storax.—This is the most fragant of all the balsams, and is obtained from the styrax officinalis, a tree which grows in the Levant, and it is said also in Italy. Sometimes it is in the state of red tears : and this is said to he the state in which it is obtained from the tree. But common storax is in large cakes, brittle, but soft to the touch, and of a reddish brown co lour. It dissolvesi n alcohol.
3. Dragon's blood.—This is a brittle substance, of a dark red colour, which comes from the East Indies. There are two sorts of it ; one in small oval drops, or tears, of a fine deep red, which be comes crimson when the tears are reduc ed to powder ; the other is in larger masses, some of which are pale red, and others dark. It is probably obtained from different kinds of trees; the calamus draco is said to furnish most of what comes from India. The dracxna draco and the pterocarpus draco are also said to furnish it. Dragon's blood is brittle and taste less, and has no sensible smell. Water does not act upon it, but alcohol dissolves the greatest part, leaving a whitish red substance, partially acted upon by water. The solution has a fine deep red colour, which stains marble, and the stain pene trates the deeper the hotter the marble is. It dissolves also in oils, and gives them a deep red colour also. When heated, it melts, catches flame, and emits an acid fume similar to that of benzoic acid. When digested with lime, a portion of it be comes soluble in water, and it acquires a balsamic odour.