CHEMISTRY. 



is.-; 



Chemical 



Examina. 



tion of 



Nature. 



down the guaiacum of an ash grey, and sulphuric acid of 

 a pale green colour. Acetic ?cid and the alkalies occa- 

 sion no precipitate. Liquid oxymuriatic acid throws it 

 down of a fitit pale blue, which does not change when 

 dried. Diluted nitnc acid occasions no change at first ; 

 but after some hours the liquid becomes green, then blue, 

 and at last brown, and at that period a brown-coloured 

 precipitate falls down. If water be mixed with the liquid 

 when it has assumed a green or a blur colour, green and 

 blue precipitates may be respectively obtained. 



Su'phuric ether does not act so powerfully on guaia- 

 cum as alcohol. The solution obtained by means of it, 

 exhibits the same properties when treated with re-agents 

 as that in alcohol. 



The alkaline solutions, both pure and in the state of 

 carbonates, dissolve guaiacum with facility. Two ounces 

 of a saturated solution of potash dissolved about 65 

 grains of guaiacum ; the same quantity of ammonia only 

 25 grains; or guaiacum dissolves in about 15 parts of 

 potash, and 35 parts of ammonia. 



Most of the acids act upon guaiacum with consider- 

 able energy. 



Sulphuric acid dissolves it, and forms a deep red liquid, 

 which deposites while fresh a lilac-coloured precipitate 

 when mixed with water. When heat is applied, the 

 guaiacum is charred. 



Nitric acid dissolves guaiacum completely without the 

 assistance of heat, and with a strong effervescence. When 

 the solution is evaporated, it yields a very large quantity 

 of oxalic acid. No artificial tannin appears to be formed, 

 but rather a substance possessing the properties of ex- 

 tractive. Diluted nitric acid converts guaiacum into a 

 brown substance, similar to the precipitate obtained hy 

 nitric acid from the alcoholic solution of guaiacum. This 

 brown matter possesses the properties of a resin. 



Muriatic acid acts but slightly, as the guaiacum soon 

 melts into a blackish mass, which is not acted upon. 



When guaiacum is distilled, 100 parts of it yielded to 

 Mr Brande the following products : 



Acidulous water 5.5 



Thick brown oil 24-.S 



Thin empyreumatic oil 30.0 



Charcoal 30.5 



Gases, consisting of carbonic acid 1 

 and carbureted hydrogen . . . .J 





9.5 



100.0 



The coal when incinerated left three grains of lime, 

 but no alkaline substance. 



SECT. XXV. Of Balsam*. 



The term balsam or balm was originally confined to a 

 thick fragrant juice obtained from the amyrit gileaden- 

 sit, and afterwards applied by chemists to all substances 

 which possess the same degree of consistence and a strong 

 smell, whether natural or artificial. Bucquet restricted 

 the term to those resinous-like substances which yield 

 benzoic acid when heated. This new meaning of the 

 word, which has been adopted by chemists in general, 

 lias introduced into the class of balsams several substan- 

 ce* which were formerly considered as resins. The word 

 hriUam originally implied a substance possessing a certain 

 degree of fluidity; but now there are two classes of bal- 

 sams; the one fluid, and the other solid and brittle. 



A balsam, then, is a substance which possesses the ge- 

 neral properties of a resin ; but which, when heated or 

 digested in acids, yields a portion of benzoic acid. Che- 

 mist*, in general, have considered them as combinations 



of a resin with benzoic acid; but Mr Hatchett ha: 



made it probable, that the acid is formed at the time ot EiaininS- 



its separation. 



They are insoluble in water ; but when boiled in that 

 liquid often ^ive out a portion of benzoic acid. Alco- 

 hoi and ether dis-'olve them readily. The strong acids propertied 

 likewise dissolve tht m ; and during the solution a portion 

 of benzoic acid is separated. Nitric acid, in some cases , 

 evolves likewise traces of prussic acid. The alkalies act 

 upon them nearly as on the resins. They may be divi- 

 ded into two classes ; namely, liquid and solid balsams. 



1. Liquid Balsams. 



The liquid balsams at present known are four in num- Liquid 

 ber; namely, balsams, 



1. Copaiva. 3. Peru. V1Z- 



2. Tolu. 4. Styrax. 



1. Copaiva. This balsam is obtained from the copai- Copaiva, 

 fera afficinalis, a tree which grows in South America, 



and some of the West Indh Islands. It exudes from 

 incisions made in the trunk of the tree. The juice thus 

 obtained is transparent, of a yellowish colour, an agree- 

 able smell, a pungent taste, at first of the consistence of 

 oil, but it gradually becomes as thick as honey. Its 

 specific gravity is 0.950. When mixed with water and 

 distilled, there comes over with the water a very large 

 quantity of volatile oil. The residuum consists of two 

 substances ; namely, the watery portion, and a greyish 

 yellow substance, lying at the bottom of the vessel, 

 which, on exposure to the air, drie?, and becomes brittle 

 and transparent. When heated it melts, and possesses 

 the characters of a resin. When distilled it yielded a 

 yellowish thick oil, some acidulous thick water, and a 

 gas, one-sixth of which was carbonic acid, and the re- 

 mainder seemed to possess the characters of olefiant gas. 

 From these facts, which have been long known, it was 

 concluded, that copaiva is a compound of a resin and a 

 volatile oil, which passes over at a heat inferior to that 

 of boiling water ; but the experiments of Schonberg 

 have rendered it much more probable, that the balsam is 

 decomposed when distilled along with water, and that 

 both the oil and resin are new products. 



Whether this balsam yields benzoic acid has not beeu 

 ascertained. Its properties are rather against the pro- 

 bability of its doing so. Indeed it bears a striking re- 

 semblance to turpentine in many respects, and ought, 

 along with it, to constitute a class of bodies intermediate 

 between volatile oils and resins, to which the name of tvr. 

 penlincs might be given. 



2. Balsam of Tolu. This substance is obtained from the Balsam of 

 tolui/era Lalsamum, a tree which grows in South Ame- tolu, 

 rica. The balsam flows from incisions made in the bark. 



It comes to Europe in email gourd shells. It is of a red- 

 dish brown colour, and considerable consistence ; and 

 when exposed to the air, it becomes solid and brittle. Its 

 smell is fragrant, and continues so even after the balsam 

 has become 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 sublimrs, if the distillation be continued. 



3. Balsam of Peru. This substance is obtained from the Balaam of 

 myroxylan peruifernm, which grows in the warm parts of i * eru 

 South America. The tree is full of resin, and the bal- 



sam 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 the filter reddeng 

 vegetable blues, and deposits crystals of btiizoic acid on 

 cooling. The water contains no other substance. When 



