Iff* 



CHEMISTRY. 



dutillcd with water, it yields a very small quantity of 

 rrdduh limpid nil. 



Nature *' ^'y rax - Thii '* emifluid juice, said to be ob- 



i from the liquidambar fti/rariflita, a tree which 

 growi in Virginia, Mexico, and sume other parts of Ame- 

 rica. It is prepared, according to Mr IVtiver, in the 

 island of Cobross in the Red Sea, from the hark of a 

 tree called rosa tiallos. by the natives, and considered 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 caiks. Its colour ii 

 greenish, its taste aromatic, and its smell agreeable. It 

 u easily volatilized by heat. When treated with water, 

 benzoic acid is dissolved. It is totally soluble in alcohol, 

 except the impurities. When exposed to the air, it be- 

 comes 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 carbu- 

 reted hydrogen. The charcoal is light, and contains 

 some oil. 



2. Solid Balsams. 



Solid bil- The solid balsams at present k nown are only three 

 tarn*, vi. in number ; namely, 



1. Benzoin. 



2. Storax. 



3. Dragon's blood. 



1 . Benzoin. This substance is the produce of the 

 styrax benzoc, a tree which grows in Sumatra, fee. Ben- 

 zoin is obtained from this tree by incision ; a tree yield- 

 ing 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 sometimes in the 

 form of a brown substance not unlike common rosin. 

 It has a very agreeable smell, which is increased by heat- 

 ing the benzoin. It has little taste. Its specific gra- 

 vity is 1.092. 



Cold water has very little effect on benzoin, but boil- 

 ing water takes up a portion of bcn/.oic acid. 



Alcohol dissolves it when assisted by a gentle heat, 

 and forms a deep yellow solution inclining to reddish 

 brown. When this solution is diluted with water, the 

 benzoin precipitates in the form of a white powder. 



Ether dissolves benzoin with facility, and the solution 

 with re-agents exhibits the same phenomena as the alco- 

 holic. 



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 separate. 



Sulphuric acid dissolves benzoin, while benzoic acid 

 sublimes ; the solution is at first a deep red. By conti- 

 nuing the digestion, a portion of artificial tannin is form- 

 ed, and the charcoal evolved amounts to 0.48 of the 

 benzoin dissolved. 



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. Am- 

 monia likewise dissolves benzoin sparingly. 



When Mr Brande exposed 100 grains of benzoin in a 

 retort to a heat gradually raised to redoes;, the products 



. 

 N itur*. 



Benzoic acid S.ft 



Anduluus water 



Butyraceous and empyrcumatic oil . . I.IMI 



Charcoal '^.0 



Carbureted hydrogen and carbonic acid . :!.5 "Tr* 



JOO.O 



2. Siorax. This is the most fragrant of ail tl:e bal- Storax, 

 sams, and is obtained from the slyrajc ttfflcinalit, a tree 

 which grows in the Levant, and it is said alto in Italy. 

 Sometimes it is in the state of red tears ; and this is caid 



to be 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 jcolour. This is more 

 fragrant than the other sort, though it contains a consi- 

 derable mixture of saw-dust. It dissolves in alcohol. 

 When distilled with alcohol or with water, scarcely any 

 oil is obtained. When distilled by the naked fire, it 

 seems, from the experiments of Neumann, to yield the 

 same products as benzoin. 



3. Dragon' t blood. This is a brittle substance of a Dragon ' 

 dark red colour, which comes from the East Indie*, blood. 

 There are two sorts of it ; one 111 small oval drops or 



tears of a fine deep red, which becomes crimson when 

 the tears are reduced 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 dracaena draco and the pterocarput draco 

 are also said to furnish it. 



Dragon's blood is brittle and tasteless, and has no sen- 

 sible smell. Water does not act upon it, but alcohol 

 dissolves the greatest part, leaving a whitish red sub- 

 stance, partially acted upon by water. The solution has 

 a fine deep red colour, which stains marble, and the stain 

 penetrates the deeper the hotter the marble i?. It dis- 

 solvos also in oils, and gives them a deep red colour. 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 becomes soluble in water, and it ac- 

 quires a balsamic odour. On adding muriatic acid to 

 the solution, a red resinous substance is precipitated, and 

 slight traces of benzoic acid only . become perceptible. 

 Nitric acid acts upon it with energy, changes it to a deep 

 yellow, a portion of benzoic acid is sublimed, and a 

 brown mass remains soluble in water, and possessing the 

 properties of artificial tannin. 



SECT. XXVI. Of Caoutchouc. 



About the beginning of the 18th century, a substance Canut- 

 called caoutchouc was brought as a curiosity from Amc- chouc. 

 rica. It was soft, wonderfully elastic, and very combus- 

 tible. The pieces of it that came to Europe were usually 

 in the shape of bottles, birds, &x. This substance is very 

 much used in rubbing out the marks made upon paper 

 by a black lead pencil, and therefore in this country it is 

 often called Indian rubber. 



It is now known, that there are at least two trees in 

 South America from which caoutchouc may be obtain- 

 ed ; the tucvca caoutchouc, and the jalropna elastica ; 

 and it is exceedingly probable that it is extracted also from 

 other species of hievea imdjattopka. Several trees like- How ofc- 

 wise which grow in the East Indies yield caoutchouc ; 

 the principal of these are, thejicus indica, thearlocaiput 

 intrerifolta, and the urceola elastica. 



Whtn any of these plants are punctured, there exudes 

 from it a milky juice, which, when exposed to the air, 

 gradually lets fall a concrete substance, which is caout- 

 chouc. 



