Ift 



C H E M I S T R Y. 



8. Ammoniac. This substance ia brought from the 

 East Indie*. Nothing certain it known concerning the 

 plant which yields it ; though from analogy it has been 

 suspected to be a species of ferula. It i* in small pieces, 

 agglutinated together, and has a yellowish white colour. 

 Its smell is somewhat like that of galbanum, but more 

 pica jail t. Its taste is a nauseous sweet, mixed with bit- 

 ter. It does not melt. Water dissolves a portion of it ; 

 the solution is milky, but gradually lets fall a resinous 

 portion. More than one half is soluble in alcohol. This 

 portion is a resin. 



According to the analysis of Braconnot, ammonia is 

 composed of the following ingredients : 

 70.0 resin 

 18.4 gum 



4.4 glutinous matter 

 6.0 water 

 1.2 loss 



100.0 



Wlibanum. 3. OLbanum. This substance is obtained from the 

 Bontallii: thurifera, and is chiefly collected in India. It 

 is the frankincense of the ancients. It is in transparent 

 brittle masses about the size of a chesnut. Its colour 

 is yellow. It has a bitterish nauseous taste ; and when 

 burnt diffuses an agreeable odour. Alcohol dissolves 

 three fourths of it, and water about throe-eighths. 



Aafcetida. 4. Ataftttida. This substance is obtained from the 

 ferula tuafactida, a perennial plant, which is a native of 

 Perua. When the plant is about four years old, its 

 roots are dug up and cleaned. Their extremity being 

 then cut off, a milky juice exudes, which is collected. 

 Then another portion is cut off, and more juice exudes. 

 This is continued till the roots are exhausted. The juice 

 thus collected soon hardens and constitutes asafatida. 

 It comes to Europe in small grains of different colours, 

 whitish, reddish, violet, brown. It is pretty hard, but brit- 

 tle. Its taste is acrid and bitter ; its smell strongly alii- 

 aceous and fetid. Alcohol dissolves about three-fourths 

 of this substance ; and water takes up nearly one-fourth 

 if applied before the spirit. 



scanunony. 5. Scammow/. This substance is obtained from the 

 inn'olvulus tcantmonia, a climbing plant which grows 

 in Syria. The roots, when cut, yield a milky juice. 

 This, when collected and allowed to harden, constitutes 

 scammony. Colour dark grey or black. Smell peculiar 

 and nauseous : taste bitter and acrid. With water it 

 forms a greenish-coloured opaque liquid. Alcohol dis- 

 solves the greatest part of it. It is usually mixed with 

 the expressed juice of the root, and frequently also with 

 other impurities, which alter its appearance. In medi- 

 cine it operates as a strong cathartic. 



Opoponax. & Opoponax. This substance is obtained from the 

 pattinaca opopontuc, a plant which is a native of the 

 countries round the Levant. The gum resin, like most 

 others, is obtained by wounding the roots of the plant. 

 The milky juice, when dried in the sun, constitutes the 

 opoponax. It is in lumps of a reddish yellow colour, 

 and white within. Smell peculiar. Taste bitter and 

 acrid. With water it forms a milky solution, and about 

 one-half of it dissolves. Alcohol acts but feebly. 



Ganbogc. 7. Gamboge or Gumgult. This substance is obtain- 

 ed from the ttalagmitit gambogioides, a tree which grows 

 wild in the East Indies. In Siam it is obtained in drops 

 by wounding the shoots ; in Ceylon it exudes from 

 wounds in the bark. It is brought to Europe in large 

 cake*. Its colour is yellow ; it it opaque, brittle, and 

 breaks vitreous. It has no smell, and very little taste. 

 With wattr it forms a yellow turbid liquid. Akohol 







My: 



dissolves it almost completely ; and when mixed wif; ; 

 water becomes turbid, unless the solution contains am. 

 monia. 



Braconnot analyzed it, and found it composed of one 

 part of a gum which possessed the properties of cherry 

 tree gum, and four parts of a redditii brittle resin, which 

 possessed the characteristic properties of the resins. 



8. Myrrh. The plant from which this substance is 

 obtained is unknown. According to Bruce, it belongs 

 to the genus of mimosa. It grows in Abyssinia and 

 Arabia. It is in the form of tears. Colour reddish yel- 

 low ; when pure somewhat transparent, but it is oft or; 

 opake. Odour peculiar. Taste bitter and aromatu. 

 Docs not melt when heated, and burns with difficulty. 



From the analysis of Braconnot it appears that myrrh 

 is composed of about 



23 resin 

 77 gum 



100 



The resin is reddish, has a bitter taste, and the pe- 

 culiar odour of myrrh. The gum differs in its proper- 

 ties from every other gummy substance hitherto exa- 

 mined. It has a dark brown colour ; is at first soluble 

 in water, but by boiling the liquid, or by exposing the 

 gum to heat, it requires cohesive properties, and be- 

 comes insoluble in water. When distilled it yields am- 

 monia, and when dissolved in nitric acid, azotic gas is 

 disengaged. 



It deserves attention, that the gum resins, when sub- 

 jected to destructive distillation, yield all of them a por- 

 tion of ammonia ; a proof that they all contain azote. 

 In this respect they agree with gum and extractive. 



SECT. XXVIII. Of Cotton. 



Cotton is a soft down which envelopes the seeds of Cotton. 

 various plants, especially the different species of gossy- 

 pium, from which the cotton of commerce is procured. 

 These plants are natives of warm climates ; grow wild in 

 Asia, Africa, and America, within the tropics ; and 

 are cultivated in the East and West Indies. 



Though no correct chemical investigation of the pro- 

 perties of cotton has hitherto been made, yet as its obvi- 

 ous qualities distinguish it sufficiently from every other 

 vegetable substance, we must consider it as a peculiar 

 vegetable principle ; and it has been introduced here, in 

 hopes that some person or other will be induced to exa- 

 mine its nature in detail. The following arc the parti- 

 culars at present known. 



This substance is in threads differing in length and Propcrtiri 

 fineness. No asperities can be discovered on the surface at present 

 of these threads ; but if Lewenhoeck's microscopical 

 observations are to be trusted, they are all triangular, 

 and have three sharp edges. Cotton differs considerably 

 in colour ; but when bleached it becomes of a fine white. 



Cotton is tasteless and destitute of smell. It is com- 

 pletely insoluble in water, alcohol, ether, and oils, and 

 in all the vegetable acids. 



The diluted alkaline leys have no perceptible action 

 on cotton ; but when very strong they dissolve it if as- 

 sisted by a sufficient degree of heat. The new products 

 obtained by this solution have not been examined. 



Cotton combines readily with tannin, and forms a yel- 

 low or brown compound. Hence the infusion of galls, 

 and other astringent substances, is often used as a mor- 

 dant for cotton. 



Nitric acid decomposes cotton when assisted by heat, 

 and oxalic tcid is formed ; the other products have not 



