ORGANIC CHEMISTRY 



material, and these have been utilised in further 

 experiments. The chemist, having based a con- 

 ception of the molecular structure on these analy- 

 tical methods, has endeavoured to reconstruct 

 in actual experiment the molecule of the natural 

 product from suitable fragments obtained either 

 from the substance in question or from other 

 sources. The results obtained by the use of this 

 synthetical method are remarkable. To give here 

 a complete list of nature's products which have 

 been synthesised is unnecessary, but attention may 

 be directed to the following interesting cases : 

 fats, simple sugars, tannins, uric acid, caffeine, 

 camphor, limonene (the chief constituent of oil 

 of lemon), menthol, adrenaline (the active prin- 

 ciple of the suprarenal capsules), cocaine, nicotine, 

 and such natural dyestuffs as alizarin, indigo, the 

 yellow dye of the dyer's broom, the pigment of 

 gamboge, and the colouring matters contained in 

 the petals of flowers and the skins of various fruits ; 

 all these have been synthesised. More complex 

 substances such as hasmatein, the pigment of blood, 

 and chlorophyll, the pigment found in leaves, are 

 at present under investigation ; their structures 

 have been partly resolved, and it does not seem too 

 sanguine to hope that these materials also will 

 yield to the efforts of the chemist. 



It has been explained in a foregoing paragraph 

 that these syntheses have been effected by building 



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