ESTIMATION OF NICOTINE 39 



Twenty grams or so of tobacco or tobacco leaves are 

 dried at a temperature of 60° and are finely ground 

 while still warm, preferably in a hand-mill. Ten grams of 

 the powder are placed in a small beaker and 10 c.c. of 

 alcoholic-soda solution added.^ The object of this 

 addition of caustic soda is to liberate the free nicotine 

 from any salt, such as malate, citrate, etc., in which it 

 may exist combined in the leaves. The mixture is 

 well stirred with a spatula, and when homogeneous 

 is placed in a filter-paper cartridge and extracted with 

 ether in a Soxhlet extractor for five hours. 



The ether is then distilled from the extract on the 



water-bath, and the residue containing all the nicotine 



taken up with 50 c.c. of a -4 per cent, aqueous solution 



of caustic soda. The green liquid is transferred to a 



500 C.C. flask and distilled in steam, with very efficient 



condensation (Fig. 10). The distillation is carried on 



till about 400 c.c. have collected in the receiver, when 



all the nicotine should have passed over. The distillate 



N 

 is titrated with — HgSO^, using cochineal as indicator, 



and from the amount of the standard acid used the 



percentage of nicotine in the leaves can be readily 



calculated. 



N 

 One c.c. — H2SO4 is equivalent to -081 gram nicotine. 



Nicotine, CioHi4N2, is a colourless liquid, and is one of the few 

 alkaloids containing no oxygen. It is strongly loevorotatory [<2]d = 

 - 162°, boils at 247° C, and is slowly oxidised by air to a dark liquid 



1 The alcoholic-soda solution is prepared by dissolving 6 grams 

 caustic soda in 40 c.c. distilled water and 60 c.c. 90 per cent, 

 alcohol. 



Ten c.c. of this solution contains caustic soda more than 

 sufficient in amount to liberate all the combined nicotine present in 

 10 grams of leaves containing up to 10 per cent, nicotine. 



