[TINGLE-FERGUSON] AQUEOUS SOLUTIONS OF NICOTINE 2 
Effect of Free Alkali and Alkali Salts on the Rotatory Power of 
Nicotine Solutions. Effect of Evaporation in the Presence of Sulphuric 
Acid. 
Experiment 1. An aqueous solution of nicotine was prepared, its 
strength being approximately 0-5%. To 100 cb.c. of this solution a 
slight excess of sulphuric acid was added. The product was evaporated 
to small bulk on the water bath. It was then cooled, and potassium 
hydroxide solution was added till the whole was strongly alkaline. 
The mixed solution was diluted to the original volume (100 cb.c.) 
and was compared in the polarimeter with the original nicotine solu- 
tion from which it had been produced. 
Both liquids gave a rotation of — 2-6 sugar scale divisions, show- 
ing that the treatment detailed had had no effect on the rotatory 
power. 
Experiment 2. To 50 cb.c. of an aqueous solution of nicotine 
(approximately 20%) an excess of sulphuric acid was added. 
The mixture was evaporated to small volume, partly neutralized, made 
up to 50 cb.c. again, and 25 cb.c. of this solution was again 
evaporated with an excess of sulphuric acid. The concentrated solu- 
tion was made alkaline and diluted to 50 cb.c. 
The original solution read — 8-6 and the final product — 4-3 
in the polarimeter. The latter figure absolutely agrees with what 
was calculated on the assumption that the rotary power would be 
proportional to the dilution and independent of the presence of salts, 
of alkali, and of repeated evaporation with acid. 
Experiment 3. To 200 cb.c. of a nicotine solution (approximately 
0.7%) an excess of sulphuric acid was added. It was then evaporated, 
made alkaline, and the volume made up to 100 cb.c. 
The concentrated solution so obtained gave a reading — 6-65 
in the polarimeter, while the original solution from which it was 
prepared read — 3-3. Agreement between the figures expected and 
obtained was therefore again within the limit of error. 
Determinations of the Rotatory Power of Nicotine in Dilute Aqueous 
Solution. The nicotine purchased for the determination of this 
constant was Mercks’ “C.P.” article. We found it grossly contamin- 
ated not merely by the presence of oxidation or polymerisation 
products such as we expected, but also by the presence of some high- 
boiling hydrocarbon oil, which had probably been used as a solvent 
and not completely removed. 
Preparation of Pure Nicotine. The above impure product was 
dissolved in dilute hydrochloric acid. The hydrocarbon was removed 
by shaking with chloroform and the aqueous layer was transferred 
