[TINGLE-FERGUSON] AQUEOUS SOLUTIONS OF NICOTINE 23 
We wished to make, if possible, a further determination by some 
method which did not involve the direct weighing of such an unstable 
and hygroscopic substance as nicotine. The only well-crystallised 
salt of this base which seemed suitable for the purpose was the “bi- 
tartrate’”’ described in Beilstein’s Handbuch as having the formula 
CoeliaeN>.  2C4H: 0," 2:10; We prepared a salt from nicotine 
and tartaric acid which we re-crystallised from alcohol with the 
addition of a little ether, and which answered to the description of the 
above compound, but appears to have a different composition. Un- 
fortunately we had no facilities for making an ultimate analysis. A 
volumetric determination of the tartaric acid present showed 63-75%, 
corresponding closely to the 63-69% demanded by the formula 
2CiHuNe + 4C4H6O6 ‘ HeO. No direct determination of water 
of crystallisation was possible, as the salt melts and decomposes at a 
somewhat low temperature. 
A sample of this salt, weighing 10 grammes, was dissolved in a 
100 cb.c. graduated flask, the solution was made strongly alkaline 
with sodium hydroxide, and an excess of calcium chloride solution was 
added. The whole was made up to 100 cb.c. after standing overnight, 
and the solution was filtered through a dry paper. On examination 
in the polarimeter the filtrate was found to give a negative rotation of 
15-9 sugar scale divisions. The formula we suggest for this tartrate 
corresponds to 34-39% of nicotine. Our sample would then contain 
3-439 grammes of the base, and according to this determination one 
sugar scale degree = 0-216 gramme of nicotine in 100 cb.c. Uncer- 
tainty as to the composition of the salt, and the large amount of 
precipitate formed in the solution, alike render this determination of 
less value than we had hoped, but it is in sufficiently good agreement 
with the preceding ones to strengthen our confidence in their accuracy. 
We satisfied ourselves that the tartrate remaining in solution 
was too small to have any effect on the rotatory power by the following 
experiment. A solution was made of 7:2 grammes of ‘Rochelle 
Salt” and 2-8 grammes of sodium hydroxide in 20 cb.c. of water. 
To this was added 30 cb.c. of a saturated solution of calcium chloride. 
The mixture was allowed to stand overnight, filtered and examined 
in the polariscope. It showed no rotatory power. 
Discussion of Results. 
It has been stated by Popovici (Zeit. physiolog. Chem. 13-445) 
that the nicotine content of a solution is not proportional to its rota- 
tory power. He gives a table showing the relation between the 
- percentage of nicotine in a solution and the rotatory power as deter- 
