o74 PROFESSOR ANDERSON ON THE PRODUCTS OF THE 
These experimental results are somewhat in excess of the theoretical density ; 
but this is in all probability due to the presence of a small quantity of picoline, 
which, from the nature of the experiment, must necessarily remain in the balloon, 
and tend to produce an appreciable error in the density, even when its quantity 
is far too minute to be distinguished by an ordinary analysis. The specimen of 
pyridine used in these experiments had been purified with great care, and its 
platinum salt gave results corresponding completely with theory. 
Salts of Pyridine. 
Hydrochlorate of Pyridine.—When hydrochloric acid is saturated with pyridine, 
and the solution evaporated on the water bath, the salt remains in the form of a 
thick syrup, so long as it is warm, but on cooling, crystals slowly make their 
appearance, and gradually shoot through the fluid, which is eventually converted 
into a hard radiated mass. The salt deliquesces when exposed to moist air, and 
sublimes unchanged at a high temperature. It is very soluble in alcohol, but less 
so than in water. It is insoluble in ether. 
Hydriodate of Pyridine-—This salt crystallizes in tabular crystals, readily 
soluble both in water and alcohol, but not deliquescent. An analysis of the salt 
in an impure state will be afterwards given. 
Hydrobromate of Pyridine.—A deliquescent salt, obtained on evaporation as 
a mass of acicular crystals. 
Nitrate of Pyridine.—This salt is easily obtained by mixing nitric acid and 
the base. Ifthe acid be concentrated, and the base dry, or nearly so, much heat 
is produced, and the mixture rapidly solidifies into a mass of short needles, which, 
when expressed between folds of blotting-paper, closely resembles loaf-sugar. 
The salt is purified by solution in hot water, or better in boiling spirit. On cooling, 
it is deposited from the latter solution in fine needles, which can easily be obtained 
an inch long, even when operating on a very small scale. Sometimes it appears 
in short thick prisms. It is not deliquescent, but is extremely soluble in water, 
less so in alcohol, and not at all in ether. When heated in a retort it melts; and if 
the temperature be raised very gradually it sublimes as a white woolly mass; but, 
if briskly heated, it distils in the form of a thick oily fluid, which solidifies in the 
neck of the retort to a mass of acicular crystals. If the heat be carefully regu- 
lated it sublimes without undergoing the least change, but if rapidly distilled, 
a small quantity of red fumes are occasionally seen. Heated on a platinum knife 
it catches fire and burns with great brilliancy, and a rapidity almost approaching 
to deflagration. Analyses made on different preparations gave the following 
results :— 
9-238 ... carbonic acid and 
5-954 grains of nitrate dried at 212° gave 
I 
2°358 ... Water. 
