210 PROFESSOR T. ANDERSON ON THE PRODUCTS OF THE 



bination of two molecules of pyridine, and hence the name of dipyridine which I 

 have applied to it. 



Salts of Dipyridine. — Though dipyridine is not a very powerful base, it gives 

 a number of salts, most of which crystallise well, though some of them are not 

 easily obtained of definite composition. 



Hydrochlorate of Dipyridine. — This salt is best obtained by adding a slight 

 excess of hydrochloric acid to the aqueous solution of the base and evaporating 

 to crystallisation ; the crystals, after being pressed and recrystallised from water, 

 are sufficiently pure for analysis. They are flat needles readily soluble in water, 

 especially when hot — insoluble in ether. The salt is very apt to retain hydro- 

 chloric acid, and it is advisable to heat it to 130° for analysis. 



f 0-6104 gramme of the hydrochlorate gave 

 \ 0-7633 ... iodide of silver. 



Carbon, 

 Hydrogen, 

 Nitrogen, 

 Chlorine, 



100-00 231 



Sulphate of Dipyridine. — Dipyridine is added in slight excess to dilute sul- 

 phuric acid, and this fluid is evaporated nearly to dryness ; on cooling, crystals of 

 the sulphate are deposited ; they are washed with alcohol, in which they are scarcely 

 soluble, and again crystallised from water. It is thus obtained in needle-shaped 

 crystals, which deliquesce in moist air. One determination of sulphuric acid 

 was made of a specimen of this salt dried in vacuo over sulphuric acid, which 

 gave 26-85 per cent, of S0 3 . This would correspond with a salt containing two 

 molecules of water of crystallisation with the formula C ]0 H 10 N 2 H 2 SO 4 + 2H 2 0. 

 which requires 27 39 per cent. 



Nitrate of Dipyridine is obtained by adding a slight excess of nitric acid to 

 solution of dipyridine, evaporating on the water-bath and recrystallising. It 

 forms pale yellow needles of moderate solubility in water. When exposed for 

 some time to a temperature of 100°, it acquires an orange colour, but is not 

 sensibly decomposed. A combustion of this salt gave 



periment. 



Calculation. 







51-94 



C !0 



120 





5-19 



H 12 



12 





12-13 



N 2 



28 



30-93 



30-74 



ci 2 



71 



I. . 



C 0-5162 gramme of the nitrate gave 

 { 0-7915 ... of carbonic acid, and 

 I 0-1820 ... of water. 



Experiment. 



Calculation. 





Carbon, 

 Hydrogen, 

 Nitrogen, 

 Oxygen, 



41-81 

 3-92 



42-25 



3-92 



20-38 



3345 



H 12 



o 6 



120 

 12 

 56 

 96 



10000 284 



