576 PROFESSOR ANDERSON ON THE PRODUCTS OF THE 





Experiment. 





Calculation. 







I. II. 



""" 





~~^ 



Carbon, 



14-84 



1432 



C 10 



60 



Hydrogen, 



Nitrogen, 



Chlorine, 



1-89 



1-43 



3-34 



33-90 



H 5 



N 



Cl 4 



6 



14 



142 



Gold, 



. 46-80 46-62 



47-01 



Au 



197 



10000 419 



Corresponding with the formula C 10 H 5 N HC1 AuCL. 



When pyridine is added to a moderately dilute solution of sulphate of zinc 

 in considerable excess, oxide of zinc is precipitated. And if a quantity of hydro- 

 chloric acid insufficient to neutralize the pyridine be then added, the fluid instantly 

 becomes clear ; but if it be stirred briskly, it rapidly fills with an abundant crys- 

 talline precipitate of a double salt. The salt dissolves with facility in boiling 

 water, and is deposited, on cooling, in long, brilliant needles. Sulphate of cop- 

 per, when treated in a similar manner, gives a pale greenish-blue precipitate, so- 

 luble in boiling water, from which it crystallizes in fine bluish needles. The salts 

 of manganese and nickel, and protoxide of iron, appear also to form double salts, 

 but they are very soluble, and have not been particularly examined. 



Products of the Decomposition of Pyridine. 



Pyridine, like all its homologues, is an exceedingly stable base, and resists the 

 action of oxidising agents. It may be boiled with the most concentrated nitric 

 acid, or with chromic acid, without undergoing decomposition ; and treatment 

 with the former acid affords an invaluable means of freeing those bases from any 

 empyreumatic matters with which they may be mixed. 



Action of Chlorine on Pyridine. — The action of chlorine on pyridine depends 

 upon the mode in which that agent is employed. When a current of the gas is 

 passed through an aqueous solution of the base it is rapidly absorbed, the fluid 

 acquires a dark brown colour, and evolves a peculiar pungent odour ; and on 

 the addition of potash, the smell of unchanged pyridine becomes apparent, while 

 a quantity of a dark brown resinous matter is separated. But if an excess of 

 pyridine be thrown into a large bottle of dry chlorine, and distributed over the 

 sides as rapidly as possible, in order to prevent rise of temperature, it remains 

 perfectly colourless, and is converted into a mass of radiated crystals. On the 

 addition of water the crystals dissolve, leaving a quantity of a snow-white amor- 

 phous powder, and hydrochlorate of pyridine is found in the solution. The 

 white powder has a faint smell, not unlike that of bleaching powder. It is inso- 

 luble in water, but dissolves in alcohol, and is precipitated again in white flocks 

 on the addition of water. When boiled for some time with water it softens, but 



