576 PROFESSOR ANDERSON ON THE PRODUCTS OF THE 
Experiment. Calculation. 
I. Il. 
Carbon, 4 3 . 14:84 Aan 14:32 Cra 60 
Hydrogen, . 5 ; 1:89 a 1:43 Hi, 6 
Nitrogen, . - : 500 SF 3°34 N 14 
Chlorine, emul aie +: 33:90 Cl, 142 
Gold, = : . 46°80 46:62 47-01 Au 197 
100-00 419 
Corresponding with the formula C,,H,N HCl Au Cl,. 
When pyridine is added to a moderately dilute solution of sulphate of zine 
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 fiuid 
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 
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