DESTRUCTIVE DISTILLATION OF ANIMAL SUBSTANCES. 211 



Double Salt with Chloride of Zinc. — This substance is prepared by adding to 

 dipyridine a mixture of hydrochloric acid and zinc chloride, and allowing it to 

 stand for some time, when small prismatic crystals are deposited. Their formation 

 is materially assisted by the addition of alcohol and ether. The compound may 

 even be obtained from the crude product, in which the dipyridine is mixed with 

 the oily base distilling along with it. For this purpose zinc chloride, along with 

 hydrochloric acid and a considerable excess of alcohol and ether, must be added 

 to the crude product, when, especially on stirring, the zinc salt deposits, and 

 can be purified by crystallisation from water. This process can even be em- 

 ployed for separating the two bases. The salt is in long white needles, soluble in 

 eight times their weight of water, less so in alcohol, and quite insoluble in ether. 

 On the addition of potassic hydrate in excess it gives the pure base in minute 

 crystals. A chlorine determination gave 



f 03 660 gramme zinc salt gave 

 105755 ... dichloride of zinc. 



Carbon, 



Hydrogen, 

 Nitrogen, 

 Chlorine, 

 Zinc, 



Experiment. 





Calculation. 







32 70 



Pu 



120 





3-27 



H 12 



12 





762 



N 2 



28 



38-90 



38-68 



4 



142 





17-73 



Zn 



65 



10000 367 



Double Salt with Nitrate of Silver.— This salt is best obtained by mixing hot 

 solutions of dipyridine hydrochlorate, and silver nitrate, the latter being in 

 excess, and at once filtering off the precipitated silver chloride. On cooling, the 

 salt is deposited in brilliant needles, of sparing solubility in water. This com- 

 pound could not be obtained of constant composition, but one specimen gave 

 35-09 per cent, of silver, while the formula C 10 H 10 N 2 (HNO 3 ) 2 (AgNO 3 ) 2 requires 

 34-61. 



Platino-chloride of Dijjyridine. — The analysis of this salt has been already 

 given. It is obtained as a crystalline yellow powder of very sparing solubility. 



Palladio-chloride of Dipyridine is obtained as an orange precipitate on 

 mixing the hydrochlorates. 



Derivatives of Dipyridine. 



Diethylo- Dipyridine. — The compounds of this base were obtained in the usual 

 manner. The ethyl-iodide is easily prepared by exposing dry dipyridine with 

 iodide of ethyl to the temperature of 100° in hermetically sealed tubes. The 

 action is complete in half an hour. It is obtained in acicular crystals, which are 

 brilliant and perfectly colourless if they have not been exposed to the air. They 

 are very soluble in water, much less so in alcohol and in ether. 



