DESTRUCTIVE DISTILLATION OF ANIMAL MATTERS. 589 



Carbon, 



Hydrogen, 



Silver, 



Oxygen, 



Experiment. 





Calculation. 





28-30 



28-71 



c l0 



50 



4-34 



4-31 



H 9 



9 



51-94 



51-67 



Ag 



108 



... 



15-31 



° 4 



32 



100-00 209 



which corresponds completely with the valerianate of silver. The second precipi- 

 tate was manifestly a mixture, and gave variable quantities of silver, generally 

 about 2 per cent, under that required by the valerianate. But the third precipi- 

 tate consisted of propionate of silver, as shown by the subjoined analyses: — 



I. 5-002 grains of the third precipitate gave 2993 grains silver. 

 II. 4-796 ... another preparation gave 3-848 



Experiment. 



c 



alculation. 





19-89 



Ce 



36 



2-76 



H 5 



5 



59-66 



Ag 



108 



17-69 



O* 



32 



I. II. Mean. 



Carbon, 

 Hydrogen, . 



Silver, . . 59-83 59-38 59-50 



Oxygen, 



100-00 181 



It thus appears that the crude pyrrol contained a small quantity of some sub- 

 stances yielding valerianic and propionic acids when acted on by potash. The 

 exact nature of these compounds it was impossible to determine, as their quantity 

 was extremely minute, and the silver salts obtained from a very considerable 

 quantity of pyrrol, were no more than sufficient for the analyses just detailed. 



The fragrant pyrrol separated from the potash solution by distillation is trans- 

 parent and colourless, when freshly prepared, but acquires a brown colour by 

 exposure to the air. Its taste is hot and pungent, and its smell pleasant and 

 etherial, and recalls that of chloroform. It is sparingly soluble in water, but 

 readily in alcohol, ether, and the oils. It is insoluble in alkaline solutions, but 

 the acids dissolve it, although not very rapidly. Its specific gravity is 1-077, and 

 it boils at 271°. It gives the remarkable reaction on fir-wood described by 

 Runge in a very powerful manner. The reaction is best obtained by dipping a 

 piece of fir-wood in concentrated commercial hydrochloric acid, and holding it 

 near a vessel containing pyrrol, or in a current of its vapour ; a pale pink colour 

 immediately makes its appearance, and gradually deepens to an intense carmine. 

 All kinds of fir-wood do not produce the reaction equally well, and it appears to 

 depend in some way upon the resin, for if fir saw-dust be extracted by alcohol 

 or ether, and bits of cotton or linen cloth dipped in the solution, they acquire the 

 property of becoming red, when exposed to pyrrol vapour, after having been 

 moistened with hydrochloric acid, although the colour is by no means so brilliant 



