172 Proceedings of the Royal Irish Academy. 



soluble in boiling water than that of the previous acid. Found, 43'89 

 per cent, of silver; calculated, 43-9 per cent. 



In contact with boiling water, or in the cold in presence of even 

 highly dilute mineral acids, these two acids are rapidly resolved into 

 jnethyl- or ethyl-pyrrol and carbonic anhydride. Their solutions in 

 water below its boiling point are tolerably stable so long as they are 

 contained in smooth glass vessels ; but rough surfaces (filter paper) or 

 fine points cause rapid decomposition. They give with neutral ferric 

 chloride a red colour. 



Ethyl-dicarhopyrrolic acid. — C4II2N (CsTIs) (C00II)2 is obtained by 

 the action of large excess of alcoholic potash at 130° C, upon triethyl- 

 dicarlopyrrolamide, one of the decomposition products of ethylammo- 

 nium mucate. The potassium salt crystallizes from alcohol in long 

 needles. The acid is obtained from its aqueous solution by precipita- 

 tion with hydrochloric acid. It appears as a sandy powder, quite 

 insoluble in boiling water, and not decomposed by it. It is easily 

 soluble in alcohol and ether. By crystallization from dilute alcohol 

 it is procured in brilliant needles, which when heated do not melt, 

 but at about 250° C. are resolved into ethyl-pyrrol and carbonic 

 anhydride. 



CiHjNCC^Hs) (C00H)2 = €434^(02^5) + 2CO2 



Analysis gave the following results : — 



Found. CalcTilated. 



C = 52-26 . . . . . 52-26 



H = 5-27 . . . . . 4-91 



A" = 7-96 7-65 



The nitrogen determination was a little too high, owing to the 

 accidental employment of slightly impure soda-lime. 



The salts of this acid are mostly soluble in water. The silver 

 salt is an insoluble sandy powder. Found, 53-97 per cent. Ag : cal- 

 culated for, CiHolS'fCoHs) (COO Ag)o = 54-4 per cent. 



The acid is very slowly decomposed in the cold by concentrated 

 hydrochloric acid. Boiling dilute nitric acid dissolves it, but deposits 

 it unchanged on cooling. Strong and warm nitric acid also dissolves 

 it, but does not again deposit it on dilution. 



About two per cent, of its weight of this acid may be obtained 

 from the mucate of ethylia. 



Action of Bromine upon Pyrrol Derivatives. 



When bromine is added to a solution of ethyl-pyrrol in ether or 

 chloroform, the mixture becomes dark-coloured and gives off hydro- 

 bromic acid. The reaction takes place with greater smoothness when 

 alcohol is used as a solvent ; but the best result is attained when 

 ethyl-pyrrol is shaken with excess of bromine water, added gradually. 



