132 THE SIMPLER NATURAL BASES 



Indolethylamine. 



The free base, on recrystallisation from a mixture of alcohol and 

 benzene, forms long colourless needles, melting at 145-146. It is 

 readily soluble in alcohol and in acetone, but is almost insoluble in 

 water, ether, benzene and chloroform. It gives very intensely Hopkins 

 and Cole's reaction with glyoxylic and sulphuric acids, characteristic of 

 tryptophane ; the bluish-violet coloration is still obtainable with the 

 base in a dilution of I : 300,000. Unlike tryptophane, aminoethyl- 

 indole is not coloured by bromine water, nor does it react with 

 triketohydrindenehydrate. 



The hydrochloride, C 10 H 12 N 2 . HC1, forms thin prisms melting at 

 246 and is soluble in about 12 parts of water at 18. 



The/zmzte is the most characteristic salt of the base. It has the 

 composition C 10 H 12 N 2 . C 6 H 3 O 7 N 3 and is obtained by adding a cold 

 saturated solution of picric acid to a solution of the hydrochloride in 

 water ; the mixture at once becomes turbid and orange-red in colour, 

 and dark red crystals, consisting of fern-like aggregates of needles or 

 prisms (resembling in shape those of ammonium chloride) rapidly 

 separate. This picrate is almost insoluble in water and very sparingly 

 so in alcohol and most organic solvents, but dissolves readily in 

 acetone ; it melts and decomposes at 242-243. 



The picrolonate crystallises readily from hot water in deep chrome- 

 yellow prisms melting at 231. 



The monobenzoyl derivative of 3-/3-amino-ethylindole is difficult to 

 crystallise, and therefore not suitable for characterising the base ; it 

 forms stout prisms melting at 137-138. 



-Iminazolyl-ethylamine. 



Bacterial Preparation. 



Ackermann [1910, l] dissolved 49 grm. of histidine hydrochloride 

 in 4 litres of water, added 10 grm. of Witte peptone, 20 grm. of 

 glucose, a few drops of magnesium sulphate and sodium phosphate 

 solutions, and excess of calcium carbonate to keep the reaction 

 alkaline. After inoculation with putrid pancreas the solution was 

 kept fifty-two days at 35. It yielded 6r6 grm. of iminazolyl- 

 ethylamine dipicrate which is 42 per cent, of the theoretical ; a very 

 small quantity of iminazolyl-propionic acid was also formed. 



When working with small quantities of histidine and pure cultures 

 of certain bacteria one can occasionally obtain solutions of which the 

 physiological activity indicates an almost complete conversion. How- 



