554 Royal Society : — 



to a moderately concentrated, gently warmed solution of the chloride, 

 a splendid bright orange-yellow platinum-salt separates, on cooling, 

 in well-formed prisms, generally aggregated to triangular stars. The 

 salt is difficultly soluble in cold water ; boiling water decomposes it. 

 At 100° this salt retains one equivalent of water, which can be ex- 

 pelled, although with difficulty, at higher temperatures. Numerous 

 analyses of this beautiful compound have established the formula 



C 20 H al N 3 , 3 H CI, 3 Pt Cl 2 + H 2 O. 



Nitrate of Leucaniline. — Well-formed white needles, soluble in 

 water and alcohol, insoluble in ether. The salt is rather difficultly 

 soluble in nitric acid. When dried in vacuo this salt contains 



C 20 H 21 N 3 ,3HNO 3 + H 2 O, 



I have not succeeded in separating the water of crystallization, the 

 salt being decomposed at 100°. 



The salts of leucaniline are, in general, well crystallized. They 

 are all very soluble in water, and precipitated from the aqueous solu- 

 tion by the addition of the respective acids. The sulphate crystallizes 

 readily. I have submitted leucaniline to the action of disulphide of 

 carbon, chloride of benzoyl, and several other agents. In all these 

 cases new compounds are generated, some of them remarkable for 

 their crystallizing power. The study of these substances does not 

 belong to the present inquiry; I shall return to them in a future 

 communication, in which I propose to examine the constitution of 

 rosaniline and leucaniline, and their derivation from aniline. The 

 object of the present Note was only to fix the composition of the two 

 new bases, and their mutual relations to each other. This relation, 

 as will be obvious by a glance at their formulae, is of the simplest 

 kind. In the anhydrous condition the two substances respectively 

 contain, 



Rosaniline C 20 H 19 N 3 . 



Leucaniline C 20 H 21 N 3 . 



Leucaniline differs from rosaniline simply by containing two equi- 

 valents of hydrogen more. The two bases hold to each other the 

 relation which obtains between blue and white indigo ; 



Blue indigo C 16 H 10 N 2 2 . 



White indigo C 16 H 12 N 2 2 . 



Leucaniline, as might have been expected, is readily reconverted 

 into the red colouring matter by oxidizing agents. The reaction suc- 

 ceeds with peroxide of barium, perchloride of iron, or chromate of 

 potassium. On gently heating the colourless solution of the chloride 

 with one of these reagents, the liquid at once reassumes the splendid 

 colour of the rosaniline-salts. An excess of the oxidizing agents is, 

 however, to be avoided, lest the action should go too far and the re- 

 generated compound be converted into further products of oxidation. 

 Both rosaniline and leucaniline, when submitted to protracted ebulli- 

 tion with highly oxygenated compounds, yield a brown amorphous 

 powder, the composition of which remains at present unknown. 



The two bases which I have described in the preceding paper are 

 the prototypes of two series of homologous colouring matters which 



