720 



ROSANILINE 



four ropes compose a -cordage 4 J inches broad and 1 inch thick, being the ordinary 

 dimensions of the grooves in the whim-pulleys round which they pass. 



Pelative Strength oj Cordage, shroud-laid. 



The above statement is the result of several hundred experiments. 



ROPE, WIRE. See WIBE ROPE. 



ROSArJXXilNE. The name given by Dr. Hofmann to a compound which plays 

 the part of a well-defined base in the formation of the aniline reds. It may now 

 bo considered as demonstrated that the aniline reds aro salts of a peculiar and 

 extremely remarkable compound, called rosaniline. See ANILINE. 



Rosaniline in the anhydrous state is represented by the formula C 40 H 19 X 3 (C" H I9 N S ), 

 and in the hydrated state, such as it assumes when isolated from its compounds, by 

 the formula C 40 H 19 N S .2HO (C">K 19 N 3 .H-O). 



It is a triamine capable of combining with one, two, and three equivalents of acid. 

 The pure aniline reds aro saline compounds of rosanilino with one equivalent of acid. 



It is very interesting that rosaniline itself, when freshly prepared, is a colourless 

 compound. It is nearly insoluble in water, slightly soluble in ammonia, moro 

 soluble in ether. When exposed to the action of the air, rosaniline becomes rapidly 

 rose-coloured, and finally of a deep red, probably in consequence of the formation of 

 a carbonate. It is a rather powerful base, forming salts, almost all of which are re- 

 markable for their beauty, and the facility with which they crystallise. 

 ' The salts containing one equivalent of acid exhibit, for the most part, in reflected 

 light, the lustrous metallic green of the wings of the rose-beetle ; in transmitted light 

 the crystals are red, becoming opaque when they acquire certain dimensions. The 

 solutions of these salts in water or alcohol possess the magnificent crimson colour 

 which characterises rosaniline-compounds. According to M. Chevreul, who, in the 

 extensive course of his memorable researches on the theory of dyeing, examined 

 the colouring-matters derived from coal-tar, the green colour reflected from the salts 

 of rosaniline is exactly complementary to the colour which these salts impart to wool 

 or silk. 



The salts with three equivalents of the stronger acids, on the other hand, are 

 yellowish-brown, both in the solid state and in solution. They are much more soluble 

 in water and alcohol than the monacid salts, which, for the most part, are compara- 

 tively sparingly soluble. 



Both classes of rosauiline salts crystallise readily, moro especially the monacid 

 compounds, some of which Mr. Nicholson has obtained in perfectly well-formed 

 crystals. 



The formula of rosaniline has been corroborated by the examination and analysis 

 of its salts, the most important of which are the following : 



Hydrochlorate. Prepared either by the action of hydrochloric acid, or of chloride 

 of ammonium, upon the free base, the monacid salt is deposited from its boiling 

 solution in well-defined rhombic plates, frequently in stellar forms. This chloride is 

 difficultly soluble in water, more soluble in alcohol, and insoluble in ether. 



The salt retains a little water at 100 C., but becomes anhydrous at 130 C. 



Like most of the rosanilino salts, this salt is very hygroscopic. The monacid 

 chloride dissolves more readily in moderately strong hydrochloric acid than in 

 water. If this solution, gently warmed, be mixed with very concentrated hydrochloric 

 acid, it solidifies on cooling into a network of beautiful brown-red needles, which have 

 to be washed with concentrated hydrochloric acid and dried in vacua over sulphuric 

 acid and lime, since water decomposes them with reproduction of the monacid com- 



