58 



Messrs. A. W. Hofmann and A. Geyger on [Dec. 5, 



the chlorhydrate are confirmed by the investigation of the platinum salt. 

 This compound is obtained by precipitating a solution of the chlorhydrate 

 by excess of platinum perchloride ; dilute hydrochloric acid must be used 

 to wash this precipitate, as pure water appears to decompose it. The 

 platinum salt forms a yellowish-red crystalline powder, nearly insoluble in 

 water, alcohol, and ether. 



If the salt suspended in boiling water be treated with sulphhydric acid, 

 sulphide of platinum is slowly formed, whilst unaltered chlorhydrate of 

 safranine remains in solution. The analysis of the salt, dried at 100°, gave 

 numbers corresponding to the formula 



2(C 2l H 20 N 4 .HCl).PtCl 4 . 



Free base. — In order to prepare some other salts of safranine it was 

 necessary to obtain the free base. Remembering, when first we com- 

 menced the study of this new compound, the properties of the tinctorial 

 ammonias in general, we endeavoured to precipitate the base from the 

 chlorhydrate by alkalies. Ammonia, however, is without any action what- 

 ever on salts of safranine ; and only in the most concentrated solutions 

 does soda produce a precipitate which immediately redissolves on addition 

 of water. This precipitate is obviously nothing but chlorhydrate rendered 

 insoluble by the sodium chloride formed, or by the concentrated soda 

 solution. Free safranine being soluble in water, there remained no other 

 process for liberating the base than treatment of the chlorhydrate with 

 silver oxide. On evaporating the deep yellowish-red coloured liquid ob- 

 tained in this way, a deposit of red-brown crystals is formed on cooling, 

 which while moist scarcely differ from those of the chlorhydrate, but when 

 dried at 100° assume a greenish metallic lustre. Free safranine easily 

 dissolves in water and alcohol, but is insoluble in ether. Addition of 

 chlorhydric acid to the aqueous solution at once reproduces the crystal- 

 line chlorhydrate. We have not been fortunate enough to obtain free 

 safranine in a state of perfect purity ; the solution invariably retains a 

 small quantity of silver chloride, which separates with the crystallizing 

 product ; it may be recognized by burning the base, when a small incom- 

 bustible residue is left. If the chlorhydrate be reproduced from the free 

 base, so much silver chloride is mixed with the salt, that the percentage 

 of chlorine, found on analysis, is appreciably raised. An estimation of 

 chlorine in the chlorhydrate thus prepared gave 10' 8 per cent, instead 

 of 9*74. Free safranine, however, may be used without difficulty in the 

 preparation of other salts, the nitrate for instance. 



Safranine nitrate is easily obtained when an excess of dilute nitric acid 

 is added to a hot aqueous solution of the free base. On cooling the 

 salt crystallizes in red-brown needles, which are very insoluble in cold, 

 but readily dissolve in boiling water. They are considerably more soluble 

 in alcohol than in water. The nitrate is decidedly less soluble than the 

 chlorhydrate ; a solution from which the latter salt has been thrown down 

 by chlorhydric acid still gives a precipitate with nitric acid. 



