220 James "W. Helps on some 



On further treatment these products yielded — 



90 per cent, benzol 6 gals. 



Solvent naphtha 74- 



Carbolic acid 6J 



30 per cent, anthracene 0-50 cwt. 

 Equal to pure anthracene "15 ,, 



Having obtained the first-named prodvicts, further treatment is 

 necessary before they are of much practical use ; the light oils 

 are therefore rectified for the production of naphthas of vai'ying 

 qualities. To obtain from these the benzol, toluene, &c., a very 

 careful system of rectification is necessary. 



We have now obtained the Benzol which is the compound used 

 for the preparation of aniline ; it is a colourless liquid with a 

 peculiar smell, its formula is CgHg sp. gr. at 0- C = 0-8991, 

 boiling at 80° C. It is, of course, only possible for me to touch 

 upon one or two of the various bodies which can be obtained 

 from it; I will therefore proceed to explain the treatment 

 adopted for the production of aniline. 



To begin with, the benzol is treated with nitric acid, or a 

 mixture of that acid with sulphuric acid ; by this means one 

 atom of the hydrogen in benzene is replaced by one of nitric 

 peroxide, for the formation of Nitro-be7izetie, the properties of 

 which I have already mentioned ; this liquid is then washed with 

 lime and water for conversion into aniline ; it is generally 

 subjected to a treatment discovered by M. Bichamp, which con- 

 sists in reducing it by means of ferrous acetate. 



It was, as I have said, from this aniline that Perkin made his 

 purple dye ; his success, of course, set others to work, and before 

 long M. Veguin, by boiling aniline with tetrachloride of tin, pro- 

 duced a splendid crimson, known as Magenta ; many other ways 

 of making it were discovered, but that of Mr. Medlock was the 

 great commercial success ; it consisted in treating the aniline 

 with arsenic acid, and resulted in a large fortune being made. 



Let me quote Mr. Leicester Greville as to the tinctorial 

 powers of this dye : — 



"100 lbs. of coal = 5 lbs. of tar — 2 ozs. of benzene = 

 1040 grains or 2^ ozs. of aniline = 207 grains of magenta. 

 This quantity is sufficient to dye 8 lbs. of wool, or to print 

 207 yds. of calico : in other words, 1 grain of magenta will print 

 1 yd. of calico 1 per cent, in weight." 



From magenta many beautiful dyes are obtained, such as 

 Nicholson's blue, which I have here ; it is an alkaline blue, and 

 a fabric dyed in it is almost colourless, until dipped in a weak 

 acid solution ; it will not rub off. 



Magenta treated with iodide of methyl gives a lovely green, 



