COAL-TAR COLOURS 



ami cuke HI JUT. cent. From coal-tar may be prepared bonzene 

 (the ( ommercial benzol), naphthalene, anthracene and phenol, also pitcd. 

 nctly it may be said that benzene can be converted into aniliii". 

 alcnr iiitu iM.li'jotm (indigo), anthracene into alizarine, and phenol 

 ito rarltolir and. The reader will find numerous technical works thatdeal 

 tli these MiKstances and their manufacture. [Cf. Blount and Bloxam, 

 for Enyin. and Manuf., 1900, 55-87 ; Rawson, Gardner and Lay- 

 k. Diet. Dyes, Mordants, etc., 1901, 93-110.] 



Tin- coal-tar colours may be spoken of as discovered by Dr. (the late 

 r) \V. 11. IVrkin in 1856. He was then engaged in a study of the syn- 

 dic production of quinine, when he noticed that aniline on being oxidised 

 ive a colouring matter. This he produced separately and gave to the 

 l<> under the name of " Mauve." This was the first of the long series 

 colours destined in a remarkably short time to revolutionise the tine- 

 rial industries of the world the Aniline and Alizarine Colours. The 

 \ ue i ice of these modern mineral dyes has been more destructive to the 

 ictorial and textile industries of India than is commonly supposed. 

 ley have depraved the artistic feelings of the people, and demoralised 

 my of the indigenous crafts. But it doubtless can be upheld that the 

 mces of modern tinctorial science have, in their ultimate issues, been 

 reality more constructive than destructive. The majority of the Indian 

 ?etable dyes are fleeting, especially the yellows and greens. The best 

 lours are the reds and blues. All Indian dyes are relatively expensive 

 troublesome, and one of the most imminent modern dangers lies in 

 fact that there are good and bad, cheap and dear, fast and fleeting 

 ilities of the coal-tar dyes. It has been in fact computed that there 

 at present about 2,000 distinct colours of this kind offered for practical 

 the manufacturers of which are often prepared to send expert dyers 

 the workshops of their customers in order to instruct the operatives 

 the technicalities of the dyes they sell. Recently it has moreover been 

 H>osed that a Ci key-board " of colours should be established, with fixed 

 ibers for each shade, so that the buyers of Indian goods may be able 

 i dictate the colours to be used. This may be desirable for certain com- 

 rcial transactions, but with the art crafts it is likely to prove pernicious, 

 the famed natural dyes and tinctorial combinations of India have been 

 idy imitated and their vernacular names given to the fabricated 

 il-tar preparations (e.g. Peori dye, p.'765), so that nothing is left undone 

 it could expedite the complete overthrow of the indigenous crafts. This 

 itement is abundantly upheld by the returns of the imports. The 

 lilines and Alizarines received by India were in 1876-7 valued at 

 4,60,266 ; in 1886-7 they were Rs. 10,08,034 ; in 1896-7 Rs. 60,63,256 ; 

 1903-4 Rs. 82,67,010 ; in 1905-6 a slight decrease, namely to 

 75,71,314 ; and in 1906-7, Rs. 74,92,704. In another article (under 

 ligofera, p. 683) mention will be found of the progress in synthetical 

 duction of indigo. 



Coal : Coke. An inferior quality of coke is obtained as a by- 

 luct of the gas-works. It should not contain more than 10 per cent, 

 it is useful for burning cement and lime, or for domestic purposes, 

 len coal is carbonised in ovens for the express purpose of producing 

 coke, larger quantities are used than during gas-making. Coke is the 

 main product, not the by-product. The coke is therefore superior because 

 it has a higher calorific value. Caking coals are those best suited for 



345 



COAL 



Coal-tar 

 Products 



Demoralised 



Indigenous 



' 



Expensive. 



Indian Dyes 



imitated. 



Erpansiou 

 of Trade. 



Coke. 



Two Kinds. 

 Caking Goals. 



