COAL-TAR PRODUCTS. 293 



nine million tons of coal at 125. are worth but 5,400,000, 

 the waste products on this amount, after the gas has been 

 extracted, are, according to Dr. Siemens, actually worth 

 8,370,000.* 



The fact is that the coal-tar which the gas-makers were 

 so anxious to get rid of at any price, or no price, has 

 been discovered to contain many most valuable substances, 

 among which are the white crystalline acid called carbolic, 

 now universally used as a powerful disinfectant; naphthaline, 

 which crystallises in white pearly plates ; the colourless 

 liquid called benzole, and white waxy-looking paraffine. All 

 these are hydrocarbons, and as we have already seen that 

 the essential oils to which plants owe all their sweet scents, 

 are also compounds of carbon and hydrogen, it may not 

 surprise us to hear that the perfume of woodruff, melilot, 

 Tonquin bean, and many others, can be obtained from gas- 

 tar, which also yields the peculiar odour of jargonelle pears 

 used in flavouring cheap confectionery and oil of bitter 

 almonds. 



From benzole is obtained another colourless liquid 

 called aniline, which is now manufactured on a very large 

 scale, as, when mixed with other things, it produces the 



* 9,000,000 tons of coal at 125. .... ,5,400,000 

 Waste products on this amount : 



Colouring matter for dyes .... 3,350,000 



Sulphate of ammonia . . . . . 1,947,000 



Pitch ........ 365,000 



Creosote 208,000 



Carbolic Acid 100,000 



Gas-coke ....... 2,400,000 



,8,370,000 



