APRir.. 1911. 



KNOWLEDGE. 



129 



must consider not onl\' the uaste of useful carbon 

 and so of heat — that is bad enough, especially in its 

 indirect results — but we have to consider the loss of 

 those extremely valuable bye-products that might be 

 obtained if the same fuel were heated in retorts and 

 made to yield up its gas. The wealth of England 

 is partlv due to its splendid coal-fields. Coal being 

 part of the national wealth, it should be the aim of 

 all good citizens to prevent the waste of it. But as 

 things are we allow a large part of our wealth to 

 escape up the chimney. This is bad science and 

 worse political economy ; it means we are spending 

 capital as well as income : but unless the women will 

 approach the subject in a different spirit there is not 

 much prospect of reform. 



To make the matter clear, it will be necessar\' to 

 explain very briefly what happens in the manufacture 

 of coal-gas. Coal is heated in closed vessels called 

 retorts and the gases driven off led awa\- into 

 gasometers, and thence to the mains that supply our 

 houses. Now the three chief residual products of 

 this process are : coke, an ammoniacal liquor, and 

 coal-tar. The coke is principally used in manu- 

 factures : its value depends on the kind of coal from 

 which it is got : some kinds yield a coke of great 

 value commerciallv, the gas companies deriving a 

 large income from its sale. To some slight extent it 

 is used in domestic grates, especialK" in kitchen 

 ranges. But the second product. amiu(.)niacal liquor, 

 is still more important. .\ ton of cannel coal will 

 }-ield eighteen to twenty pounds of ammonia un the 

 form of sulphate), ordinar\- coal \-ields about sixteen 

 pounds. The chief use of the sulphate of ammonia 

 is as a fertiliser of soils, and for this purjiosc it 

 realizes good prices. The third b\e-product is tar 

 liquor. This substance yields, by distillation, a wide 

 range of products of great and increasing industrial 

 value. In the process some highh- volatile pro- 

 ducts are given off — consisting principalh- of benzol 

 and afterwards a large amount of light nil called 

 " naphtha " (a mixture of h\-dro-carbons). .\t this 

 point the residue in the retort is callei.1 " arti- 

 ficial asphalte," and as such has a commercial 

 value. But if the heat is forced and distilla- 

 tion continued a large amount of hea\y oil is 

 obtained, and the mass left in the still is hard pitch. 

 The heav\- oils are a mixture of naphthalin. phenol 

 (carbolic acid), cresol (cresylic acid), and anthracene 

 and so on. The benzol obtained in the first stage of 

 distillation is the basis of aniline and its warious d\es. 

 Naphtha is used as a sohent and in other wa\'s. 

 Carbolic acid is largely used as a disinfectant and 

 also is the basis of many valuable dyes. Anthracene 

 is the basis of a very valuable dye called " artificial 

 alizarin "" and most of the abo\e substances have 

 other applications of minor importance. The 

 following figures, kindly supplied by the secretar\- 

 of the Gas Light and Coke Company, mav be quoted 

 here. For the year ending June 30th, 1910. this 

 company purchased coal to the \alue of £1.052.000. 

 The revenue from coke was £"536,000. Sulphate of 

 ammonia and cyanogen products vielded £1X4.000. 



From the latter are obtained sodium cvanide, largely- 

 used in gold mining, Prussian h\jz, and so on, used 

 for other chemical processes. Ti.i ether bye-products 

 e.g., tar, pitch, creosote, benzol :.nd anthracene 

 brought in a revenue of £"95,000. I': v.jll thus be 

 seen that the total revenue from bye-products 

 amounted to the large sum of £"815,000; i.e., over 

 three-quarters of the value of the coal usovi. 



The abo\e \er\- brief account suffices to prove that 

 several inqiortant industries depend upon gas-making. 

 Consequently the more gas is used for " domestic " 

 heating, cooking and lighting, as well as providing 

 motive-power by working gas engines, the more men 

 and women will find employment in these industries, 

 thus at the same time earning a li\ing h)r themselves, 

 and increasing the natural wealth of the country. 



In the last ten years or more, enormous improve- 

 ments have been made in the domestic fire grate : it is 

 now not only more artistic, but much more effective 

 ami economical, and thus a further step has been 

 gained in diminishing smoke production in large 

 towns. Many attempts have been made to construct 

 a smokeless domestic grate, but this is almost 

 impossible ; for when once the hea\'\- carbonaceous 

 smoke has been produced, it is ver\' difficult to burn 

 away the carbon particles completely, on account of 

 the large volume of nitrogen present with the oxs'gen 

 in the air passing up the chimney. Sn that the 

 best method ot preventing smoke is to jiiit on the 

 coal in \er\' small (]uantitii-'S. Another good [)lan is 

 to liurn wood or coke with the coal. The use of 

 anthracite coal would result in a smokeless and very 

 hot combustion, but it is difficult to light and also 

 requires a special stove. Consequently the initial 

 cost largeh- stands in the way of the general use of 

 anthracite for domestic use, and also it is obvious 

 that any great demand for such coal would create so 

 great a rise in prices as to render its use prohibitive, 

 the suppl\- being limited. The use of half-baked 

 coal is not a new idea, but since " Coalite "" was put 

 on the market attention has once more been turned 

 to this method. The "Coalite"' process has one 

 ad\-antage, viz.. that tlie fuel is of greater unifortuitw 

 and the A'ield of tar is doubled, instead of being 

 decreased. In the opinion of a leading chemist, 

 " Coalite "" will be the ideal fuel for home use, but to 

 the present writer it seems that the onh' satisfactory 

 solution of the problem lies in the abolition of coal- 

 fires, their place to be taken chiell\' by gas-fires and 

 gas-stoves. This is. undoubtedly, the proper scientific 

 w'a\' of solving the smoke problem, and of preventing 

 the waste of precious coal. Not that it is the only 

 solution, for in larger houses, hotels, public buildings, 

 colleges, and such places, hot water heating is almost 

 a necessity. The furnace in those cases might be 

 constructed to use gas instead of coal. Electric 

 radiators might with ad\'antage be used in small 

 rooms, and for warming odd corners. At present, 

 however, they are expensive. For some years past, 

 as all Londoners thankfulh- recognise, London fogs 

 ha\'e been much fewer and tar less dense than was 

 formerly the case, and it is generally recognised that 



