NAPHTHA, NATIVE 401 



the fifteen years of his experience as engineer of the Cleveland Gas-light and Coke 

 Company, in the manipulation of the gas varied results had been observed. In the 

 process of condensing and washing the gas, their usual method had been to condense 

 first and then to wash. At one time it was thought advisable to erect a spray- washer 

 between the hydraulic main and the condensers, as was the method in many gas 

 works. Soon after there was observed a rapid accumulation of naphthaline in tho 

 drain leading to the tar-well, in the purifiers and pipes about the works, and also in 

 the distributing mains in the streets. At a subsequent period these spray-washers 

 were removed and placed between the condensers and purifiers, used in connection 

 with the purifiers, and very much less naphthaline was crystallised. During the 

 periods mentioned the heats of the benches were what was termed ' high.' During 

 the past cold season there was used with the common bituminous coal from four to 

 eight per cent, of cannel coal. The heats were not high, the gas was kept hot while 

 passing from the retort-house to the condensers about 150 feet by encasing the 

 pipe ; the condensation was very gradual, by the use of an open-air condenser, and 

 but a small amount of water used in the scrubber and no spray-washer. During this 

 period they had no crystallised naphthaline. It had always been observed that wher- 

 ever high heats were carried more naphthaline was crystallised than with medium 

 heats ; and that when a bench was lightly charged, after being cleaned of carbon and 

 while hotter than usual, naphthaline appeared more abundantly than under ordinary 

 circumstances. His deductions from his experience at the Cleveland works were as 

 follow : The crystallising of naphthaline was caused first by ' high heats,' and the 

 amount increased by rapid cooling of the gas by contact with cold water, cold pipes, 

 and other rapid cooling ; and that naphthaline was more likely to be developed in 

 gas made from slack coal than from lump coal. The remedy he would suggest for 

 the annoyance was the use of a small percentage of cannel coal, in connection with the 

 common bituminous coals, moderate heats, long exposure of the gas to hot pipes or 

 ether condensing operations before reaching the cooling condenser ; slow cooling of 

 the gas, and scrubbing with a small amount of fresh or ammoniacal water of moderate 

 temperature ; and, also, when found necessary, the introduction of a small continuous 

 supply of naphtha into any horizontal pipes about the work after condensation, or 

 into the drips of the inlet and outlet pipes to the gas-holder. The evaporation of the 

 naphtha would dissolve the naphthaline crystals. 



Another gas-engineer remarked that high heats had been so constantly upbraided 

 as the parent of naphthaline, and so thoughtlessly and unjustly, that he must try to 

 rescue them from blame. He admitted that high heats undoubtedly place them in a 

 position to be annoyed with the crystal, but so did the use of steam put them in 

 jeopardy from railway accidents. Of late years they had been putting brain-work 

 into their retort-houses faster than into the other apparatus, and the result was the 

 unfortunate crystal under dissection. High heats, low seals, rapid evolution of the 

 gases, hasty removal from the retort, and sudden plunging at a high temperature into 

 the showers of spray- washers, or through yards of chilling condensers, soon gave birth 

 to the lusty and troublesome crystal nuisance that sheds its unthankful favours upon 

 gas managers. The agency of heats in producing naphthaline lies simply in convert- 

 ing into a gas, at a high heat, olefiant qualities, that at low heats pass over as oils. 

 In order to retain this (at that point) easily-condensed volatile oil in a gaseous form, 

 three methods were open to them : they might mix free hydrogen with their coal- 

 gas at a high temperature ; they might introduce into their coal-gas, gas made from 

 naphtha ; or adopt the plan of having a long connecting main, protected from atmo- 

 spheric changes, between the hydraulic main and condensing apparatus, so retaining 

 the crude gas as long as possible in contact with its own condensable vapours, and 

 subjecting it to a gradual lowering of temperature. He had made the practice of 

 introducing the water into his condensers at the ' outlet ' end, and taking the overflow 

 from the ' inlet ' end, so causing the gas to come first in contact with pipes somewhat 

 higher tempered than he could otherwise do, and so continuing his scheme of gradual 

 cooling. He used but little water in actual contact with the gas, believing more in 

 the efficacy of the dry scrubbing it got in passing the divisions of the washer than in 

 water as a cooling agent in that stage. Following these general views, he had suc- 

 ceeded in escaping any further trouble from naphthaline, save an occasional warning 

 nresence in his purifiers, when he accepted the hint and looked for something wrong 

 ut the back of them. When gentlemen came to understand the chemical laws govern 

 ing the deposit of naphthaline, the great step to its prevention would have been taken, 

 and it would pass out of the category of nuisances and be blessed for its useful 

 qualities. 



For the gas-engineer it seems most important to prevent the crystallisation of 

 naphthaline, and this it appears can be done by keeping the gas containing naph- 

 thaline ia contact with the light volatile oils ; though all the chemical properties of 



Vox,. lit DD 





