SCIEXCE-GOSSIP. 



EXPLOSIONS IN ELECTRIC-LIGHT MAINS. 

 By J. Alfred Wanklyn axd W. J. Cooper. 



A N essential feature of almost every- great 

 ■^ advance in those arts and manufactures 

 which accompany, and in a sense form constituent 

 parts of, civilisation is peculiar and unlooked-for 

 dangers attendant on each great advance. The 

 steam-engine had its own peculiar dangers, as, for 

 instance, the liability of the steam boilers to burst. 

 The fear that the gas-holder would be prone to 

 explode, which in the early days of gas-lighting 

 was very generally felt, belongs to the imaginary 

 order. Other dangers there have been which were 

 real enough but quite unlooked for. There was the 

 mysterious explosion in the gas-mains in France, 

 which was traced to a most interesting source. It 

 appeared on making investigation that copper 

 service-pipes had been put down in some localities 

 in France, and that that interesting hydro-carbon, 

 Acetylene, which is one of the constituents of coal- 

 gas, had somehow formed its well-known compound 

 with the copper. That compound bears the name 

 ' ' acetylide of copper, ' ' and is endowed with explosive 

 properties ; and the mysterious French explosion 

 was attributed to acetylide of copper. 



Just as there have been mysterious gas explosions 

 in the past, so now we have mysterious explosions 

 connected with the installation of the electric light. 

 Some of these recent mysterious electrical 

 explosions which have taken place in London, 

 promise even greater interest than the French 

 acetylene explosions in the gas industry. They 

 carry the mind back to that great achievement of 

 a now well-nigh forgotten English chemist, in the 

 year 1807. At that date {now in ancient chemical 

 history), the great English chemist, Sir Humphrey- 

 Davy, discovered potassium, which he obtained by 

 electrical decomposition of caustic potash. The 

 alkali-metal, scdium, which is twin -sister to 

 potassium, was likewise, in that same year, 

 discovered by Davy. The conditions for the 

 electrical separation of the metal sodium from 

 its compounds, which Davy realized with great 

 labour, care and forethought in the year 1807, 

 appear to have realized themselves spontaneously 

 in a most wonderful manner in these latter days in 

 London. Among the current news of the day, a 

 short time ago we read that metallic sodium was 

 found coating the wires conveying the electric 

 current. Sodium decomposes water when brought 

 into contact with it, and decomposes it with 

 violence and explosion. The explosions to which 

 we refer have taken place in the Euston Road and 

 its neighbourhood within the last two years. The 

 cause of the explosions was at first supposed to be 

 the accumulation of an explosive mixture of air or 



coal-gas in the vicinity of the service-mains. But, 

 as we have said, closer investigation brought to 

 light the fact that in some instances there was an 

 actual deposit of metallic sodium, and that deposit, 

 when exposed to the action of water, is quite 

 adequate to produce explosions, and to kindle 

 explosive gaseous mixtures. 



The explosions in the Euston Road were fortu- 

 nately not attended with any fatal result, and the 

 damage to property was very trifling. The circum- 

 stance that they happened during a political 

 dynamite scare attracted rather more attention 

 to them than in ordinary times. 



Early on a Sunday morning in the beginning 

 of 1894, one of us, being on a visit to Endsleigh 

 Gardens, was startled from sleep by a loud explosion 

 which was at once set down to the dynamiting 

 fraternity. During the next few months there were 

 several explosions of a very similar kind, and an 

 official enquiry was ordered, and finally Major 

 Cardew, investigating on the part of the Govern- 

 ment, reported upon two explosions later on in the 

 same year. The official report makes no mention of 

 dynamiters but attributes the explosions to the firing 

 of explosive mixtures of coal-gas by the electric 

 spark, or by the flame arising from the contact of 

 metallic sodium and water. Here we would remark 

 that granted the presence of metallic sodium and 

 moisture, that state of things is quite adequate 

 to the production of the Euston Road explosion, 

 and that the existence of the mixture of air and 

 coal-gas need not be assumed at all. The sodium 

 explosions which have taken place in the manu- 

 facture of pure caustic soda from metallic sodium, 

 and which have indeed caused one manufacturer 

 to abandon that operation on a large scale, testify 

 abundantly to the adequacy of sodium and moisture 

 to occasion such explosions. 



It goes without saying that if you are to obtain 

 metallic sodium as a coating to the wires conveying 

 the electric current you must first permit some 

 compound containing sodium to come into relation 

 with those wires; and Major Cardew very- per- 

 tinently warns against suffering the formation of 

 an incrustation of common salt, the prime source 

 of sodium. 



One of the most satisfactory aspects of the 

 subject is the circumstance that such explosions as 

 we are considering are absolutely preventable. 

 That there can be such explosions under certain 

 conditions needs but to be pointed out in order 

 that the proper steps may be taken to ensure that 

 the conditions shall never again be realized. 



Nob Maiden, Surrey ; May 14th, 1895. 



