EXPLOSION IN MINES.

New Zealand Herald, Volume LI, Issue 15711, 11 September 1914, Page 7

EXPLOSION IN MINES.

RESULT OF EXPERIMENTS.

DISTINGUISHED SCIENTIST

Anyone in Lower Symonds Street last evening, and thinking about the war, might have been pardoned it' he had imagined the presence of a Maxim gun in the vicinity. But there was no danger • the series of short, sharp explosions came from the Choral Hall, where Professor H. B. Dixon, M.A., Ph.D., F.R.S., the occupier of the chair of chemistry at the University of Manchester, was delivering a fascinating lecture upon " Explosions." Professor Dixon recently attended, in Australia, the conference of the British Association for the advancement of science, | and a part of the noteworthy address, and some of the demonstrations which he gave there, were repeated last night in his lecture, which was delivered under the auspices of the Auckland Institute. Professor H. W. Segar was chairman.

There were designed and undesigned ex - plosions, said the. lecturer, and he had devoted many years to the study of undesigned explosions, particularly those which occurred in coal mines. By means of simple explosions, in which he used oxygen and hydrogen, coal gas, gun-cotton, cordite, picric acid, etc., the lecturer demonstrated the nature of this chemical reaction, and how gaseous explosions might be divided into three phases—slow propagation by conduction, the vibratoring period, and the rapid detonation or explosion wave. By photographing explosionsa delicate process carried out by having a long film on a rapidly spinning-wheel inside the camera— had traced the three phases, and had given particular attention to the explosion wave, and had applied the Knowledge thus gained to his work in con- [ nection with coal mines. It had been [ found that if there was a wall close to the beginning of an explosion, | the explosion in that place would ! show much greater violence than if it had been in an open space and that thus an explosion getting a "kick-off' was more rapid and violent; that if an explosion ran some distance, as down a gallery, it gained greater violence the farther it went; and that, under some conditions, it would travel 3000 yds in a second.

Then the lecturer described the experiments on explosions in mines, which are being Carried out on a large scale by a committee of the Home Office in Cumberland ; and demonstrations were carried out to show that if a fine, inert (non-inflam-mable) dust were generously scattered in a place where there was an explosive mixture the danger of an explosion would be Tendered almost non-existent. Mines in England had already been treated in this way, with very satisfactory results. It was necessary, however, to 6tudy the nature of the inert dusts because some were very harmful to breathe.

Although necessarily of a highly technical nature, the experiments and some excellent photographs allowed the large audience to follow the lecture easily and intelligently, and at its conclusion the vote of thanks, moved by Mr. J. H. Upton, was very be .rtily tarried by acclamation.