NEW EXPLOSIVE

New Zealand Herald, Volume LXXIII, Issue 22318, 16 January 1936, Page 10

NEW EXPLOSIVE

USE IN THE DOMINION modified TYPE APPROVED THAWING DANGERS REMOVED STATEMENT BY MINISTER [by telegraph—own correspondent] WELLINGTON, Wednesday In the interests of public safety, the Government has decided that a modified non-freezing type of explosive, employed in mining and for other similar purposes, will in future be supplied for the New Zealand market. With that end in view negotiations were recently concluded with Nobels (Australasia) Proprietary, Limited, which supplies practically all the explosives used in New Zealand. . The Minister of Internal Affairs, Hon. W. E. Parry, stated to-day that the decision had been reached as a result of rigid tests by Government experts. The position now would be that the lead given by Great Britain would be followed, and that in future only "polar", types of explosives would be approved for importation into New Zealand, except for special purposes. The Minister explained that ono of the physical properties of nitroglycerine, which is the basis of most of the "high" explosives, such as gelignite and blasting gelatine, . was that this material froze at a temperature of 40deg. Fahrenheit, or Bdeg. above the freezing point of water. In its frozen condition the explosive was very irregular in its action, being sometimes extremely insensitive and failing to explode in boreholes and on other occasions capable of being detonated by a comparatively minor shock. Departmental records showed that the number of accidents occurring in the use of explosives was always higher during the winter than in th*» summer months. It was probable that the majority of the accidents were due to the explosive used being either frozen or in a "chilled" condition, in which it was less sensitive than normally to explosion by a detonator. The standard practice recommended by the makers when explosives were found _to be frozen was to thaw them in a jacketed pan of hot water. However, in spite of continual warnings, miners and others often adopted unsafe methods of thawing, which resulted in accident. One such instance occurred at Halcombe last July, when a house was wrecked and all the occupants were injured, owing to the placing of frozen explosives in a kitchen oven to thaw. Mr. Parry said that as an old miner he realised to the full the value of the advance which had been made in the production of a non-freezing explosive and he had little doubt that the use of the improved type of explosive would result in much greater freedom from accident in the future.