The Birmingham age-herald., 1924-08-31
By c. B. BuTTERFIELD

oS Os Ds DO T AdAbE AA5A1O
 In 1922 there were eleven explosions In coal mines killing five or mere men each, making the total number of men killed for that year 260. In the year 1923 there were five explos- ions in coal mines involving the deaths of PA men and so far in 1924 there have been four very serious explosions. On January 25, 1924, B2 men were killed in an explosion in Illinois. On. January 26, 36 men were killed in an explosion in Pennsylvania. On March 8, an explosion in mine in Utah caused the death of 175 men and on March 25, an explosion in West Vir- ginia killed 25 men and completely wrecked the workings of that opera tion. The total number of deaths SO far for the year 1924, is 268.
 When mining men and the thousands of people not conversant with the sub ject read of these terrible catastrophes, they invariably ask the question
 Students of this subject unanimously agree that practically every mine ex- plosion could have been prevented.
 The surest way 10 prevent a mine explosion Is to exclude as far as prac- ticable all means of ignition or to con trol the use of mining apparatus so as to render them free from danger. Lights cannot be excluded, but they can be rendered safe. The same is true of explosives and electric apparatus which are required in other to produce coal at the lowest possible figure.
 Unfortunately, all of the potential means of ignition of the mine explosions cannot be entirely eliminated. There fore, a secondary line of defense for the prevention of an explosion must be adopted. that is, gas and coal dust must be made as difficult to ignite as possible.
 The ignition of gas can be prevented by the use of closed lights and, too, by properly loading, tamping and firing shots to prevent wind or blown out shots from, igniting the ges.
 This brings us to the most feared of all-"Coal Dust"
 Coal dust, when pure, fine and dry and raised into cloud in the presence of a source of heat, as for example, or an electric car, produces an ex- tion takes place between the carbon of
 
 Due to the explosibility of coal dust it should be treated in some way so that it will not explode.
 Many coal companies have for years been wetting down coal dust by water ing with a water car, automatic sprink- Ter or hose and nozzle. To a limited extent this means of placing coal dust in a non-explosive state has been sue cessful.
 It is, however, deceptive and often gives a false sense of security. If coal dust is to be kept in a safe and non- explosive state, it must be drenched al-i most daily, 50 that it has the consist ehcy of mud, and can be made into ball. If this system is resorted to, it requires continuous and constant sprinkling, due to the fact that. the air in the mine absorbs the moisture and this is especially true in the fall and winter when the air is dry. Many times when the mines are dry and water should be used, the coal com pany's reservoir is just about as dry as the mine. Finally the cost of effici- ent watering is very high.
 The fact that wetting coal dust so as to make 1t non-explosive is so costly and requires so much time and atten- tion has caused an investigation to be made to asceretain whether or not there is cheaper, and too, more efficient means of making coal dust non-explosive. The answer has been found in the application of rock dust to coal dust found in the entries and room necks.
 Mixture For Rock Dust
 Experiments by the United States Bureau of Mines have proved the best rock to be used in rock dusting coal mines in order to prevent an explosion of coal dust is pure limestone, dolo- mite, gypsum and anbydrite. The ad- vantage of pure limestone over other kinds of rock is that limestone dust is light in color. This serves to per- init ready observation of freshly dis tributed coal dust, and to increase the illumination of the entries. It is also conceded that in some mines, after the entries have been rock dusted several times, the rock dust will, to some ex- tent, keep the air from the roof, which should cause us to have a better roof in some mines. When entries have been rock dusted with lime stone dust. the illumination will be increased to very great extent and this will as- slst materially in reducing accidents.
 The finer the size of particles of rock dust, the more easily it is raised in. the air with coal dust, so, it is to the advantage of those interested in the prevention of coal mine explosions to use very finely pulverized rock dust