| # Class 4 | Flammable Solids or Substances |
|---|---|
| 4.1 | Flammable solids Ex : Nitrocellulose, Magnesium |
| 4.2 | Substances liable to spontaneous combustion Ex : Aluminum Alkyls, White Phosphorus |
| 4.3 | Substances which in contact with water emit flammable gases. Ex : Sodium, Calcium, Potassium |