Sentence:  Even these explosives are, however, dangerous if the charges are large (above 300 grams for roburite and westphalite, and above 1000 grams for the <WSD>carbonites</WSD>), since then a momentary pressure on the air is developed (especially if the velocity of explosion is high) and a decided rise of temperature. 
Meaning of the word marked with <WSD> tags:  An explosive manufactured from a variety of materials, including nitroglycerine, wood meal and nitrates.