There are two main types of fire extinguishers: stored-pressure and cartridge-operated. In stored pressure units, the expellant is stored in the same chamber as the firefighting agent itself. Depending on the agent used, different propellants are used. With dry chemical extinguishers, nitrogen is typically used; water and foam extinguishers typically use air.
The Encyclopedia Britannica, which has been in continuous print since it was first published in Edinburgh in 1768, said today that it will continue with digital versions currently available online. The final set of the 32-volume printed edition remains available for sale on the company's website for Â£890 ($1,400). Scroll down for video
On 1616, John Bullokar contributed on the history of dictionary with his English Expositor. Elisha Coles published his English Dictionary in 1676. Glossographia by Thomas Blount on 1656, contains more than 10,000 words along with their etymologies or histories.