First, the extinguisher valve is removed and the threads and interior of the cylinder are checked for corrosion, pitting, and any other abnormalities. [29 CFR 1910.157(f)(3)] If the cylinder passes the visual inspection, it is placed into a steel chamber, which is then filled with water at normal pressure.
Updated April 17, 2017. The earliest dated printed book known is the Diamond Sutra, printed in China in 868 CE. However, it is suspected that book printing may have occurred long before this date. In 1041, movable clay type was first invented in China.
George Allen & Unwin Ltd. of London published the first edition of The Hobbit on 21 September 1937 with a print run of 1,500 copies, which sold out by December because of enthusiastic reviews. This first printing was illustrated in black and white by Tolkien, who designed the dust jacket as well.