herald (plural heralds) 1  A messenger, especially one bringing important news. 2  A harbinger, giving signs of things to come. ( 3 heraldry) An official whose speciality is heraldry, especially one between the ranks of pursuivant and king-of-arms. ( entomology) A moth of the species Scoliopteryx libatrix.
a fire nozzle weighs approximately  ten to fifteen pounds.
However, the mass of oxygen and nitrogen are different, and so the mass percent of oxygen is not 1/3. Nitrogen atoms weigh 14 grams/mole, and oxygen atoms weigh 16 grams per mole, so N2O weighs 44 grams per mole, so the percent oxygen is: 16 Ã· 44 *100% = 36.36% by mass.