47:7 · The above entry sign structure turned 45 degrees for the alchemists during the seventeenth century meant keep, preserve. However, sometimes the alchemists used to mean burn out by making white-hot. This process means that the burned-out metal or compound gets rid of impurities while at the same time its essence is kept or preserved.
    According to Diderot it was used by eighteenth century chemists in France for zinc oxide or tutia, although the sign in this use often was drawn .
    In the so-called family system (see in Group 41:b) means child dies. Like below this entry sign is used in the French hobo or gypsy system for here there is nothing of any interest.
    During the eighteenth century natural scientists sometimes used this sign to signify the oxygen principle. The element oxygen was not discovered until the 1770s, although roughly half of the mass of this planet's surface layers of rock and soil consists of oxygen.