Liquid supplying device having tank and cartridge attachable thereto

An image forming apparatus comprising:

• a liquid supplying device comprising:
• a tank, and
• a cartridge configured to be attached to the tank in a horizontal direction, the cartridge comprising a first storage chamber configured to store liquid;
• and
• a recording portion configured to eject the liquid supplied from the tank;
• the tank comprising:
• a second storage chamber configured to store the liquid;
• a liquid passage in communication with the second storage chamber, the liquid passage having a first end connected to the second storage chamber and formed with a first opening, a second end opposite to the first end and formed with a second opening open to an atmosphere, and a first horizontal portion extending from the second opening in the horizontal direction;
• a gas passage in communication with the second storage chamber, the gas passage having a third end connected to the second storage chamber and formed with a third opening, a fourth end opposite to the third end and formed with a fourth opening open to the atmosphere, and a second horizontal portion extending from the fourth opening in the horizontal direction;
• and
• an air communication portion having an air communication opening allowing the second storage chamber to communicate with the atmosphere;
• wherein, in an attachment state where the cartridge is attached to the tank, the first storage chamber is connected with the second storage chamber via the liquid passage and the gas passage, the first storage chamber is in communication with both the second opening and the fourth opening, the first storage chamber has a portion positioned above the liquid passage and the gas passage, and the second storage chamber is positioned below the first horizontal portion of the liquid passage and the second horizontal portion of the gas passage such that the liquid level of the second storage chamber is kept below the first horizontal portion of the liquid passage even when the liquid level of the first storage chamber is above the first horizontal portion of the liquid passage.