A feeder for finely divided solids from atmospheric pressure into a high pressure atmosphere. It has a chute to hold the solids at atmospheric pressure, and a valve with seals to deliver the solids into a loading chamber. There is an arrangement for pressurizing the loading chamber, and the chamber is oriented so that the solids will discharge through another valve by gravity flow into the high pressure atmosphere after pressurization of the chamber. There is also an arrangement for displacing the high pressure atmosphere from the chamber after discharge of the solids and before the next delivery of another charge from the chute.