Vandals threw acid on two priceless works by Rembrandt in a gallery in Kassel yesterday in the lateset in a series of attacks on paintings in West Germany.

One of the damaged paintings, "Jacob Blessing the Children of Joseph," was described by art expert's in Washington as one of Rembrandt's masterpieces. The other Rembrandt was a self portrait.

A spokesman at the Wilhelmshoehe Palace in Kassel said the two Rembrandts and two other Dutch paintings were "badly damaged." Associated Press quoted witnesses as saying the face of the Rembrandt self portrait was completely erased.

The other two damaged paintings were "The Architect" by Nicholas Maes and "Christ Appears to the Magdalena" by Willem Drost. Both were students of Rembrandt.

Art experts in Washington said there was no way to place a monetary value on the paintings by Rembrandt, one of the greatest artists in history. Arthur Wheelock, curator of Dutch and Flemish painting at the National Gallery, said "Jacob Blessing the Children of Joseph," painted in 1656, is from the same period as a painting sold to the Metropolitan Museum of Art in New York for $2.3 million.

The painting in Kassel, he said, is "much larger" than the Metropolitan Museum's 1961 acquisition. "Aristotle Contemplating a Bust of Homer." Wheelock described "Jacob" as one of Rembrandt's "most moving paintings."

Museum officials said "Jacob" was the least damaged of the four, but did not say whether it could be restored.

Police said visitors to the gallery reported seeing two suspicious looking men near the damaged paintings just before the vandalism was discovered.

One of the two, described as about 45 years old and wearing a facial bandage, resembled a suspect in an attack Aug. 24 in the Duesseldorf city museum. In the attack, a painting of Archduke Albrecht by the Flemish master Peter Paul Rubens was destroyed.

Before yesterday's attack there were 10 similar attacks on paintings this year, the West German news magazine Der Spiegel reported. The vandalism has prompted many West German museums to protect their works in glass cases or to search visitors.

The Duesseldorf museum has been closed until security devices can be installed.

Der Spiegel said West German authorities had theorized that the art vandal had a complex about being looked at because almost all the paintings attacked were portraits whose subjects looked straight at the viewer. The portraits were always hit in the area of the eyes, the magazine said.

Wheelock, who during a recent visit to West Germany saw some of the art that was attacked said restorers were optimistic that the damage could be repaired. He cautioned that none have been restored, so far, however, and said that they will "never be the same."

"Jacob Blessing the children of Joseph" shows the elderly Jewish patriarch at the moment he blesses his younger grandson, while his son, Joseph, tries to move his hand to the head of the elder grandson.

Wheelock said the painting "has such a marvelous warmth, . . . it is very tender . . . with the subtle play of the hands. Its calmness and quiet overwhelm you."