Is this the first time a rainbow was featured in an art exhibition?

July 1967.

Gustav Metzger is setting up his exhibition in the Filtration Laboratory at Swansea University. The lab was purpose built to investigate the flow of air and water, fitted with precision equipment to regulate pressure and direction. But Metzger's an artist, not a scientist, and saw only lines and possibilities, tools and tangents amongst the sterilised surfaces.

Six exhibits were installed on site. For the first, Metzger used plastic tubes and airpipes to engineer a dance of water and air - a vertical jet of air hitting and merging with a horizontal jet of water. "The space was very long, and as you came in, you were faced by a long row of windows with venetian blinds. The binds were down, it was winter, and I noticed that at noon the light would come in at a certain angle and when it went through the water jet you got this extraordinary rainbow effect on the walls...quite fascinating."

A light space filled with rainbows. Walk through to find a clear plastic cube - inside, the sun reflects off thousands of mica pieces spinning through jets of air. Past the cube, three pieces of polystyrene hover uncannily just above the floor - suspended by four streams of compressed air that pinned down the corners of the objects. At the farthest end of the room, a "small cubicle where liquid crystal was projected with a controlling system. The heating of the liquid crystal went on systemacially and for the first time I had a liquid crystal project which was ceaseless, hour afer hour." Metzger recalled; "it's beautiful to have this element of stability which at the same time you could see was totally explosive..I feel I achieved something in that this was literally off the ground."

Is this the first time a rainbow has been included in an art exhibition?