At 3 o'clock we headed for the Tendercare Hospice to visit my Uncle Verner, the last living member of that generation from either side of my family. To paraphrase Dr. Suess from "You're Only Old Once", he was in pretty good shape for the shape he was in. He was much more lucid than we had been led to believe he might be. We talked for about 20 minutes and looked at pictures of his new great grand-daughter. Then we headed out on the 2 hr+ drive home.
My Uncle Verner worked until retirement at Dow Chemical in Ludington. One of the processes there was a giant rotary kiln that cooked dolomite (CaMg(CO3)2) into mixed calcium and magnesium oxides. Using careful pH adjustments the calcium and magnesium compounds were separated. My Uncle performed the test to make sure the process was properly completed. The test is the titration for magnesium in the presence of calcium using EDTA. EDTA, or ethlyene diamine tetra acetic acid, is known as a chelating compound and loves to grab ions of things like magnesium and calcium in solution. Think of EDTA as a man with a pair of hands at every joint and magnesium and calcium as women, with magnesium being slightly better looking. During the titration the EDTA grabs the magnesium first. You can tell when the magnesium is used up when the indicator dye changes from blue to purple. -My uncle and I have Daltonism.
John Dalton, an early chemist, found other chemists disagreed with him on his color descriptions of various compounds he made. He first documented red-green color blindness or Daltonism.
That blue to purple change can be very subtle because the difference is just red. Unless you use North Light. Light from a North facing window just has the blue light from the sky without the full spectrum of direct sunlight or the redness of artificial light. With North light the titration goes from blue to dark, -an easy end point to see.
When I did the same titration in college chemistry I got an "A" in that particular lab.
He is my last living relative who sees the world the way I do.