For some odd reason that suddenly reminded me of Reckitts blue bags from my childhood, I see they are still available on Amazon thought they had died out years ago lol
I had to google Reckitt's since it was strictly Bristish. I learn something new everyday here. I hit "Post" before I had a chance to say that it's a bluing agent for whitening clothes before chemicals were made. The company made all sorts of laundry products.