domestic works at home. During the putrefactive
fermentation of the woad ammonia is formed and
hydrogen evolved. The latter, while in the nascent
state, reduces the blue indigo to the state of white
indigo, which, being soluble, can penetrate the wool
to be dyed, where it is deposited in the insoluble
state as blue indigo, on exposure to the oxygen of
the air.
There is an incident in the life of S. Piran, or Kieran, who founded a church, S. Keverne, in the Lizard district, which is connected with dyeing with woad.
His mother was one day engaged in preparing the dye, called by the Irish glasin. Kieran, then a child, was present; and as it was deemed unlucky for a male person to witness the preparation of the dye, she bundled him out of the cabin, whereon he uttered a curse, " May there be a dark stripe in the wool," and the cloth in dyeing actually did exhibit a dark grey stripe in it. The glasin was again prepared, and again Kieran was turned out of the house, whereon he again cursed the process that the material to be dyed might be whiter than bone, and again it was as he had said. The woad was prepared a third time, and Kieran's mother asked him not to spoil it, but, on the contrary, to bless it. This he did with such effect that there was not made before or after a glasin that was its equal, for what remained in the vat served not only to colour all the cloth of the tribe, but made the cats and dogs that touched it blue as well. The explanation of the miracle is very simple. The two failures were due to imperfect fermentation
