The glass balls or amulets possessed by the druids, either for mysteries or for ornament, were known as ‘adder stones’ in several Celtic languages: Bret. glain neidr, ScG gloine nathair, W glain nadredd; but in Cornish it is millpreve. The stones were thought to have been formed during the summer by bubbles, blown from the mouth of the adder and hardened by sliding down the length of its back, forming a crystal ring, worn as an amulet. The adder is the only poisonous snake in the British Isles.
Adder stones are also called Serpents' Eggs and Snake Eggs. They were held in high esteem by the Druids. According to them the peculiar virtue resident in the stones was that they secured success in law-suits, and free access to kings and rulers. Many adder stones are still preserved as charms in those rural areas of Britain where the Celtic population still lingers. In some parts of Wales the stones go by the name of Gleini na Droedh and Glaine nan Druidhe (the Magician's or Druid's glass). The legend behind the properties of the stones is that they were believed to have been made by serpents. The snakes, it was said, gathered together in a wriggling, slimy mass to generate the stones from their slaver, and shoot them into the air from their hissing jaws. It is a curious omission in superstition that such stones, thus made, were never associated with the curing of a serpent's bite. The gathering time of the snakes was held, in Cornwall, to be on Midsummer Eve; in Wales, on the eve of May Day. So recently as the early 1900s the authors were told, in all seriousness, by people in the Principality that they had witnessed such a congress of snakes, and had seen the magic stones in the midst of froth. The stones are of various colours-- green, pink, red, blue and brown. There are a number still preserved in several museums in the country; and many of these are perforated. It was held that the perforation was caused, after the stone had been conflated by the serpents generally, by one of the serpents sticking its tail through the still viscous glass. The test of the genuineness of an Adder Stone was to throw it into a moving stream; if genuine it floated against the current, and no weight attached to it could make the stone sink.
The glass balls or amulets possessed by the druids, either for mysteries or for ornament, were known as ‘adder stones’ in several Celtic languages: Bret. glain neidr, ScG gloine nathair, W glain nadredd; but in Cornish it is millpreve. The stones were thought to have been formed during the summer by bubbles, blown from the mouth of the adder and hardened by sliding down the length of its back, forming a crystal ring, worn as an amulet. The adder is the only poisonous snake in the 