The black stone is used against poisoning of the blood caused by the bite of snakes, scorpions and other venomous insects. You have to bleed the site of the bite.
Place the stone on the bleeding spot and as soon as she is in contact with blood, it is attached to the place and coming off when it has absorbed all the poison.
After use they put it in hot water for half an hour, when the crackling stopped, they put in milk for 2 hours.
and finally washed in cold water and allowed to air dry and then it can be reused again.