After the removal of antimony, arsenic and tin, the softened lead may still contain silver and gold, and sometimes bismuth. The removal of the precious metals by the Parkes process is based on the fact that they are more soluble in zinc than in lead. In this process, the lead is melted and mixed with zinc at 480 °C. The temperature of the melt is gradually lowered to below °C, at which point the zinc (now containing nearly all the silver and gold) begins to solidify as a crust on the surface of the lead and can be skimmed off. An alternative procedure, the Port Pirie process, used at the Port Pirie refinery in Australia, is based on similar metallurgical principles ( Lead Development Association International, 2003c ).
After the double-murder suicide, former wrestler Christopher Nowinski contacted Benoit's father, suggesting that years of trauma to his son's brain may have led to his actions. Tests were conducted on Benoit's brain by Julian Bailes, the head of neurosurgery at West Virginia University, and results showed that "Benoit's brain was so severely damaged it resembled the brain of an 85-year-old Alzheimer's patient." He was reported to have had an advanced form of dementia, similar to the brains of four retired NFL players who had suffered multiple concussions, sank into depression, and harmed themselves or others. Bailes and his colleagues concluded that repeated concussions can lead to dementia, which can contribute to severe behavioral problems.