Phosphorus is an essential element for life. Forms of it are found in DNA, RNA, and all living cell membranes. It is the sixth most abundant element in any living organism. Phosphorus can also be highly poisonous and combustible (white phosphorus is used in many destructive weapons, such as napalm). It was also the first element discovered since ancient times. The person who made this discovery was Hennig Brand in 1669, who did so while he was playing around with large amounts of human urine.