Chopsticks, a pair of small even-length tapered sticks, are the traditional eating utensils of East Asia (China, Japan, Korea, and Vietnam, the four "chopstick cuisines") as well as Thailand, where they are now restricted just to soup and noodles since the introduction of Western utensils by King Rama V in the 19th century. Chopsticks are commonly made of wood, bamboo, metal, bone, ivory, and in modern times, plastic as well. It is believed that silver chopsticks were used in the Chinese imperial palace to detect poison (possibly metallic oxides) in the Emperor's meals; if poison was present, the chopsticks would become blackened owing to displacement reactions on the silver.