Some new bodies have been proposed to supersede chloroform, as a means of rendering a person insensible to pain during an operation. One of these is an organic compound called "amylene," a product of potato oil; another is oxyd of carbon. This is used externally on the diseased part; taken internally it is a poison, having ammonia as an antidote. The last is carbonic acid. The operation is performed under a stream of this gas, which produces insensibility in the part, and has been successfully used in the extraction of cancers, ulcers, and kindred diseases.