The smallest quantity of _laudanum_ which is known to have proved fatal to an adult is two drachms, from which death occurred within twelve hours. The exact quantity taken was, however, doubtful. Two grains and a half of the _extract_, a quantity said to be equal to four grains of crude opium, have produced a similar result. Much larger doses are, however, taken with impunity on many occasions, more especially by those habituated to the use of this drug, who remain almost unaffected by surprisingly large quantities. De Quincey, the English opium-eater, once found in a pirated edition of “Buchan’s Domestic Medicine,” a caution against taking more than “twenty-five _ounces_” of laudanum at one dose. He says that he always bore this _excellent_ advice in mind; and it does not appear that he ever took more than sixteen ounces of the tincture of opium as his daily allowance. In certain diseases, patients quite unaccustomed to the use of sedatives can take excessive amounts without narcotism being produced. In some cases of tetanus, for example, upwards of four ounces of laudanum have been given daily for a week, without any marked effect. On the other hand, it must not be forgotten that not a few individuals are unable to take even one-third of a grain without being narcotised. Young children are particularly susceptible of its effects; the tenth and twelfth parts of a grain having respectively proved fatal to infants two and five days old. Dr. Edward Smith has even recorded the case of an infant seven days old, who died comatose eighteen hours after having had administered to it about the twelfth of a grain of opium, or the quantity contained in one drop of laudanum.[C] The smallest fatal dose for a child on record is one of paregoric elixir equivalent to about one-_ninetieth_ of a grain of opium. On the other hand, they sometimes recover from very large doses indeed. The duration of a fatal case is generally from seven to twelve hours. The shortest period recorded is three-quarters of an hour; the longest, twenty-four hours. If the patient survives twelve hours there is good hope of recovery.