The quickness of the operation of nitrous oxide, will probably render it useful in cases of extreme debility produced by deficiency of common exciting powers. Perhaps it may be advantageously applied mingled with oxygene or common air, to the recovery of persons apparently dead from suffocation by drowning or hanging. The only diseases in which nitrous oxide has been hitherto employed, are those of deficient sensibility.—An account of its agency in paralytic affections, will be speedily published by Dr. Beddoes. As by its immediate operation the tone of the irritable fibre is increased, and as exhaustion rarely follows the violent muscular motions sometimes produced by it, it is not unreasonable to expect advantages from it in cases of simple muscular debility. The apparent general transiency of its operation in the pure form in single doses has been considered as offering arguments against its power of producing lasting changes in the constitution. It will, however, be easy to keep up excitement of different degrees of intensity for a great length of time, either by administering the unmingled gas in rapid successive doses, or by preserving a permanent atmosphere, containing different proportions of nitrous oxide and common air, by means of a breathing chamber.[231] That single doses nevertheless, are capable of producing permanent effects in some constitutions, is evident, as well from the hysterical cases as from some of the details—particularly that of Mr. M. M. Coates. [231] See R. IV. Div. I. page 478. As nitrous oxide in its extensive operation appears capable of destroying physical pain, it may probably be used with advantage during surgical operations in which no great effusion of blood takes place. From the strong inclination of those who have been pleasantly affected by the gas to respire it again, it is evident, that the pleasure produced, is not lost, but that it mingles with the mass of feelings, and becomes intellectual pleasure, or hope. The desire of some individuals acquainted with the pleasures of nitrous oxide for the gas has been often so strong as to induce them to breathe with eagerness, the air remaining in the bags after the respiration of others. As hydrocarbonate acts as a sedative,[232] and diminishes living action as rapidly as nitrous oxide increases it, on the common theory of excitability[233] it would follow, that by differently modifying the atmosphere by means of this gas and nitrous oxide, we should be in possession of a regular series of exciting and depressing[234] powers applicable to every deviation of the constitution from health: but the common theory of excitability is most probably founded on a false generalisation. The modifications of diseased action may be infinite and specific in different organs; and hence out of the power of agents operating on the whole of the system. [232] R. IV. Div. I. page 467. [233] That of Brown modified by his disciples.