In the course of experiments on nitrous acid, detailed in [Research I]. made in September, October, and December, 1799, I several times experienced a severe oppression on the chest and difficulty of respiration, not unanalogous to that produced by oxygene, but much more violent, from breathing an atmosphere loaded with nitrous acid vapour. This fact seemed to confirm Mr. Watt’s suspicion. I confess, however, that I have never been able to detect any smell of nitrous acid, either by means of my own organs or those of others, during the production of oxygene; when the gas is suffered to pass into the atmosphere. The oxygene breathed in the experiments detailed in the text, had been for some days in contact with water.
[215] In the same manner as the debility from intoxication by two bottles of wine is increased by a third.
[216] I ought to observe that my usual drink is water, that I had been little accustomed to take wine or spirits, and had never been compleatly intoxicated but once before in the course of my life. This will account for the powerful effects of a single bottle of wine.
[217] The plan of this box was communicated by Mr. Watt. An account of it will be detailed in the Researches.
[218] The nitrous oxide was too diluted to act much; it was mingled with near 32 times its bulk of atmospheric air.
[219] In all these experiments after the first minute, my cheeks became purple.
[220] Physical pleasure and pain generally occur connected with a compound impression, i. e. an organ and some object. When the idea left by the compound impression, is called up by being linked accidentally to some other idea or impression, no recurrence, or the slightest possible, of the pleasure or pain in any form will take place. But when the compound impression itself exists without the physical pleasure or pain, it will awaken ideal or intellectual pleasure or pain, i. e. hope or fear. So that physical pleasure and pain are to hope and fear, what impressions are to ideas. For instance, assuming no accidental association, the child does not fear the fire before he is burnt. When he puts his finger to the fire he feels the physical pain of burning, which is connected with a visible compound impression, the fire and his finger. Now when the compound idea of the fire and his finger, left by the compound impression are called up by his mother, saying, “You have burnt your finger,” nothing like fear or the pain of burning is connected with it. But when the finger is brought near the fire, i. e. when the compound impression again exists, the ideal pain of burning or the passion of fear is awakened, and it becomes connected with those very actions which removed the finger from the fire.
[221] Notice of some Observations made at the Medical Pneumatic Institution.
[222] In some of these experiments, hearing was rendered more acute.
[223] Dr. Mitchill (an American Chemist) has erroneously supposed its full admission to the lungs, in its concentrated state, to be incompatible with animal life, and that in a more diluted form it operates as a principal agent in the production of contagious diseases, &c. This gratuitous position is thus unqualifiedly affirmed. “If a full inspiration of gaseous oxyd be made, there will be a sudden extinction of life; and this accordingly accounts for the fact related by Russel (History of Aleppo, p. 232.) and confirmed by other observers, of many persons falling down dead suddenly, when struck with the contagion of the plague.”