From several of the foregoing circumstances, we are justified in considering tobacco closely allied to intoxicating liquors, and its confirmed votaries as a species of drunkards. At least, it is certain that, when used to excess, it gives birth to many of the corporeal and mental manifestations of ebriety. VI. _Modified by Nitrous Oxide._—The drunkenness, if it merit that name, from inhaling nitrous oxide, is likewise of a character widely differing from intoxication in general. This gas was discovered by Dr. Priestley, but its peculiar effects upon the human body were first perceived in 1799, by Sir Humphry Davy, who, in the following year, published a very elaborate account of its nature and properties, interspersed with details by some of the most eminent literary and scientific characters, of the sensations they experienced on receiving it into their lungs. According to these statements, on breathing the gas the pulse is accelerated, and a feeling of heat and expansion pervades the chest. The most vivid and highly pleasurable ideas pass, at the same time, through the mind; and the imagination is exalted to a pitch of entrancing ecstasy. The hearing is rendered more acute, the face is flushed, and the body seems so light that the person conceives himself capable of rising up and mounting into the air. Some assume theatrical attitudes; others laugh immoderately, and stamp upon the ground. There is an universal increase of muscular power, attended with the most exquisite delight. In a few cases there are melancholy, giddiness, and indistinct vision; but generally the feelings are those of perfect pleasure. After these strange effects have ceased, no debility ensues, like that which commonly follows high excitement. On the contrary, the mind is strong and collected, and the body unusually vigorous for some hours after the operation. At the time of the discovery of the effects of nitrous oxide, strong hopes were excited that it might prove useful in various diseases. These, unfortunately, have not been realized. Even the alleged properties of the gas have now fallen into some discredit. That it has produced remarkable effects cannot be denied, but there is much reason for thinking, that in many cases, these were in a great measure brought about by the influence of imagination. Philosophers seem to be divided on this point, and their conflicting testimonies it is not easy to reconcile. Having tried the experiment of inhaling the gas myself, and having seen it tried upon others, I have no doubt that there is much truth in the reports originally published of its properties, although in many cases, imagination has made these appear greater than they really are. The intoxication which it produces is entirely one _sui generis_, and differs so much from that produced by other agents, that it can hardly be looked upon as the same thing.