An old and still very popular treatment--said to have been introduced by an American, Nicholas Frisi,[24] in 1843--consists of the inhalation of the fumes of burning saltpetre or in smoking cigarettes made of paper which has been soaked in a saturated solution of that substance. Inhaled into the bronchi, it is supposed to act as an anæsthetic, and produces relaxation of the constricted bronchial muscles. In point of efficiency these inhalations rank quite high, and are probably more generally used than any other remedy. Aside from the relief which they undoubtedly afford, this method derives much of its popularity from being within easy reach of the patient himself. The preparation of the papers is exceedingly simple: A sheet of bibulous paper is dipped into a saturated solution of the nitrate of potassa prepared with cold water; after drying it is divided into strips of the size required. These papers are burnt before the patient, the windows and doors of the apartment having been previously closed to prevent the escape of the fumes. Nitrate of potassa has been prepared in a variety of other ways for the use of asthmatic patients, one of the most convenient of which is the Kidder pastilles so extensively used in this country. Another method is to roll the paper prepared as above into cigarettes, the smoke of which is inhaled by the patient. The nitre is best used early in the attack, but is also beneficial when the paroxysm is at its height. The efficacy of this treatment is attributed by Germain Sée to the formation of protoxide of nitrogen and carbonic acid gas, which act as an anæsthetic, and perhaps also to the particles of carbon in the smoke floating in the air, a smoky atmosphere being beneficial to many asthmatics. [Footnote 24: Germain Sée, _op. cit._, p. 709.] The smoking of the Datura metel having been found efficacious in asthma in India, Anderson of Madras in 1802 sent some of the leaves to Gen. Gent, an English officer, by whom they were introduced into England. Simms of Edinburgh, believing that the Datura stramonium might prove equally good, tested it with such good results that it soon came into general use, not only in asthma, but in other forms of dyspnoea. This is the ordinary Jimson or Jamestown weed which is so widely distributed over the Southern, Middle, and Northern States, and, like nitrate of potassa, is much used, not only by the profession, but largely as a household remedy for asthma. The dried leaves are either smoked in a pipe or in the form of a cigarette. The effects, however, are quite uncertain, sometimes acting like a charm, while at others it affords no relief; its physiological action is that of a sedative. Of late years another species of Datura has been introduced--the Datura tatula. Its properties and uses are similar to those of stramonium, but it is supposed to be less narcotic.