With regard to the uses of these new compounds it is difficult to form a guess. When they are obtained pure, and fully saturated with nitrous oxide, on account of the low temperature at which their gas is liberated, they will probably constitute detonating compounds. From their facility of decomposition by the weaker acids, they may possibly be used medicinally, if ever the evolution of nitrous oxide in the stomach should be found beneficial in diseases. XII. _The properties of Nitrous Oxide resemble those of Acids._ If we were inclined to generalise, and to place nitrous oxide among a known class of bodies, its properties would certainly induce us to consider it as more analogous to the acids than to any other substances; for it is capable of uniting with water and the alkalies, and is insoluble in most of the acids. It differs, however, from the stronger acids, in not possessing the sour taste,[165] and the power of reddening vegetable blues: and from both the stronger and weaker acids, in not being combinable when in a perfectly free state, at common temperatures, with the alkalies. If it should be proved by future experiments, that condensation by cold gave it the capability of immediately forming neutro-saline compounds with the alkalies; it ought to be considered as the weakest of the acids. Till those experiments are made, its extraordinary chemical and physiological properties are sufficient to induce us to consider it as a body _sui generis_. [165] The different persons who have respired nitrous oxide have, as will be seen hereafter, given different accounts of the taste; the greater number have called it sweet, some metallic. One of my friends, in a letter to me dated Nov. 13, 1799, containing a detail of some experiments made on the respiration of nitrous oxide, at Birmingham, denotes the taste of it by the term “sweetish faintly acidulous.” To me the taste both of the gas and of its solution in water, has always appeared faintly sweetish. It is a singular fact that nitrous gas, which contains in its composition a quantity of oxygene so much greater than nitrous oxide, should nevertheless possess no acid properties. It is uncombinable with alkalies, very little soluble in water, and absorbable by the acids. DIVISION II. _On the DECOMPOSITION of NITROUS OXIDE by COMBUSTIBLE BODIES. Its ANALYSIS. OBSERVATIONS on the different combinations of OXYGENE and NITROGENE._ I. _Preliminaries._ From the phænomena mentioned in Res. I. Divis. III.[166] it appears that the combustible bodies burn in nitrous oxide at certain temperatures. The experiments in this Division were instituted for the purpose of investigating the precise nature of these combustions, with a view of ascertaining exactly the composition of nitrous oxide. [166] Section 2.