viii Contents 



under water and in a place free from air, p. 9. The flame of 

 nitre is produced by the igneo-aerial particles contained in 

 it, p. 10. But not by sulphureous particles, as nitre does 

 not contain such, p. 10. For the production of flame 

 sulphureous and igneo-aerial particles are required, p. 11. 

 Sulphureous matter cannot be set on fire without aerial 

 pabulum, p. 11. Why, for the kindling of nitre, it is not so 

 much air, as sulphureous matter, that is required, p. 11. 

 Why the flame of nitre is so impetuous, p. 12. The access 

 of external air promotes the kindling of nitre, p. 12. The 

 igneo-aerial particles contained in nitre seem to constitute its 

 aerial part, p. 13 ; see pp. 82 and 83. The aerial and igneous 

 part of nitre exists in the spirit of nitre, p. 13. The spirit of 

 nitre is compound, derived partly from terrestrial matter, but 

 also partly from the air, p. 13. Why the igneous particles of 

 air should be called nitro-aerial spirit, p. 14. The caustic 

 character of the spirit of nitre arises from its aerial part, 

 namely, from its igneo-aerial particles, p. 14. Why that 

 spirit, in distillation, appears of a ruddy colour, p. 14. 

 Why spirit of nitre does not go on fire although it contains 

 igneous particles, p. 14. 



CHAPTER III.— Of the Nature of Nitro-A£rial 

 AND Igneous Spirit. 



It is shown that the igneo-aerial spirit is of a nitro-saline 

 character, p. 16. Yet the igneo-aerial salt is neither acid 

 nor alkaline, p. 16, The form of flame chiefly depends on 

 the nitro-aerial particles, p. 16. It can be produced from a 

 certain kind of particles only, p. 17. What part the sulphu- 

 reous particles take in the production of fire, p. 17. What is 

 the essence of fire, p. 18. The caustic nature of spirit of nitre 

 and of flame arises from the same igneo-aerial particles, p. 18. 

 Why we think of the sulphureous rather than of the aerial 

 particles as burning, p. 19. It is shown by experiments that fire 

 is especially produced by nitro-aerial particles, p. 19. On the 

 fire produced by the rays of the sun concentrated by means 

 of a mirror, p. 20. Why antimony calcined by the solar 

 rays becomes diaphoretic and increases in weight, p. 20. 



