Chap, 2.3 "Phenomena cf Evaporation. 107 



fluid, and yet the temperature or obvious heat of the 

 fluids is not increafed, as may be proved by the ther- 

 mometer ; wherefore it is plain that the caloric exifts 

 in thefe fubftances in a latent or combined Hate. 



4thly. The matter of fire is elaftic, as is proved 

 evidently from all its effects. There is indeed reafon 

 to believe that caloric is the only fluid in nature which 

 is permanently elaftic, and that it is the caufe of the 

 elaflicity of all fluids whiclt are efteemed fb. 



From the elafticity of this element it refults that all 

 natural bodies can only retain a certain quantity of it, 

 without undergoing an alteration in their ftate and 

 form. Thus a moderate quantity of fire admitted into 

 a folid body expands it ; a ftifl larger quantity renders 

 it fluid j and if the quantity is ftill increafed, it will 

 be converted into vapour. But this, and all the other 

 properties of caloric, will be better underftood from 

 its effects. Let it fu.^ce to remark for the prefent, 

 that moft fluids may be converted into a flate of un- 

 ufual rarity, by the acceflion cf fire. Vapour is 1,800 

 times lefs dcnfe than water ; and thofe matters which 

 have a ftronger attraction for fire may by the fame 

 means be converted into fluids permanently elaftic. 

 The nitrous acid is wholly convertible into two fpe- 

 cies of air, oxygen and azote, or pure and phlogifti- 

 cated air ; and oils, refins, charcoal, and other inflam- 

 mable matters, will by the application of heat readily 

 the form of inflammabfc air. 



