DOMAIN XI. DECOMPOSED. 



see Zimmerman's account of this native 

 nitre. (36 Roy. 111,113, and 1 Klap. 319-) 

 " So also when the calx of iron contain- 

 ed in stones is but slightly oxygenated, it 

 may, by reason of the close texture of the 

 stone, remain undecomposed for ages ; but 

 if by any accident, as fracture, or contact 

 with some saline matter, or the alternate 

 reception and dismissal of water, the re- 

 ception of more oxygen is facilitated, a de- 

 composition will commence, which, as in 

 the former case, will spread like a caries, 

 because the less oxygenated part of the 

 iron takes oxygen more easily from the 

 more oxygenated part, than from the at- 

 mosphere ; by reason, that the absorbed 

 oxygen is more condensed than it is in the 

 atmosphere. Thus iron inserted into a 

 highly oxygenated solution of vitriol of 

 iron, and which therefore refuses to crys- 

 tallise, will take up the excess of oxygen, 

 and thus restore the solution to a crystal- 

 lisable state ; or as calx of tin takes up 

 oxygen from calces of silver, antimony, c. 



