2 



weight, and takes up caloric, or latent heat of Dr. Black. It 

 is then caustic, with the properties as described in the generic 

 character, changing the syrup of violets green. This 

 character it retains as long as the latent heat or the effect 

 of it lasts, which heat and principle of changing the syrup 

 of violets green will be lost if exposed to a damp atmosphere. 



The upper figure is done to express artificial lime just ex- 

 posed to damp air, yet capable of changing the syrup of 

 violets green, and beginning to fall to pieces. If a quantity 

 is suddenly added, it will lose its characteristic property 

 sooner, by absorbing carbonic acid gas from the atmosphere, 

 or the water of which the fire had deprived it in the kiln, 

 and when dried without heat will be nearly what it was at 

 first. 



The middle figure, Calx nativa, from Bath, has qualities 

 resembling quick-lime, and changes syrup of violets to a 

 green, nearly as vivid as that produced by the artificial lime 

 above; and although I have had it two years in the drawer 

 with quick-lime, it still gives a green which the other does 

 not. 



The lower figure represents lime taken out of a hollow 

 nodule of flint, to which, before it was broken, we could 

 find no apparent aperture. The contents were exposed im- 

 mediately to some fresh violet petals, pressed so as to afford 

 two or three drops of purple fluid, which it directly changed 

 green. It soon lost that property, and is now a gritty chalk. 



