80 Count de Bournon on the Laumomle, 



in which disintegration had commenced, having a dull white appear- 

 ance, and opaque, but not sufficiently changed to break and divide of 

 itself, did not shew any sensible difference with respect to this 

 character. 



2. Hardness. When the laumonite has not been altered, it cuts 

 glass with ease ; but in proportion as it becomes disintegrated, this 

 hardness diminishes, and ultimately the least pressure reduces it 

 into small delicate prismatic fragments. 



3. Electricity by friction. None. 



C. CHEMICAL CHARACTERS. 



1. Action of acids. This substance is reduced to the state of a 

 jelly by the action of acids. 



2. Action of heat. Under the blowpipe, and without addition, 

 the laumonite is fusible with a slight degree of ebullition, and affords 

 a perfectly opaque and beautifully white enamel. 



3. Analysis. As far as my knowledge extends, no analysis has 

 yet been made by which the constituent parts of this substance have 

 been determined. 



4. Natural alteration. This character is so peculiar, so striking, 

 and so constant in this substance, that it is perfectly entitled to be 

 placed in the number of its essential specific characters. From the 

 moment that the laumonite is exposed to the atmosphere, it begins 

 to alter, and this alteration, as well as the progress of it, is propor- 

 tional to the warmth of the air; it advances with such rapidity 

 when the temperature is high, that having inadvertently undertaken 

 during a very hot day the examination of its crystals, many of these, 

 in which the alteration, although begun, was not yet very consider- 

 able, so quickly disintegrated that it became impossible, even in 



