Page:Transactions of the Geological Society, 1st series, vol. 1.djvu/92

 80 in which disintegration had commenced, having a dull white appearance, 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..

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 proportional 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 considerable, so quickly disintegrated that it became impossible, even in