310 Observations on the occasional Appearance of Water 



of ensuring to INI. Amici a just reward, it ought to be thought 

 upon ; for such is the simphcity of this instrument, that, its 

 description once given to the public, it may every where be 

 executed. M. Amici's is so much the more worthy of praise, 

 as he seeks not his own advantage by his invention, which he 

 readily gives to the public. What reward was given to Had- 



ley I know not; but will not offer us the opportunity 



to search into this accompt, and to gratify ourselves with the 

 comparison." 



LVI. Obsetyations 07i the occasional Appearance of Water in 

 the Cavities of regular Crystals ; and on the porous Nature 

 of Quartz, and other crystalline Substances, as the probable 

 Cause of that Occurrence. By John Deuchar, M.R.A.L 

 Edin., M. Cal. Hort. Sac., M. Wernerian Soc, O.P.A. Royal 

 Phys. Soc, and Lecturer on Chemistry in Edinburgh* 



AiMONG the numerous arguments which have been brought 

 forward by those who support the aqueous formation of the 

 globe, no one seems to bring with it greater force than that 

 which is drawn from the fact that water is often found inclosed 

 within the cavities of crystals of a regular shape. The ready 

 conversion of water into steam, and the expansive nature of 

 the steam when formed, even at a moderate temperature, would 

 lead us to conclude that crystals containing confined globules 

 of that fluid, could never have an igneous oi'igin. When we 

 examine the nature of such crystals, we often find them com- 

 posed of very infusible materials, such as quartz, the fluate of 

 Hme, &c. The intense heat requisite to bring quartz to the 

 state of fusion which would be necessary to enable it to cool 

 into regular crystals, must, if not counteracted by an immense 

 external pressure, have boiled the contained watei', and formed 

 an elastic agent so powerful that the texture of no known sub- 

 stance could resist it : but, as we cannot, when we examine the 

 situations in which" such crystals are found, discover the slightest 

 proof of any such external counteracting pressure, we are natu- 

 rally led to conclude that the whole must be the result of some 

 other mode of formation; and that theory which ascribes it to 

 crystallization from solution in water, seems satisfactory enough. 

 Those who maintain this latter o))inion have generally con- 

 tented themselves with explaining the circumstance upon the 

 su])position, that the particles of the substance in solution, du- 



* Read before the Wernerian Natural History Society, on Saturday May 

 19, 1821, and communicated by tlic Author. 



jing 



