376 On the Constitution of Philipsite^ or Lime Harmotome, 



3.13, — differences which, as the amount of the other consti- 

 tuents is much the same in all the cases, render it scarcely 

 possible to represent all the results by the same formula. 



It therefore appears to me that this part of the subject 

 affords room for farther investigation ; and as a contribution 

 to that end, an analysis of the Philipsite or lime-harmotome of 

 the Giant's Causeway will perhaps not be unacceptable. 



The specimen examined was in well-sized white and trans- 

 lucent twin crystals of the ordinary harmotome form. Their 

 sp. gr. was found to be 2.17, at 61°. 



A portion of the crystals lost by ignition 16.96 per cent, of 

 water. 



20 grains in fine powder were treated with strong muriatic 

 acid, when immediate gelatinization took place ; and, by the 

 usual steps of analysis, there were obtained, — 



nJ 



This would give the formula 2 K V S2 + 6 AS^ + 9 Aq. 



nJ 



This result differs materially in regard to the amount of 

 the one-atomed bases from those of Kbhler, and approaches 

 more nearly to those of Gmelin and Hepel, particularly to one 

 of their results ; the proportion of the oxygen in which in- 

 stance, will admit of being expressed by the above numbers, 

 almost as well as by any others, or at least will thus yield the 



