118 On two doubtful British Species, Glottalite and Zeuxite. 



I used the greatest care in obtaining the alkalies separately, 

 and have no doubt that the numbers just given accurately repre- 

 sent their relative proportions. It is to be regretted that Mr. 

 Jennings did not obtain from Mr. Campbell a complete analysis, 

 as perfect confidence cannot be placed in quantitative results if 

 all the constituents be not weighed ; but if we agree to accept 

 Mr. CampbelFs determination of the alkalies as perfectly correct, 

 it is as wholly irreconcileable with Sir Robert Kane's statement 

 as any that has been produced during the controversy. 



I regret particularly that Sir Robert Kane has left this question, 

 so far as he is concerned, without any means of solution. And 

 as those who are competent to decide . such questions naturally 

 withhold their judgement till all sides are heard, I hope I may be 

 excused if in these pages I express the hope that ere long Sir 

 Robert Kane will favour the public with the investigations on 

 which he has based his opinion. I may, no doubt, be in error 

 in some of my views of this question ; and if so, would be glad 

 to have my mistakes corrected by so competent an authority. 

 I remain. Gentlemen, 



Your obedient Servant, 



Trinity College, Dublin, JosEPH A. GalbraitH. 



July 16, 1855. 



XVI. On two doubtful British Species, Glottalite and Zeuxite. 

 Bt/ R. p. Greg, Esq.* 



IHA\T] lately had an opportunity of seeing the original spe- 

 cimens from which, many years ago, the late Dr. Thomson 

 described the rather doubtful species Glottalite and Zeuxite. 



1. The Glottalite occurs both crystallized and massive. The 

 massive much resembles, as indeed Dr. Heddle lately suggested 

 it might be, edingtonite. The crystals, which Dr. Thomson 

 rather loosely described as "having nearly equilateral faces, 

 either four-sided pyramids or regular octahedrons," are without 

 doubt chabasie. The crystals, though not easy to distinguish, 

 occur in double six-sided pyramids, a form of chabasie sometimes 

 also called phacolite. Another proof of its being in all probability 

 chabasie is the fact, that glottalite is described by Thomson as 

 containing 21^ per cent, of water, which is exactly the proper 

 proportion for chabasie. 



2. Zeuxite. — This mineral I have long considered as merely 

 a tourmaline or schorl, and my inspection of Dr. Thomson's 

 specimen only confirms me in that opinion. At the time the 

 specimen was found, viz. in 1814, at Huel Unity, little was then 

 known comparatively of the precise composition of tourmaline, 



* Communicated by the Author. 



