564- Intelligence and Miscellaneous Articles. 



'& 



Now, if the phosphoric acid in ledererite is united with lime as an 

 accidental mixture, '2\ per cent, of the lime should he taken from 

 the 11*48 per cent, found in the mineral: this brings the proportion 

 down nearly to that obtained by Connell. Mr. Hayes was not able to 

 determine the weight of the water with accuracy, owing to the small 

 quantity of the mineral operated upon. As the loss (1*44 per cent.) 

 was mostly water, we may suppose, with Rammelsberg, that ledererite 

 is gmelinite containing \ (\ ?) its quantity of water. The chemical 

 formula for gmelinite and chabasite is thus : 



(CaO, NaO, 3KO )2 SiCP + 3 APC-s 2Si03 + 1 8HO*. 



Excepting the absence of striae, and the shorter dimensions of the 

 prismatic planes of its crystals, the Irish gmelinite precisely resem- 

 bles ledererite ; their hardness, lustre, colour and blowpipe charac- 

 ters are the same. The appearance of hexahedral cleavage, on which 

 Dr. Jackson originally founded the chief claim of the latter to the 

 character of a new species, was only imperfectly produced by heat- 

 ing the crystals, and not by ordinary mechanical cleavage. This 

 could not be effected, the mineral breaking in all directions with a 

 vitreous fracture. Dr. Jackson agrees with me that it can no 

 longer be retained as a distinct species. 



While preparing my edition of Phillips's Mineralogy, I requested 

 Mr. Hayes and Dr. Jackson to make several analyses for me with 

 particular reference to that work. As some of these have not ap- 

 peared in any other form, I wish now to make a permanent record 

 of them, in order that they may be seen where they might not other- 

 wise reach. The first are of the Nova Scotia chabasite (acadiolite), 

 which Hoffmann has distinguished from common chabasite, by its con- 

 taining three per cent, more silica, and for which Rammelsberg has 

 given a formula differing somewhat from that of chabasite. (See 

 first part of this article.) 



52-20 



18-27 



6-58 



2-12 



20-52 

 99-60, Hayes. 99*69, Hayes. 



These results[agree with those obtained by Hoffmann f in his analy- 

 sis of the same mineral, the specimens of which were presented to 

 him by Charles Cramer, Esq. of St. Petersburg. 



by the editors of the Amer. Journ. of Science, may be seen at the pages here 

 referred to. 



* Handw'6rterbuc7i,\. 150. Rammelsberg unites chabasite and gmeli- 

 nite, the first as soda chabasite, the last as lime chabasite. This is in 

 accordance with Tamnau, who has established their identity on crystallo- 

 graphical grounds. The close relation of the two minerals was, however, 

 first shown by Prof. Mohs. See his Mineralogy, vol. ii. p. 105. 



t Amer. Journ. of Science, vol. xxx. p. 366. 



