and Remarks on, the Mineral Species T)/rite. 



95 



TjTite, 

 Hampemyr, 

 D. Forbes. 

 Columbic acid . . 4490 



Yttria 29-72 



Lime 0-81 



Protoxide of cerium . \k.ok 

 Protoxide oflanthauium J 



Protoxide of iron 

 Protoxide of uranium 

 Binoxide of tin . . 

 Alumina .... 

 Zirconia with glucina 

 Water 



6-26 

 3-03 



5-66 

 trace 

 4-52 



Tyrite, Fergusonite. 



Helle, Greenland, 



D. Forbes. Hartwall. 



44-48 (tantalic) 47-75 



27-83 41-91 



1-68 



5 -631 



1-47J 



4-68 



2-11 (sesquioxide)0-34 



100-25 



5-99 

 trace 

 3-55 

 2-78 

 4-66 



100-18 



do. 



0-95 

 1-00 



3-02 

 trace 



99-65 



From this it will be seen that there is a very considerable 

 difference in the amounts present of the various elements. In 

 Fergusonite Berzelius and Hartwall found a trace of water, con- 

 sequently were not ignorant of its existence, so that M. Kenn- 

 gott cannot with propriety refer to this with the remark, " dass 

 man sie gar nicht fand, wenn man sie nicht suchte ;" and if he 

 consulted the original memoir of M. Hartwall, he has quite 

 forgot to insert in his communication M. Hartwall's observation, 

 that we may with certainty regard water as not entering into the 

 chemical constitution of Fergusonite'^. 



There can be no doubt as to the water in Tyrite being essen- 

 tial to its constitution ; and the determination of water as given 

 in the analyses is probably below the real amount, as the mine- 

 ral appears to oxidize on heating, which makes the loss less than 

 it otherwise would be ; for this reason, it was found that the 

 amount of water was greater when the mineral was heated in 

 fragments than when heated in powder, and the length of time 

 also was of importance. 



When well crystallized, the mineral on heating decrepitated 

 often very strongly, and on losing its water sometimes suddenly 

 fell entirely to powder, having a tine greenish-yellow colour. 



Many determinutions were made of the water, and the average 

 of all was 480 ; but this is probably too low, as several of 

 them were made on the finely powdered mineral heated for a 

 considerable time, and which consequently showed less than 

 otherwise. 



The differences in the quantities of the other elements is at 

 once seen by reference to the tabulated results. It is not. 



♦ Koi^l, VeU Acad. Handl. 1828. p. 170. 



