1823.] Crystalline Form of some new Minerals. 383 



the solution crystals of sulphate of magnesia, tasting, however, 

 very strongly of iron. 



"there was no residuum except a small quantity of the talc 

 which penetrated the fragment I examined,* and the solution 

 gave no trace of lime ; the mineral appears, therefore, to be a 

 carbonate of magnesia and iron. 



Ten grains kept for some time at a red heat lost 4*82, and the 

 colour became a snufF-brown. 



Ten grains dissolved in dilute muriatic acid left a small inso- 

 luble residuum, apparently of the talc in which the mineral is 

 imbedded. A few drops of nitric acid being added toperoxidate 

 the iron, a precipitate was obtained by succinate of ammonia, 

 which, when washed, and heated to redness, to destroy the suc- 

 cinic acid, weighed 1 gr. 



From this experiment, the mineral might consist of 1 atom of 

 carbonate of iron, and 9 atoms of carbonate of magnesia. 



For if to the . apparent loss by heating 4*820 



we add the increase occasioned by the peroxidation of 

 the iron, we shall have the true weight of the matter driven 

 off. 



1 gr. peroxide of iron, equivalent to •815 protoxide, 



difference 0*185 



5*005 



0-815 protox.ofiron requires of carbonic acid for saturation 0*500 



0*500 carbonic acid T „ , . , , . .. 77777 



If this be carbonic acid 4*505 



it would require of magnesia for its 



saturation 4*100 



1*315 carb. iron 

 8*605 carb. mag. 



9*920 Giving carbonate of magnesia 8*605 



If we consider 7*25 as the equivalent for carbonate of iron, and 

 5*25 as that of carbonate of magnesia, we should have 



7*25 : 5*25 :: 1*315 : 0*95 nearly 

 And 0*95 : 8*605 :: 1 : 9 nearly. 



But a more accurate analysis might possibly vary these propor- 

 tions. 



Latrobite. — It is to the Rev. C. I. Latrobe that I am indebted 

 for specimens of the mineral to which I have given this designa- 

 tion. And mineralogy is also indebted to him for the researches 

 he has himself made, and caused to be made by others, in remote 

 districts seldom visited by Europeans. 



The mineral in question came from Amitok Island near the 

 coast of Labrador ; it is accompanied by mica and carbonate of 



» The true bitter spar leaves a pulpy residuum of sulphate of lime when dissolved in 

 dilute sulphuric acid. 



