150 W, F. Hillebrand — Composition of Yttrialite. 



Nitrogen (?) and helium (?) were obtained quantitatively by 

 fusing the mineral with sodium-potassium carbonate in a cur- 

 rent of carbon dioxide and collecting the gases in a nitrometer 

 over potassium hydroxide. The volume was between one and 

 two cubic centimeters per gram of yttrialite. The gases were 

 not further examined. 



The analysis is given above, together with that of Mackintosh 

 for comparison. 



The ratios of Mackintosh's analysis as calculated above by 

 me are certainly wrong in so far as they are affected by the 

 value for iron, which he assumed to be wholly ferrous. If 

 corrected in accordance with the statement of my analysis, or, 

 what amounts to the same thing for the purpose of illustration 

 and is simpler, if my ratio is altered to conform to his state- 

 ment for RO and R 2 3 bases it becomes '0644: : -1882, a very 

 close agreement. 



It is altogether probable that Mackintosh's separations of the 

 earths were not so far reaching as mine, and this belief is borne 

 out by the differences in the experimental molecular weights 

 for the lanthanum and yttrium groups, mine being more in 

 accordance with what might be expected and, moreover, agree- 

 ing almost exactly with those which were found by me for 

 rowlandite in 1893, namely, 336*8 and 266*2 respectively.* 



It is of course impossible to say what disposition should be 

 made of the small amounts of firmly held water, phosphorus, 

 carbon dioxide, fluorine, and alkalies. The ratios of my 

 analysis are, therefore, to a slight extent incorrect, but prob- 

 ably not enough to influence any conclusions that may be 

 drawn. One thing is apparent, that the preliminary purifica- 

 tion by acid has had no pronounced effect on the composition 

 of the mass acted on, otherwise Mackintosh's and my analyses 

 should show far greater differences in the main constituents. 



The crude empirical formulas deducible from the ratios of 

 the two analyses are nearly 



* The three minerals gadolinite, yttrialite, and rowlandite occur in Llano 

 County in most intimate association, suggestive of close community of origin, a 

 suggestion which is emphasized by the marvelous agreement for gadoliuite and 

 yttrialite, not only in the relative proportions of the trivalent earth metals but in 

 their absolute amounts as well. 



Ce 2 3 La 2 3 , etc. Y 2 3 , etc. 



Gadolinite (G en th) 2-65 5 22 44-35 



" " 2'66 5-01 44-45 



(Eakins) 2-62 5-22 4155 



Yttrialite (Ei'b'd.) 307 5-18 43'45 



Rowlandite ( " ). ..5-06 9-34 47-70 



This concordant testimony of three analysts may be regarded as strong evi- 

 dence of the correctness of the earth separations made by them in these cases. 

 Nearly the same relation is shown by the trivalent earth-metals of rowlandite, as 

 seen in the table above. 



