66 
CONTRIBUTIONS TO MINERALOGY. 
[BULL. 262 
Nitrogen (?) and helium (?) were obtained quantitatively by fusing 
the mineral with sodium-potassium carbonate in a current of carba 
dioxide and collecting- the gases in a nitrometer over potassiJ 
hydroxide. The volume was between one and two cubic centimeter 
per gram of yttrialite. The gases were not further examined. 
The analysis is given above, together with that of Mackintosh id 
comparison. 
The ratios of Mackintosh's analysis as calculated above by me ai| 
certainly wrong in so far as they are affected by the value for iron 
which he assumed to be wholly ferrous. If corrected in accordanc 
with the statement of my analysis, or, what amounts to the same thin 
for the purpose of illustration and is simpler, if my ratio is altered t 
conform to his statement for RO and R 3 3 bases, it becomes .00441 
.1882 — a very close agreement. 
It is altogether probable that Mackintosh's separations of the cart! 
were not so far reaching as mine, and this belief is borne out by tl 
differences in the experimental molecular weights for the lanthanuii 
and yttrium groups, mine being more in accordance with what migl 
be expected and, moreover, agreeing almost exactl\ T with those wine; 
were found b}^ me for rowlandite in 1893, namely, 880.8 and 2$6'. 
respectively." 
It is of course impossible to sa}^ what disposition should be made'! 
the small amounts of firmly held water, phosphorus, carbon dioxid J 
fluorine, and alkalies. The ratios of my analysis are, therefore, to J 
slight extent incorrect, but probably not enough to influence anj 
conclusions that may be drawn. One thing is apparent, that the pi i 
liminary purification by acid has had no pronounced effect on t 
composition of the mass acted on, otherwise Mackintosh's and n| 
analyses should show far greater differences in the main constituent] 
The crude empirical formulas deducible from the ratios of the tNl 
analyses are nearly 
Hillebrand R" 01 R"' 3 86 R"" 47 (Si,0 7 ) 247 J 
Mackintosh R" R'" 
R"" 1S (SiAL 
a The three minerals gadolinite, yttrialite, and rowlandite occur in Llano County in most intin 
association, suggestive of close community of origin, a suggestion which is emphasized by the I f j 
velous agreement for gadolinite and yttrialite. not only in the relative proportions of the triva 
earth metals but in their absolute amounts as well. 
Gadolinite (Genth) 
Do 
Gadolinite ( Eakins) 
Yttrialite (Hillebrand)..-. 
Rowlandite ( Hillebrand) 
Y,0* ( 1 I 
This concordant testimony of three analysts may be regarded as strong evidence of the corred 
of the earth separations made by them in these cases. Nearly the same relation is shown b; 
trivalent earth-metals of rowlandite, as seen in the table above. 
