736 Scientific Proceedings, Royal Dublin Society. 
After careful examination and measurement of the middle 
edges of the first-mentioned mineral it was set down as anatase. 
The density was determined, and gave a mean result of 3°587, 
which is distinctly lower than that of anatase proper, which is 
given in Zirkel’s “ Mineralogy,” as 3°83 to 3-93. 
It is to be remarked, however, that it was very difficult to obtain 
crystals so perfectly free from adhering parts and particles of quartz, 
as to allow of their being taken as perfectly pure. Hence, how- 
ever careful the hand-picking, some adhering quartz remained on 
the crystals examined for density. This, of course, operated to 
lower “ pro tanto” the density below the normal figure. In order 
to clear up this apparent discrepancy, a sufficient sample of hand- 
picked crystals was entrusted to Mr. W. L. Warren, F. C.S. for 
careful analysis. His report gave the composition of the crystals 
(No. 1) as below. Thinking that the alumina therein shown 
might have proceeded from minerals which had either accompanied 
the sample, or were adherent to the erystals as hand-picked, a 
further portion was very carefully hand-picked under the lens and 
this further sample entrusted by me to Mr. Warren, who reported 
as composition the analysis (No. 2) as below. 
(No. 1). (No. 2). 
Percentage. Percentage. 
Si0., . S : 3°30, 4 ‘ ‘4 3:07 
AleoOs, . : = l22865 : 5 =) 13:02 
HeO are . = | Lo7205 = : . 10°40 
Fe203, . s : 1°05, : 3 4 6:01 
C205 : : 2°29, tee 6 5 2°16 
MgO, . : 5 4°42, : 2 4°42 
WinQe seu) Me . traces : : . traces 
Wi@y, : a O02: 6 ; . 60°81 
(K20 and Na2O) . 0-06, 0 é : 0°12 
Combined Water, . 0-06, 5 ‘ : — 
99-96 100°01 
The main difference from one sample to the other was in the 
iron; and it was concluded that the alumina found was present as 
an essential constituent of the mineral. 
Assuming this for the present, it is evident that the composition 
shown is different from that of any known Silico-titanate, such as 
mentioned by Dana in his “ System of Mineralogy ” (edit. of 1892), 
and, if confirmed, may represent a new mineral, or mineral variety, 
