J. Lawrence Smith on Emery. - 68 
The oxyd of iron may be regarded as an impurity which exists 
between the plates of the mineral. The composition of the 
emerylite is represented if 
Atoms. At. Weight. Pratt Oxygen ratio. 
Lime, 2 700: 13:48 2 
Silica, 3 1700-1 32:74 9 
Alumina, 4 2566°5 49-44 12 
Water, 2 225° 4:34 2 
5191-6 
Formula, 2 Si-+2Al2 Si+2H, 
As is seen, the specimens examined came from four distinct local- 
ities, and were all taken under different cireumstances ; yet their 
analyses accord perfectly, and also agree with those of the United 
States coming from Village Green and Unionville of Pennsylva- 
nia, and Buncombe County, North Carolina.* 
Localities. Silica. | “ale |Lime, Mague-| - otal) Water. 
Village Green, 32°31 |49°24/1066 030 | 221 | 527 | =100 Craw: 
™ 31-06 |51:20 9-24 0-98 | 2-97 | 5-27 | =100 Craw 
e 31:26 |51°60)10°'15; 0°50 | 1:22 | 427 | =100 raw 
Pte 30°18 |51°40/10°87/ 0°92 | 27 ‘B2 | =100-46 Craw. 
Unionville,. ..| 29-99 |50°57/11°31) 072 | 247 | 514 | =100710 pai 
« . ; onl not es- po. arts- 
32°15 |54:28/11°36) 0°05 itimat’d 0:50 |e trace, hi one 
ELbe- 
Buncombe Co.) 29°17 |48-40} 9:87| 1:24 | 615 | 3:99 HF 2°08 =100°80| ig 
My analyses were made in the ordinary way, only with more 
carbonate of soda than is usually employed. The alkalies were 
Separated either by means of hydrofluoric acid or by carbonate of 
lime, which is preferable to the carbonate of baryta for the de- 
_ It is seen that potash and soda are present in small quantities : 
inall the specimens. The composition © this mineral is re- 
corundum crystallizes, the silica finding itself in presence with an 
excess of bases, combines with as large a quantity as 1s affinity 
will admit of. In speaking of the formation of emery, I have 
already alluded to a nodule in my possession that exemplifies this 
in a Very exact manner. 
