J. D. Whitney on Pectolite. 207 
tions will give a perfectly pure silica, but not all of it, as two or 
three per cent will still remain in the solution, a part of which 
will go down with the ammonia precipitate, and the remainder 
nd after driving off the ammoniacal salts, (the lime having 
been previously separated,) and igniting the residuum. 
The following are the results of three analyses of as many 
different specimens of the pectolite from the Bergen Hill tunnel. 
: I IL. Im. 
ee 54°82 54°76 54°27 
a, . " - - - $3:12 82°88 82°83 
rotoxyd of manganese, 66 : . 
Protoxyd of iron, - + ‘26 ae } des: 
ay Ee ae 8:78 9°17: 8-94 
Water, by loss, oe * ees 2°03 2°72 
£ 100°00 100-00 100°00 
t The direct determination of the water on the substance dried 
80°C. gave, for 11, 3°03, and for 111, 2°75 percent. Specimen 
_ il, from the Wheatley Collection, Union College, was Hypa 4 
i purest; it was a fragment of a mass, the fibres of whic 
___ Were several inches in length, slightly divergent from a common 
‘Centre, and being nearly transparent and evidently quite free 
any admixture with quartz or any other foreign substance. 
In analysis 111 the oxygen is as follows: 
Silica,  - : : : : 28-942 
Lime, i FS . - - 9°379 
: a z - - 2°306 
Protoxyd of manganese, -  - - 290 
Water, - - - - - 2°44 
This gives as the Tatio :* 
Ee ac Ok ee A ee 
Pee PP ae 
If we attempt to express this ratio by a formula, we have 
Na? Sit + 4003 Si2 + SH. 
a eteentage demanded by this formula is given below, by 
~ Se of that required by Von Kobell’s. 
4a Whitney. Von Kobell. 
We 6425 me a OS 
Poe ee ee ee ee * ee 
+ - - - 933 - - OTT 
ON oe sit Cig ey 2 A: SES : 
— y lisevident, t isot i 
4 t, from a comparison of the figures given above, 
: “atthe formula now suggested agrees more nearly with the re- 
a . : . . 
The atomic Weights used are as follows: 
‘Na=23 : Ca=20 : Si=21, H being =1. 
