232 Scientific Intelligence. 
Dr. Hawes next gives the result of a calculation by him of the 
mineral constitution of the West Rock trap from the above ele- 
ments, which is as follow 
“Anorthite 15° 52, aibits 22°16, potash feldspar 2°32, augite 
54°47, titanic iron 2° 68, magnetite 1: 76, apatite 0°32, total 99°23.”* 
Dr. Hawes thus makes out that the feldspar of the J ersey City 
trap consists of labradorite and feldspathic material having the 
ratio of aie while that of West Rock consists chiefly of 
anorthite and albite. 
his extraordinary result for the West Rock ue and its 
so wide divergence from that for the Jersey City trap make it 
important to consider carefully the details in the calculation. It 
is the more marvellous since Mr. Hawes’s analyses of the Jersey 
City and West Rock traps, in his former paper, gave them very 
nearly the same chemical constitution. We cite the analyses 
together for comparison, along with another (from the same paper) 
of a trap from intergreen Lake, which adjoins West Rock. 
SiO. Big0;. Fes0; Feo MnO MgO 
y City 6813" 1974 1:08 "9:10 =. 043 BS 
2. West Rock 5178 . 1420 359 825 044 63 
3. Wintergreen Lake____- 52°42 «14:54. a1250s 984 iH Ss TB 
CaO N K,0 P20; Ign. 
O Jersey ms 9°47 230 ~~ 1°03 pode 0:90 ae 99°76 
2: Went Roe ius bok. 10°70 214. O39 4014 063 = 99°89 
3. whim Lake jus: 10°59. 223 = 0-49 ae, OSB ee OON8 
. Hawes’s citation of the West Rock eile (see above) 
he deagnts 1°41 from the alumina, reducing 14°20 to 12°79, on the 
ground of the aap finding of this amount of titanic acid in it by 
: e; and if right in this, some similar deduction 
would probably have to be made for the rock of the other local- 
itie 
Ne w analyses ee would have afforded a surer basis for 
a calculation. But e with these, a different treatment of the 
nee EA ee have bent pounded for right conclusions. 
the Jersey City rock i Bp: es eighty Ge apart), tats no foarte 
on the composition ot the latter, except by way of suggestion. f 
Further: the “ anorthite i in West Rock,” of which he gives the 
The anorthite is in isolated crystals about three inches ap@ 
* The numbers for the anorthite and albite should be transposed. 
