712 T. STERRY HUNT : SUPPLEMENT TO 
tive experiments upon these and other soluble lime-holding silicates. The influence of 
other bases, and the varying proportions of these will, probably, on farther investigation, 
be found of significance. Instead of a constant quantity of the various silicates compared, 
this might be varied with the unit-weights of the several species, which are, for example, 
for albite, 16.37; for orthoclase, 17.37; and for leucite, 18.16. 
Taste LX. — PROTOPERPHYLLOIDS. 




SPECIES. FORMULA. ES SDS AIX 
Astrophyllite. - |(m;m8ij)o);- - - - - - - - - |,..13.32| ...| 0. 
Phlogopite. - - | (myal,sig)o,. - (m,=mg;kes) - - |18.12| 2.85] 6.35| O. 
Pyrosclerite. - - | (mg,al,si,)o,, + 3aq- - - - - = |15.40| 2.74] 5.62| ©. 
Penninite. - - | (mgsçal.ç8is)Ops + 8aq - - - - |15.40| 2.67] 5.76| R. 
Ripidolite. - - |(mg;al;sis)o,, + 4aq - - - - - - |15,88| 2.70] 5.70} C. 
Prochlorite. - = | (m,alSié)Ou-c6 + 3aq - (m,—mpgife,)|17.72| 2.96| 5.98] H. 
Leuchtenbergite. | (mgy.;a]y.98i5-9)0\2-5 + 34aq - = - - [15.46] 2.65) 5.83) H. 
Venerite. - - - | (mym,si,)o,,+4aq - - - - - - |16.84| .… ? 
Corundophilite. - | (m,al,si,)o,,-+ 33aq - (m,— mg,fe,) |15.20| 2.90) 5.21! C. 
Biotite.- - - = |(mym,si,)0,,- (m,—mgs;kys) - - |18.18) 3.00) 6.06) H. 
Voigtite. - - - | (mymsi,)o,;,+4aq - (m,=meg,fe,) - [16.48] 2.91| 5.66) ? 
Cryophyllite.  - | (mgal,si,,)o,, - (m3—= fedalii) - - 17.90 2.91! 6.15} O. 
Seybertite. - - | (mgalysi;)o.) + 3aq - (m,—mg,ca,)- |17.97) 3.15) 5.70) O. 
Thuringite. - - | (fesmssis)o, + 6aq-(m,—al;fi,) - |19.56) 3.19) 6.18) ? 
Jefferisite.- - - | (mgemssi,:)o + 74aq - (m—=al,fi,) - |14.92, 2.80) 6.50) O. 
Annite.- - - - | (mgmpSijs)0j, - (ms =feske) - - - |20.84) 3.17| 6.57) ? 
Willcoxite. - - |(m,alsis)0:, + 2aq - (m,— mg:na,) |16.76| ...| ...| ? 
Chloritoid. - - |(fe,alssi,)o; + laq - - - - - - |18.00| 3.55) 5.07) C. 
Lepidomelane. - |(mym,sijo; - - - - - - - -|---/98.00)...) H. 
Zinnwaldite. - - | (myal,Sig)oj9- (M = kyliys) = - - |17-20) 3.00) 5.78) O. 
Oellacherite. - - | (mal,sig)oy +1aq -(m=k}ba}meg}) |17.33) 2.99) 5.79) ? 
Lepidolite. - = | (m-caly-;Sig-o)Oi-5 - (TA = Kyslig.;) - |16-85) 3.00! 5.61) O. 
Margarite. - - | (ca,alsi,jo, +laq - - - - - - |16.58) 2.99) 5.54) O. 
Euphyllite. - - | (mjal,Sig)o,g- (M=—ky.35naggs) - - [11:07 3.00) 5.69) ? 
Cookeite. - - - | (myalpSiy)o.9 +53aq - (M=lip.;ky-y;) |14-80) 2.70 5.48) ? 
Muscovite. - - |(kalsijos - - - - - - - - 17-75) 3.12) 5.68) O. 
Muscovite. - - |(kalsi)o,; + 2aq - - - - - - |16.77) 2.85) 5.88) O. 
Muscovite. - - |\(kalsipjon - - = - - = - - [LG27) ocr 0. 
Damourite. - - | (kj,alysi,,)ox-+2aq - - - - - - |16.58) 2.79) 5.94) O. 
Muscovite. - - | (kgsalgoSigo)0is5 = - = + - - - |16:80)-..]..-] O. 
Muscovite. - - | (KgsAlgoSig.9)0 55 +2aq - - - - {15-91) 2.75) 5.78 0. 




§ 11. Recent experiments with quartz crystals and sections of crystals show that 
while the crystalline planes are not visibly attacked by a strong acid of 54 per cent., cut 
and polished surfaces are corroded, their loss of weight in an hour’s time amounting in 
some experiments to five and six milligrams for the square centimetre of surface. The 
whole subject of the action of fluorhydric acid on mineral species, now under investiga- 
tion, promises, in the hands of Mr. Mackintosh, who is both a skillful chemist' and a 

A brief preliminary statement of his observations appears from the pen of Mr. Mackintosh (now of Lehigh 
University, Bethlehem, Pennsylvania) in the School of Mines Quarterly for July, 1886, p. 364. 
