Scheerer on Isomorphism. 59 
(R) =41 ‘9 Mg, 3-0 Fe, 136 HY, and in addition, O04 Al. The 
lustrous asbestus from Reichenstein has a similar composition, ac- 
cording to von Kobe as has also the Baltimorite, according to 
Thomson. The oxygen ratio of the former is 22: 4 : 20: 04, and 
that of the latter, 20°57 ; 19-45. 
6. Chloropheite. (Forchhammer.) 
17-07 : 17-24. (R)? Si. 
(R) = 3-44 Mg, 21:56 Fe, 42°15 Bt. 
All these minerals, whose amount of water eps from 5-80 
to 42°15 per cent., have therefore the same form 
and in a chemical point of view, are only distinet therefrom in 
consequence of the different but isomorphous composition of the __ 
member (R). Of these minerals, there is as yet but one that has 
been met with distinctly crystallized—this i is villarsite. Its crys- 
ine form belongs, like that of serpentine, to the rhombic sys- 
tem, but the prism of villarsite has angles of 120°, whereas those 
of serpentine are 130°. The macrodiagonals of both prisms are 
therefore as tan 65° : tan 60° = 2-144 ; 1-732, or very nearly = 
5:4. The fotm of villarsite therefore, may ‘be supposed to be 
one derived from that of serpentine 
7. Picrophyll. ( on ) 
Obtained, 25°87 : 16°35 R): & 
Required, 25-00 : 16: eet" (R)* Si. 
(R) = 30:10 Mg, 6°86 Fe, 0:87 Ca, a trace of Mn, 9:83 H, be- — = : 
sides 1:11.Al. Deducting this latter asa } silicate, the oxygen 
ratio becomes = 25:52 : 16°35, very nearly therefore as 3:2, 
The analysis gave 1°52 per cent. loss. 
8. Aphrodite. (Berlin.) 
17-11 Sets 
26 7 17:86 : (R)? Si. 
(R) from two analyses = 33-72-34-07 Mg, 1-62-1-49 Mn, 0°59 
Ze, 55 Fe, 12: 32-11 34 H, besides 0:20-0:13 Al. 
9. Spadaite. (v. Kobell.) 
29-09 ; 15:38 
29:09 : 14-55 : (R)? Si*. 
(R.) = 30:67 Mg, 0:66 Fe, 11:34 H, 0:66 Al, 0-67 loss. 
10. Picrosmine. (Magnus. ) 
28°39 :.15°16 a 
30-00 : 15-00 (R)? Si", 
"For the facility of com ha b all "4 follow g minerals give 
tne oxygen ratio pape tg octal formal, below i" ac: gets the 
ysis 
