Vol.  49-] 
GEANITE  EX'  “HZ  GABBBO  OF  IHZ  CTILLIZ  KILLS. 
x  t  i 
the  fused  mass,  which  was  observed  by  him  in  the  walls  of  a  disused 
limekiln.1 2 3  Mr.  Eutley’s  investigations  upon  various  rocks  which 
had  been  submitted  to  the  action  of  heat  in  a  glass-furnace  for 
considerable  periods  of  time.”  and  Doelter  and  Hussak’s  researches 
on  the  action  of  molten  magmas  on  various  minerals/  also  throw 
light  upon  some  of  the  questions  raised  by  the  study  of  rock- 
inclusions  in  liquid  lavas ;  nor  are  the  well-known  observations 
of  Sir  -James  Hail.  Gregory  "Watt.  Sorby,  Waller,  and  manv  others 
who  have  experimented  on  the  fusion  of  rocks,  without  bearing  on 
these  enquiries. 
These  observations  have  made  tolerably  familiar  to  geologists  the 
nature  of  the  changes  which  are  induced  in  the  several  minerals  of 
rocks,  when  they  are  exposed  to  a  temperature  sufficiently  high  to 
produce  partial  fusion  :  they  have  at  the  same  time  shown  how 
frequently  spherulitie  structures  are  developed  in  the  groundmass  of 
rocks  placed  under  such  conditions,  and  caused  to  soften  if  not 
actually  to  fuse. 
Tae  interesting  question  of  the  changes  produced  in  igneous  rocks 
that  have  been  subjected  to  partial  re-fusion  has  also  been  discussed 
in  some  other  memoirs  to  which  I  must  call  especial  attention, 
seeing  that  the  phenomena  described  have  a  very  close  analogy 
indeed  with  those  that  are  considered  in  the  present  paper.  In 
1877  Prof.  Bonney  showed  that,  at  two  points  in  the  Island  of 
Arran,  a  remarkable  spherulitie  structure  has  been  developed  in 
acid  rocks  (quartz-felsites  where  they  are  in  contact  with  other 
igneous  masses  that  have  been  intruded  into  them.4  On  the 
Corriegills  shore  this  effect  has  been  produced  by  the  intrusion  of 
a  mass  of  pitebstone  :  while  north  of  Drumadoon  the  agent  of 
alteration  is  a  basic  protrusion.  At  both  localities  I  have  been  able 
to  verify  the  very  interesting  observations  of  Prof.  Bonney. 
2.  The  Pkoducts  of  ihe  Bz-rrsiox  of  Qitabiz-Felsiiz  Fba&hehts 
BY  IHE  BaSALI  OP  ASCHEEHUBEL.  SaXOST.. 
The  geologists  of  Saxony  have  long  been  acquainted  with  a  remark¬ 
able  case  of  the  enclosure  of  fragments  of  an  acid  rock  in  one  of 
basic  composition,  and  the  results  in  that  case  are  so  similar  to  those 
here  described  from  the  Western  Isles  of  Scotland  that  I  must  refer 
to  it  at  somewhat  greater  length :  more  especially  is  this  necessary 
as  the  details  which  enable  us  to  make  the  comparison  nave  only 
very  recently  been  laid  before  the  scientiric  world. 
Wore  than  twenty  years  ago,  when  visiting  Freiberg,  I  obtained 
1  :  Timgescbmolzene  Basal te  und  Granite  von  Edersgrbii  bei  Earlsbadf 
Verh.  d.  k.  k.  Beiehsanst.  1880.  p.  314. 
2  *  Notes  on  the  Alteration,  induced  by  Heat  in  certain  Titreous  Boevs,  based 
on  experiments  of  Douglas  Herman  and  &.  F.  Bodwell,’  Proc.  Boy.  roe. 
\ol.  xl.  (1886)  pp.  430 — 441. 
3  •  Ueber  die  Einwirkung  gesehmolzener  Magma  auf  verschiedene  Mine- 
ralien,’  Xeues  Jahrb.  1884.  voL  i.  pp.  Is— 44. 
4  Geol.  Mag.  for  187 7.  pp.  50 5-509. 
Q.J.G.S.  ffo.194.  *  * 
