84 
VARIETIES. 
posited  in  transparent  crystals  of  a  cubical  form,  which,  in  a 
few  days,  form  magnificent  arborescences,  and  shine  with  the 
lustre  and  color  of  the  diamond.  This  state  may  be  preserved 
by  avoiding  the  light,  but  by  the  sunlight,  or  even  by  diffused 
light,  they  pass  to  a  brilliant  garnet-red  color,  and  resemble 
rubies.  A  crop  of  colorless  crystals  may  be  got  upon  the  sur- 
face of  these. — Journal  of  the  Franklin  Institute,  December, 
1866. 
tlaricticB, 
Insects,  fabricators  of  Iron. — It  is  well  known  that  some  insects  are 
skilful  spinners,  but  it  was  not  known  that  some  of  them  fabricated  iron. 
A  Swedish  naturalist,  M.  de  Sjogreen,  has  published  a  curious  memoir  on 
this  subject.  The  insects  in  question  are  almost  microscopic  ;  they  live 
beneath  certain  trees,  especially  in  the  province  of  Smaland,  and  they 
spin,  like  silk-worms,  a  kind  of  ferruginous  cocoons,  which  constitute  the 
mineral  known  under  the  name  of  "  lake  ore,"  and  which  is  composed  of 
from  20  to  60  per  cent,  of  oxide  of  iron  mixed  with  oxide  of  manganese, 
10  per  cent,  of  chloric,  and  some  centimetres  of  phosphoric  acid.  The 
deposits  of  this  mineral  may  be  200  metres  long,  from  5  to  10  metres  wide, 
and  from  8  to  30  inches  thick. — Medical  News,  Nov.,  I860,  from  Rev.  de 
Th&rap.  Med.-  Chintrg.,  Sept.  15,  1866. 
Poisoning  by  Cyanide  of  Potassium  through  carelessness. — Two  cases  of 
this  are  reported  in  a  recent  number  (June  21,  1866]  of  the  Boston  Med. 
and  Surg.  Journal,  which  deserve  public  attention. 
In  the  first,  a  porter  in  a  machine  shop,  being  thirsty,  dipped  a  tin  cup 
into  ajar  of  liquid,  which  he  supposed  to  be  water,  and  swallowed  about 
three  draehms  before  he  discovered  his  mistake.  In  two  minutes  he  be- 
came senseless,  and  was  taken  to  the  hospital,  and,  strange  to  say,  after 
an  emetic,  the  use  of  the  stomach-pump  and  of  ammonia,  he  recovered  ; 
for  the  amount  of  the  poison  swallowed  was  estimated  at  twenty-three 
grains,  and  thirty-five  minutes  elapsed  before  any  of  the  remedies  took 
effect. 
The  other  case  occurred  a  few  days  ago  under  similar  circumstances. 
A  thirsty  man,  a  stranger  amongst  us,  went  into  a  jeweller's  shop,  and 
asked  for  a  drink  of  water.  He  was  directed  to  the  rear,  where  the  sink 
was  situated.  Seeing  a  large  covered  stone  jar  standing  near  it,  such  as 
is  often  used  for  holding  ice-water,  he  lifted  the  cover  and  drank,  without 
stopping  to  look  at  it,  about  half  an  ounce  of  the  liquid.  He  became  in- 
sensible in  five  minutes.    It  was  found  impossible  to  administer  an  emetic 
