A  NEW  HEMOSTATIC. 
269 
gun-cotton,  which  would  also  in  all  probability  be  found  to 
possess  the  same  property. 
Inclosed  please  find  some  of  the  paper  for  trial.    It  was 
prepared  by  my  son,  M.  M.  Johnston. 
Perhaps  you  will  think  the  matter  of  sufficient  importance  to 
make  a  note  of  it  in  the  Journal  of  Science. 
Respectfully  yours,         John  Johnston. 
I  have  repeated  and  confirmed  Prof.  Johnston's  experiment, 
extending  it  to  gun-cotton.     I  find,  as  he  suggests,  that  the 
latter  substance   produces  the  same  excitement  of  positive 
electricity  which  is  produced  by  the  pyroxiline-paper.  The 
most   energetic  effects  are  produced  when  vulcanized  india 
rubber  is  the  electric.    The  opposite  effects  in  this  substance 
produced  by  flannel  and  the  gun  cotton  or  pyroxiline-paper  are 
very  striking,  and  will  form  a  good  lecture  room  illustration. 
These  substances  also  produce  powerful  positive  excitement  in 
glass.    It  is  difficult  from  the  use  of  pith  balls  alone  to  determine 
which  produces  the  most  powerful  excitement,  glass  or  hard 
rubber,  when  excited  by  gun-cotton  or  pyroxiline-paper.  This 
seeming  anomaly,  confounding  our  ordinary  means  of  discrimi- 
nation in  cases  of  electrical  excitement,  demands  further  in- 
vestigation.   It  would  appear  that  of  negative  electrics  yet 
observed,  these  azotized  species  of  cellulose  are  the  most  re- 
markable— in  comparison  with  which  the  most  highly  negative 
electrics  hitherto  known  become  positive. — Sillimatts  Journal, 
Jan.,  1864.  B.  s.,  JR. 
A  NEW  HEMOSTATIC. 
Dr.  Janssens  has  called  the  attention  of  the  Brussels  Medi- 
cal Society  to  a  new  bcemostatic  proposed  by  Professor  Piazza, 
of  Bologna.  Repeated  experiments  have  shown  him  that  the 
alkaline  chlorides  render  the  clots  formed  by  perchloride  of 
iron  much  more  compact,  more  homogeneous — in  a  word,  more 
fibrinous.  Hence  M.  Piazza  has  conceived  the  idea  of  mixing 
solutions  of  perchloride  of  iron  and  pure  chloride  of  sodium,  as 
in  the  following  formula  :  Pure  chloride  of  sodium,  15  grammes  ; 
neutral  solution  of  perchloride  of  iron  (30  degrees),  2  b grammes; 
distilled  water,  60  grammes.    The  chloride  of  sodium  is  dis~ 
