CHALK-EATING. 
347 
sulphuric  acid,  was  crystalline  from  the  first.  When  precipi- 
tated by  water  from  its  solution  in  alcohol  and  ether,  it  is  doughy 
and  almost  liquid,  and  remains  so  for  a  long  time,  if  there  is  any 
considerable  quantity  of  it. 
The  best  mode  of  preserving  it  appears  to  be  under  water. 
By  standing  thus  it  gradually  hardens,  and  passes  sometimes 
to  a  somewhat  hard  amorphous  mass,  and  sometimes  to  a  granu- 
lar crystalline  state.  It  appears  to  be  wholly  insoluble  in 
water.  A  few  minute  grains  of  the  crystalline  form  diffused 
through  15  or  20  ounces  of  water,  did  not  dissolve  after  many 
hours  standing.  In  a  mixture  of  alcohol  and  ether  it  dissolves 
as  easily  as  sugar  in  water,  and  in  such  quantity  as  to  make 
the  liquid  syrupy. 
Its  detonating  properties  are  but  slight.  If  it  be  well  dried 
and  a  match  applied,  it  deflagrates  with  a  feeble  flash. 
It  has  been  stated  by  Dr  Y.  Monckhover,  that  when  dissolved 
in  alcohol  and  kept  sometime  in  a  warm  place,  it  undergoes  de- 
composition, as  evidenced  by  the  fact  that  the  solution  then  gives 
an  abundant  precipitate  with  nitrate  of  silver,  which  at  first  it 
did  not  do.  An  experiment  made  in  this  direction  did  not  give 
the  result  thus  indicated.  A  solution  of  nitroglucose  in  alco- 
hol, containing  about  40  grains  to  the  ounce,  was  placed  in  a 
stoppered  vial  and  was  kept  in  the  sand  bath  at  a  temperature 
of  about  blood  heat  for  nearly  a  month.  But  neither  it  nor  a 
fresh  solution  gave  a  precipitate  with  alcoholic  solution  of  ni- 
trate of  silver.  It  would  seem  from  this  that  certain  conditions 
of  temperature  or  otherwise  are  necessary,  in  order  that  this 
decomposition  should  take  place. — Am.  Joum.  of  Science  and 
Arts,  May,  1868. 
CHALK -EATING. 
By  W.  W.  Ely. 
Mr.  Editor. — A  gentleman  who  has  been  an  occasional 
patient  of  mine  for  twenty-five  years  past,  began  the  use  of 
chalk  in  1842.  I  have  made  notes  of  the  case,  when  I  have  had 
occasion  to  see  him,  since  April,  1844.  For  some  time  previous 
to  using  the  chalk  he  was  pale  and  sallow,  and  was  affected  with 
