470 
Varieties. 
/  Am.  Jour.  Phabm. 
\    Oct.  1, 1871. 
If  no  sediment  remains,  then  only  test  for  lime  as  follows  :  Add 
ammonia  in  excess,  which  precipitates  the  oxide  of  lead,  then  decant 
and  add  a  solution  of  carbonate  of  potassa,  which  precipitates  the 
lime  if  present.  This  is  dried  and  weighed,  and  the  amount  of  car- 
bonate of  lime  it  represents  is  calculated  as  follows  : 
28  :  50  ::  weight  of  precipitate  :  x 
X  =  weight  of  chalk. 
Or  the  solution  may  be  treated  with  oxalate  of  ammonia,  which 
precipitates  the  lime  as  oxalate  of  lime  ;  this  may  be  converted  into 
a  carbonate  by  ignition  and  then  weighed. 
If,  on  the  addition  of  diluted  nitric  acid,  an  insoluble  residue  is 
left,  then  this  residue  must  be  tested  for  the  sulphates  of  baryta, 
of  lead  or  of  lime.  Boil  the  residue  with  dilute  hydrochloric  acid  ; 
the  sulphates  of  lead  and  of  lime  will  be  dissolved  and  the  baryta  left ; 
this  may  then  be  dried  and  weighed.  Precipitate  the  lead  by  adding 
ammonia  and  sulphide  of  ammonium,  the  sulphide  of  lead  formed  is 
treated  with  concentrated  nitric  acid,  which  converts  it  entirely  into 
sulphate,  and  as  such  it  may  be  weighed  and  directly  determined. 
Lastly,  the  lime  may  be  precipitated  by  oxalate  of  ammonia,  ignited 
and  converted  into  carbonate  of  lime,  this  is  dried  and  weighed,  and 
the  amount  of  sulphate  of  lime  it  represents  is  calculated  as  follows ; 
50  :  68  ;:  weight  of  ignited  oxalate  of  lime  :  x 
X  =  weight  of  sulphate  of  lime. 
— Leavenworth  Jour.  Fhar.,  August,  1871. 
Sassafras  Oil. — The  manufacture  of  sassafras  oil  has  been  conducted  for  the 
past  two  years  in  Kichmond,  Ya.,  on  an  extensive  scale.  The  oil  manufactured 
amounts  to  two  per  cent,  of  the  stock  used,  800  pounds  of  unrectified  oil  bein^ 
made  from  40,000  pounds  of  the  root.  This  quantity  is  further  reduced  by 
rectification  and  cleansing  from  sediment  and  impurity.  A  gallon  of  the  fine 
oil  weighs  10  pounds,  and  about  40  gallons  are  produced  every  week.  The 
root  is  first  cut  up  fine  by  a  chopping  machine,  and  the  raw  materials  are  placed 
in  a  large  tub,  which  is  closed,  and  steam  is  then  forced  through  the  mass.  The 
oil  is  then  distilled  by  the  ordinary  process.  It  is  largely  used  for  scenting 
toilet  soap,  and  for  flavoring  tobacco. — Med.  and  Surg.  Rep.i  Aug.  26,  1871. 
The  Preservation  of  Pepsin. — Dr.  Lionel  Beale  writes  to  Nature  to  the  efi'ect 
that  the  means  hitherto  adopted  for  preparing  pepsin  for  medical  purposes  are 
