Am.  Jour.  Pharm. 
Jan.,  1893. 
Proteids. 
39 
varieties  of  albumin.  Serum  albumin  is  not  coagulated  by  ether, 
egg  albumin  is. 
Muscle  and  milk  also  contain  albumins. 
Vegetable  Albumin. 
Class  2,  Globulins. — Insoluble  in  water,  soluble  in  dilute  but 
insoluble  in  saturated  saline  solutions.  Coagulated  by  heat.  The 
following  are  examples  : 
Fibrinogen. — A  proteid  contained  in  blood  which  coagulates  when 
blood  is  removed  from  the  body,  giving  rise  to  the  familiar  blood- 
clot,  i 
Vitellin. — The  chief  proteid  constituent  of  yolk  of  egg. 
Myosin. — The  chief  proteid  of  lean  meat  or  dead  muscle. 
Serum  Globulin. 
Vegetable  Globulins. — Vegetable  proteids  are  chiefly  membersjof 
this  group.  The  aleurone  grains  of  castor  oil  seeds  contain  a  glob- 
ulin in  a  crystalline  form.  Jequirity  seeds  contain  two  proteids,  one 
of  which  is  a  globulin.  Both  of  them  are  intensely  poisonous  when 
subcutaneously  injected,  although  apparently  harmless  when  taken 
by  the  mouth. 
Snake  Poison  also  contains  a  globulin. 
Globin. — Haemoglobin,  the  coloring  matter  of  blood,  is  composed 
of  haematin  (a  pigment  matter  containing  iron)  and  a  globulin  called 
globin. 
Class  j,  Derived  Albumins  or  Albuminates. — These  are  insoluble 
in  pure  water  or  saline  solutions,  but  soluble  in  dilute  acids  and 
alkalies.  Their  solutions  are  not  coagulated  by  heat.  They  are 
called  "derived  albumins,"  because  they  are  derived  from  albumins 
or  globulins  by  the  action  of  acids  or  alkalies,  (a)  Acid-albumin. 
By  warming  a  dilute  solution  of  egg  albumin  with  dilute  sulphuric 
acid  the  solution  loses  its  property  of  coagulating  when  heated.  It 
contains  acid-albumin.  By  exactly  neutralizing  the  solution  with 
dilute  solution  of  sodium  hydrate  a  precipitate  of  acid-albumin  is 
obtained.  Excess  of  alkali  redissolves  this  precipitate  forming  alkali- 
albumin — in  fact,  the  two  are  mutually  convertible,  (b)  Alkali-albu- 
min. This  is  obtained  by  warming  albumin  or  globulin  solutions 
with  alkalies.  By  exactly  neutralizing  the  solution  with  dilute  acid 
alkali-albumin  is  precipitated,  excess  of  acid  converting  it  into  acid- 
albumin. 
Class  ^,  Albumoses. — These  are  soluble  in  distilled  water,  and 
