VARIETIES. 
465 
On  t%e  Composition  of  Yeast  Powder.  By  Edward  N.  Kent. — The  fol- 
lowing analysis  was  instituted  for  the  purpose  of  ascertaining  the  composi- 
tion of  the  yeast-powders  which  are  now  extensively  sold  by  grocers. 
Mixed  with  water,  effervescence  is  produced  by  liberation  of  carbonic  acid. 
A  portion  remains  undissolved  by  cold  water,  which,  when  heated,  forms  a 
clear  gelatinous  mass,  which  becomes  blue  with  the  iodine  test,  starch. 
The  portion  soluble  in  cold  water  gives  precipitates  with  salts  of  lime,  cha- 
racteristic of  tartaric  acid  ;  and  with  chloride  of  platina  gives  potash.  A 
portion  of  the  original  powder  heated  to  redness,  and  treated  with  burning 
alcohol,  gives  yellow  and  violet  flame,  including  soda  and  potash. 
A  quantitative  analysis  of  the  yeast  powder  gave  the  following  results : 
A  portion  treated  with  water,  and  the  gas  dried  by  chloride  of  calcium, 
gave  *085  carbonic  acid. 
A  separate  portion  ignited,  the  residue  treated  with  hydrochloric  acid, 
and  the  alkaline  chlorides  thus  formed  separated  by  the  double  chloride  of 
platina  and  sodium  gave  vt37  potash,  and  *096  soda. 
Another  portion  treated  with  cold  water  gave  -227  starch. 
The  tartaric  acid  and  water  estimated  as  loss  gave  455.  By  calculation 
as  cream  of  tartar,  this  leaves  -045  water  in  combination  with  the  soda. 
The  carbonic  acid  formed,  is  in  larger  proportion  to  the  soda  than  exists 
in  the  neutral  carbonate,  and  in  less  proportion  than  exists  in  the  bicarbon- 
ate, from  which  I  infer  that  an  intermediate  carbonate,  which  is  sold  under 
the  name  of  soda-salceratus,  is  used  for  the  preparation  of  yeast-powder. 
The  per  centage  composition  of  the  powder  is : 
Carbonic  acid  «085  \ 
Soda  -096  (  =22-6,  Soda-salseratus. 
Water  -045  ) 
Potash  -137  )  _ 
Tartaric  acid  and  water  .    -410  J  ~ 54'7  cream  of  tartar' 
Starch  -227        22-7  starch. 
1.000  100. 
Synthesis. — Crystallized  bitartrate  of  potash,  powdered  and  sifted,  is 
better  than  the  same  article  which  is  sold  in  an  impalpable  powder,  as 
cream  of  tartar,  the  latter  being  too  fine,  and  consequently  the  gas  is  libe- 
rated too  rapidly  when  mixed  with  water.  Corn  starch  is  more  palatable 
than  that  from  wheat,  and  consequently  is  the  best.  These  articles  mixed 
with  soda-salseratus,  in  the  above  proportions,  gives  yeast  powder  identical 
with  the  one  analyzed. — New  York  Journ.  Pharm.,  June,  1853. 
An  Account  of  a  Deep-sea  Sounding  in  7706  fathoms,  in  36°  49'  South 
Latitude,  and  37°  6'  West  Longitude.  By  Captain  Henry  Mangles  Den- 
ham,  R.  N.,  F.  R.  S. — This  sounding  was  obtained  on  a  calm  day,  October 
30,  1852,  in  the  course  of  the  passage  of  H.  M.  ship  Herald,  from  Rio  de 
Janeiro  to  the  Cape  of  Good  Hope.    The  sounding-line  was  l-10th  of  an 
32 
