522 
ON  HYDRAULIC  LIMES,  ETC. 
This  thiosinnamine  agrees  in  composition,  properties,  and  crys 
talline  form  with  that  obtained  from  the  natural  essence. 
This  origin  of  essence  of  mustard  from  iodized  propylene,  a 
derivative  of  glycerine,  shows  that  essence  of  garlic  may  be  de- 
rived from  propylene,  C6  H6,  one  of  the  carburets  corresponding 
with  the  alcohols  ;  essence  of  garlic  is  sulphuretted  propylene, 
and  essence  of  mustard  is  sulphocyanide  of  sulphopropylene. 
This  result  will  no  doubt  lead  to  the  production  of  similar  com- 
pounds from  other  carburets  homologous  with  propylene,  especially 
from  olefiant  gas;  and  the  authors  intend  making  some  experi- 
ments in  this  direction. 
They  add,  that  from  the  relation  between  glycerine  and  essence 
of  mustard  established  by  their  experiments,  it  appears  that' the 
latter  may  be  formed  by  means  of  the  neutral  fatty  substances, 
which  are  so  abundant  in  vegetables,  and  especially  in  the 
Cruciferse  ;  this  will  probably  throw  some  light  upon  the  origin 
of  the  natural  essence. — Ghem.  Gaz.9  from  Comptes  Mendus, 
July  2,  1855,  p.  21. 
ON  HYDRAULIC  LIMES,  ARTIFICIAL  STONES,  AND  VARIOUS 
NEW  APPLICATIONS  OF  THE  SOLUBLE  ALKALINE  SILI- 
CATES. 
By  F.  Kuhlmann. 
Theory  of  Hydraulic  Limes  The  author  commences  by  ob- 
serving, that  all  limes,  and  especially  hydraulic  limes  and  natu- 
ral cements,  contain  considerable  quantities  of  potash  and  soda. 
In  a  memoir  read  before  the  Academy  of  Sciences  on  the  4th  of 
May,  1841,  he  considered  that  these  alkalies  served  to  transfer 
silica  to  the  lime,  so  as  to  form  silicates,  which,  when  in  contact 
with  water,  solidify  a  part  of  this  body  by  a  process  of  hydra- 
tation  analogous  to  that  of  plaster.  In  support  of  this  theory, 
he  instances  the  immediate  transformation  of  common  lime  into 
hydraulic  lime  by  simple  contact  with  a  solution  of  silicate  of 
potash.  If,  during  the  burning  of  a  limestone,  potash  is  in  con- 
tact with  silica,  the  silicate  formed  must  necessarily  react,  if  on- 
ly at  the  moment  when  the  burnt  lime  is  brought  in  contact  with 
water. 
Further  experiments  have  proved,  that  by  mixing  common 
