VARIETIES. 
459 
content  with  the  former  method,  of  conveying  plants  in  a  passive  condition, 
closely  packed  in  peat-moss, — a  plan,  however,  which  is  only  partially  suc- 
cessful in  protracted  voyages.  Two  additional  and  highly  interesting  chap- 
ters treat  of  the  application  of  the  "  closed  "  plan  in  improving  the  condition 
of  the  poor  ;  and  on  its  probable  future  applications  in  comparative  re- 
searches in  vegetable  physiology,  and  even  in  the  treatment  of  diseases.  To 
these,  as  to  the  other  topics  of  this  work,  no  justice  can  be  rendered  to  our 
author's  suggestions  except  by  lengthened  quotations,  which  the  nature  of 
this  notice  does  not  admit  of.  It  must  suffice  to  direct  attention  to  this  fas- 
cinating little  volume.  Those  who  read  it  and  who  have  a  true  fondness 
for  growing  plants,  will  scarcely  be  contented  without  a  Ward  case,  of  more 
or  less  pretension,  which  they  will  find  an  unfailing  source  of  interest, 
especially  during  the  long  and  total  suspension  of  vegetation  in  our  pro- 
tracted winters.  With  proper  management,  and  with  the  requisite  amount 
of  light,  any  plant  may  thus  be  cultivated.  But  we  particularly  recommend 
Ferns  and  Lycopodia,  of  the  most  delicate  kinds,  as  requiring  least  care, 
and  as  making  the  prettiest  appearance  at  all  seasons.  Most  of  these  re- 
quire little  light ;  although  our  clear  skies  afford  us  this  in  abundance.  So 
little  bituminous  coal  is  consumed,  even  in  our  largest  cities,  that  the  "fuli- 
ginous matter  "  with  which  all  British  towns  are  begrimmed  and  rendered 
noxious  to  vegetation,  here  interposes  no  obstacle  to  rearing  plants.  Quite 
unlike  England,  the  principle  obstacle  to  the  growth  of  delicate  plants  in 
our  houses  in  winter,  and  in  our  grounds  in  summer,  comes  from  the  dry- 
ness of  the  air.  For  this,  the  Ward  case  affords  a  perfect  remedy  ;  as  no- 
thing is  easier  than  to  furnish  a  saturated  atmosphere  for  those  plants  that 
require  it,  or  to  supply  and  retain  the  degree  of  moisture  which  suits  any 
particular  species. — a.  g. — SilUman's  Journal,  July,  1853. 
Method  of  obtaining  positive  Photographic  Impressions  directly  upon  Plates 
of  any  description,  especially  on  those  intended  for  Engraving.  By  A.  Mar- 
tin.— The  method  employed  by  the  author  is  the  same  as  that  which  he 
described  for  taking  positive  pictures  on  glass.  The  metallic  plate,  covered 
in  the  usual  manner  (but  upon  both  sides)  with  etching-ground,  is  first 
coated  with  [iodized  collodion,  then  dipped  in  the  solution  of  nitrate 
of  silver,  &c.  The  picture,  when  taken,  is  freed  from  the  unmodi- 
fied iodide  of  silver  by  the  bath  of  cyanide  of  silver,  washed  with  water, 
immersed  in  a  solution  of  dextrine,  and  dried.  The  engraver  may  then 
make  the  same  use  of  the  design  that  he  does  of  the  outline,  which  is 
usually  transferred  to  the  etching-ground.  A  second  impression  on  glass 
will  preserve  the  design,  which  the  operation  of  engraving  will  destroy 
upon  the  plate. 
Impressions  taken  in  this  way  upon  varnished  metallic  plates  of  any  kind, 
or  even  upon  cardboard,  unite  with  the  qualities  of  positive  impressions 
upon  glass,  a  strength  and  facility  of  transport  of  which  the  latter  are  defi- 
cient. The  method  is  also  applicable  to  wood  blocks. —  Chemical  Gazette, 
from  Comptes  Bendus,  April  18,  1853. 
