AmjJa0nUri876harm'}    Development  of  the  Chemical  Arts.  31 
ammoniacal  solution  of  sulphate  or  chloride  of  nickel,  diluted  with 
water  until  it  appears  colorless.  A  few  drops  of  a  solution  of  sulpho- 
carbonate  will  produce  with  the  reagent  a  very  characteristic  currant 
color  ;  while  liver  of  sulphur,  which  is  occasionally  sold  as  sulphocar- 
bonate,  produces  a  yellow,  and  the  alkaline  monosulphides  a  brown  or 
black  color. — Ibid,,  p.  352. 
Devorative  Capsules. — Under  this  name,  the  chemical  factory  of  Hel- 
fenberg,  near  Dresden,  has  introduced  capsules  which  are  made  of  a 
material  similar  to  sheet  wafers,  but  rolled  out  very  thin  like  vellum 
paper.  It  is  -used  like  ordinary  powder  paper,  except  that  after  the 
powder  has  been  put  upon  it  the  length  margin  is  moistened  with  water 
by  means  of  a  hair  pencil ;  it  is  then  folded  in  the  usual  way,  the  ends 
being  likewise  fastened  by  the  aid  of  moisture.  The  entire  capsule 
with  contents  is  swallowed  after  having  been  dipped  in  water  and,  if 
necessary,  rolled  up. — Phar.  Centr.  Halle,  1875,  No.  42. 
REPORT  ON  THE  DEVELOPMENT   OF   THE   CHEMICAL  ARTS 
DURING  THE  LAST  TEN  YEARS  * 
BY  DR.  A.  W.  HOFMANN. 
(Continued  from  page  559  of  last  volume.) 
Hydrogen. 
Of  the  three  properties  to  which  the  industrial  applications  of  hydrogen  are  appli- 
cable two  are  of  so  striking  a  nature  that  they  cannot  have  escaped  the  earliest 
observers.  To  them  it  appeared  as  the  combustible  principle,  the  "volatile  sul- 
phur ^'f  subsequently,  it  was  regarded  as  the  long-sought-for  phlogiston, %  or  as  the 
"  inflammable  air,"  of  which  all  combustible  gases  were  mere  varieties.  In  modern 
times,  this  previously  vague  knowledge  has  been  rendered  definite,  recognizing  in 
hydrogen  the  greatest  heat  of  combustion,  and  consequently  the  property  of  produc- 
ing the  highest  degrees  of  heat  and  light,  properties  which  met  with  a  practical 
application  at  an  early  date. 
The  low  specific  gravity  of  hydrogen  did  not  escape  the  earliest  observers.  Being 
scarcely  ponderable,  it  excited  the  idea  of  imponderable  bodies,  and  its  specific  light- 
ness, as  well  as  its  great  heat  of  combustion,  soon  met  with  a  striking  application. 
A  third  attribute  is  of  a  less  manifest  nature.    Occasionally  destroying  colors, 
but  often  obtained  without  any  brilliant  and  striking  phenomena,  hydrogen  in  its 
nascent  state  is  capable  of  entering  into  many  combinations,  of  which  it  is  incapable 
when  pre-existing  in  a  free  state.    It  liberates  chlorine,  oxygen,  and  other  elements 
from  their  compounds,  and  takes  their  place  j  or  it  is  deposited  in  compounds  not 
fully  saturated,  and  fills  up  the  vacancies.    This  attribute  is  most  weighty  for  the 
*  "  Berichte  fiber  die  Entwickelung  der  Chemischen  Industrie  Wahrend  des  Letzten  J  ahrzeheEds." 
f  Lemery,  "  Memoires  de  l'Academie,"  1700. 
J  Cavendish,  1766. 
