594 
Street  Dust. 
f  Am.  Jour.  Pharm. 
j      Dec,  1877 
This  dust  was  of  a  deep  black  color.  On  ignition,  combustible 
hydrocarbons — bitumen — originating  from  coal,  were  liberated,  of  which 
said  dust  coniained  at  least  from  30  to  35  per  cent.  Previous  to 
analysis  the  dust  was  sifted  through  a  moderately  fine  sieve. 
As  to  the  estimation  of  glutin  I  used  the  following  method  :  I  GO 
grams  of  dust  were  extracted  with  strong  boiling  alcohol,  to  which  a 
few  drops  of  caustic  soda  solution  had  been  added  to  render  it  slightly 
alkaline.  The  dust  thus  extracted  was  then  dried  on  a  water-bath  to 
expel  the  alcohol,  and  boiled  with  500  cc.  of  distilled  water.  The 
alcoholic  extract  contained  a  brown  coloring  matter,  and  decomposed 
organic  substances  in  small  quantity,  for  the  extraction  of  which  I  had 
applied  this  treatment  with  hot  slightly  alkaline  alcohol.  The  subse- 
quent aqueous  extract  contained  dissolved  glutin,  which  was  weighed 
after  evaporation  to  dryness  on  a  water-bath.  It  was  finally  ignited, 
and  the  weight  of  the  ashes  deducted  from  the  one  previously  obtained. 
In  the  following  analyses  the  treatment  of  dust  with  alcohol  was 
omitted  ;  the  glue  was  estimated  on  evaporation  of  the  aqueous  extract 
to  dryness  in  a  tared  platinum  dish,  and  deduction  of  the  ashes  on  sub- 
sequent ignition. 
1. 
2. 
3* 
4. 
5- 
Moisture, 
0-927 
0-725 
1-512 
1-534  per  cent 
Volatile  organic] matter, 
9-928 
5*734 
6*i  52 
2-492 
3"*43 
Fixed  carbon, 
6-847 
10*295 
13*874 
7-524 
20*108 
Ash, 
82-253 
82*792 
79-249 
88-472 
75  215 
ioo* 
ioo- 
IOO' 
IOO" 
IOO* 
Iron, 
6-84 
9-69 
741 
5-130 
571 
Glue, 
6-214 
0-602 
1-272 
3521 
4731 
No.  1  was  dust  from  the  horse-track  on  Penn  street,  near  Union 
Depot,  and  was  of  a  grey  color.  No.  2  was  from  Smallman  and  31st 
streets,  and  also  contained  coal,  recognizable  by  the  liberation  of  com- 
bustible hydrocarbons — bitumen — on  heating.1  No.  3  was  taken  from 
main  road  of  Black  Diamond  Steel  Works,  and  was  of  a  dark-grey 
color  and  contained  coal.  No.  4  was  dust  from  32d  and  Liberty  sts., 
free  from  coal,  and  of  a  light-grey  color.  No.  5  was  collected  from 
Penn,  between  30th  and  31st  streets.    Some'dust  and  debris  was  taken 
1 1  am  aware  of  the  fact  that  glue,  besides  leaving  a  carbonaceous  residue,  also 
forms  combustible  gases  on  ignition,  requiring,  however,  a  higher  temperature  than 
necessary  for  the  liberation  of  bitumen  from  coal. 
