WATER.— Analysis. Organic Carbon and Nitrogen.
973
A.
B.
c.
Total.
Nitrogen.
Difference,.
175-2
27-4
62-4
Add tension of aqueous )
15-5
15-5
15-5
vapour,.. )
190-7
Deduct or add corrcc-")tion for capillarity,.. f
— 0-9
+ 2-2
+ 2-2
189-8
45-1
80-1
Deduct these numbers')
from height of bar- >-
763-0
763-0
763-0
ometer,. \
189-8
45-1
80-1
Tension of dry gas,.
573-2
717-9
682-9
Log. of volume of gas,..
0-83954
1-93699
1-93699
,, 00012562
6-19031
6-19031
6-19031
(1 + 0-00367t)760 .
“ tension of dry gas,
2-75831
2-85606
2-83436
“ weight of gas")
3-78816
4-98336
4-96166
0-0061399
0-0009624
0-0009155
A — B — 0-0051775_ 3
-rrlj -0155325Weight of carbon, -00222
Ji + P = 0'°078779 _ 0 . 00094 _ weig ht 0 f nitrogen. .
In order to correct for the unavoidable impuritiesof reagents and contamination acquired in trans-ferring from one vessel to another, and duringevaporation, &c., each operator should make severalblank experiments to ascertain the “personal errorof himself and his laboratory. In these a litre ofpurified distilled water should be evaporated withthe usual quantities of sulphurous acid and ferrouschloride, with the addition of about 0-1 gram, offreshly ignited sodic chloride, this last being intendedto give bulk to the residue, and thus facilitate itsremoval from the dish. The combustion and gasanalysis should be made as usual, and the averageamounts of carbon and nitrogen thus ascertaineddeducted from the results of all analyses. Thiscorrection, which will be found to be very constant,will amount, perhaps, to about 0-0001 gram, of car-bon, and 0-001105 gram, of nitrogen.
Although the loss of ammonia during evaporationis extremely small, still, when the amount present islarge, it is necessary to apply a correction for thisloss, which appears to be very constant, as shown inTable III. The amount of nitrogen correspondingto the quantity of ammonia present in the watershould be added to the quantity of nitrogen foundby combustion. The quantities in the Table referto parts per 100,000. In the analysis of sewage,where metaphosphoric acid has been used, the cor-rection should be taken from Table IY.
TABLE HI.— PARTS IN 100,000. LOSS OF NITROGEN BYEVAPORATION OF NIL, WITH SULPHIJROL'S ACID.
nh 3
Loss ofN.
nh 3
Loss ofN.
nh 3
Loss ofN.
Loss of
N.
NH3
Loss ofN.
6-0
1-727
4-6
1-372
3-2
•819
1-8
•321
■4
•062
5-9
1-707
4*5
1-332
3-1
•779
1-7
•309
'3
•047
5-8
1-688
4-4
1-293
3-0
•740
1-6
•297
•2
•032
5-7
1*668
4*3
1*253
2*9
•700
1-5
•285
T
•017
5-6
1-648
4'2
1-214
2*8
*661
1-4
•274
•09
■014
5'5
1-628
4*1
1-174
2*7
*621
1*3
*262
•08
•013
5-4
1-609
4-0
1-135
2-6
•582
12
•250
•07
•012
5-3
1-589
3-9
1 -095
2-5
•542
IT
•238
*06
•010
5-2
1-569
3-8
1-056
2*4
•503
1-0
*226
•05
•009
5-1
1-549
3-7
1-016
2-3
•463
•9
•196
•04
■007
5-0
1-530
3-6
*977
2*2
•424
•8
■166
•03
•006
4-9
1-490
3-5
•937
2-1
•384
•7
T36
•02
*004
4-8
1-451
3-4
•898
2-0
•345
•6
•106
■01
•003
4-7
1-411
3-3
•858
1-9
■333
•5
■077
•009
•001
TABLE IV. — LOSS OP NITROGEN BY EVAPORATION OF NIL,WITH METAPHOSPHORIC ACID.
Volume
evaporated.
d
n o
w§
& £p<
!
Loss of N.per 100,000.
Volume
evaporated.
nh 3
per 100,000.
: Loss of N.
1 per 100,000.
Volume
evaporated.
NHg
per 100,000.
Loss of N.
per 100,000.
C.C.
C.C.
c. 0 .
100
10-0
■483
100
6-3
•354
100
2-6
•195
100
9-9
•480
100
6-2
•351
100
2-5
■190
100
9-8
•476
100
61
•348
100
2*4
T84
100
9-7
•473
100
6-0
■345
100
2-3
•179
100
9-6
•469
100
5-9
•341
100
2'2
•174
100
9-5
■466
100
5'8
*337
100
2T
T69
100
9-4
•462
100
5-7
•333
100
2-0
TG4
100
9*3
•459
100
5-6
*330
100
1-9
T58
100
9*2
•455
100
5-5
•326
100
1-8
■153
100
91
*452
100
5-4
*322
ioo
1-7
T48
100
9-0
■448
100
5-3
•318
100
1-6
*143
100
8-9
•445
100
5-2
*314
100
1-5
*137
100
8-8
■441
100
51
•310
100
1-4
*132
100
8-7
•438
100
5*0
•306
100
1*3
T27
100
8-6
•434
100
4-9
•302
100
1-2
T22
100
8-5
•431
100
4-8
•298
100
l'l
■117
100
8'4
•428
100
4-7
■294
100
1-0
•112
100
8-3
■424
100
46
•291
250
0'9
•096
100
8-2
•421
100
4'5
•287
250
0-8
•080
100
8-1
•417
100
4-4
•283
250
0*7
■070
100
8-0
*414
100
4-3
•279
250
0*6
•060
100
7*9
*410
100
4-2
•275
500
0*5
•050
100
7-8
■407
100
41
•271
500
0*4
•040
100
7-7
•403
100
4*0
■267
500
0*3
•030
100
7-6
•400
100
3-9
•262
1000
0'2
•020
100
7-5
•396
100
3"8
•257
1000
0T
*010
100
7'4
•393
100
3*7
•252
1000
0-09
•009
100
7*3
•389
100
3-6
•247
1000
0'08
■008
100
7-2
•386
100
3-5
•242
1000
0'07
•007
100
7*1
■382
100
3-4
•236
1000
0-06
•006
100
7-0
■379
100
3-3
•231
1000
0-05
*005
100
6‘9
■375
100
3-2
•226
1000
0*04
*004
100
6-8
*372
100
31
•221
1000
0*03
•003
100
6-7
•368
100
3'0
•216
1000
0-02
■002
100
6-6
•365
100
2*9
•211
1000
o-oi
•001
100
6-5
•361
10.0
2-8
•205
100
6-4
*358
100
2*7
•200
The nitrogen thus obtained includes that pre-sent in the water as a constituent of organicmatter (organic nitrogen), and that in the form ofammonia. The latter, the determination of whichwill next be considered, being deducted, the re-mainder is the amount of the organic nitrogen inthe water.
To the organic carbon and nitrogen we must lookto form an opinion on the character of the sample,as regards actual organic contamination. It is not