336 ON THE DETERMINATION OF ORGANIC MATTER IN WATER. 
form some judgment on this subject by noting in which fractions the ammonia 
came over. Even when urea is present, the first fraction generally contains 
most ammonia, but the decrease is not nearly so rapid as when it is absent. Of 
course when the ammonia present as such in the original water admits of being 
directly estimated before distilling, there is no occasion for this division into 
fractions, and we may at once distil over 300 or 500 c.c., and estimate the am¬ 
monia in this distillate. 
II. The distillation being interrupted, 20 c.c. of a solution containing half 
its weight of caustic potash are added to the contents of the retort, and the dis¬ 
tillation proceeded with. The distillate is, as before, divided into 100 c.c. por¬ 
tions, or preferably collected into one large 300 c.c. portion and submitted to 
Nessler’s test for ammonia. 
III. Crystals of permanganate, about *3 gramme or more, are added in such 
quantity as to render the contents of the retort of a deep violet colour, and the 
distillation is proceeded with. It is sometimes necessary to replenish the retort 
with 100 c.c. or 200 c.c. of pure (i.e. non-ammoniacal) water. 300 c.c. of dis¬ 
tillate are drawn over and divided into two portions, each of which is subject to 
Nessler’s test. 
The second distillate contains less than one-third of the ammonia derived 
from the destruction of the albuminoid substances of the water. A full third 
of the nitrogen of these substances may be obtained by pushing the potash 
treatment to dryness, but in practice this is inconvenient. 
Quantitative Examples .—Water from the Thames, mid-stream at London 
Bridge, tide, two hours’ flood, taken and examined June 18th, 1867. Filtered 
before examination. 
Quantity of ammonia in 1 litre of water — T4 milligramme :—- 
Distillate I.—1st 100 c.c. = 1-40 milligramme NH 3 . 
2nd 100 c.c. = 0-28 ,, „ 
3rd 100 c.c. = 0-08 ,, „ 
4th 100 c.c. = traces. 
5th 100 c.c. = absent. 
Distillate II.—1st 100 c.c. 0-02 milligramme NH 3 . 
2nd 100 c.c. = trace. 
Distillate III.—1st 100 c.c. — 0 - 28 ,, „ 
2nd 100 c.c. = 0-05 „ „ 
w ,, ,, 
Result:—NII 3 existent in the form of urea = 0-36 
,, ,, ,, albuminoid = 0‘35 
which corresponds to 1*27 milligramme of urea, and to 12-6 milligrammes of 
ydiite of egg, as it exists in a fresh egg. 
New River water : — 
Distillate I.—300 c.c. gave '06 milligramme NH 3 . 
„ II.—300 c.c. gave -03 ,, ,, 
,, III.—300 c.c. gave -06 „ „ 
East London water, kept eighteen hours:— 
Distillate I.—300 c.c. gave ’01 
,, II.—300 c.c. gave '01 
,, III.—300 c.c. gave *089 
Such are the results obtained by Professor Wanklyn and his coadjutors. 
Should they stand the test of experiment in the hands of other operators, they 
will represent an important advance upon the methods hitherto in general use. 
They have not, however, been permitted to pass unchallenged. Mr. Dugald 
