256 REPORT—1899, 
the results be expressed as parts of nitrogen over 100,000, including the 
ammonia expelled on boiling with alkaline permanganate, which should 
be termed albuminoid nitrogen. The nitrogen will, therefore, be re- 
turned as— 
(1) Ammoniacal nitrogen from free and saline ammonia, 
(2) Nitrous nitrogen from nitrites. 
(3) Nitric nitrogen from nitrates. 
(4) Organic nitrogen (either by Kjeldahl or by combustion, but the 
process used should be stated). 
(5) Albuminoid nitrogen. 
The total nitrogen of all kinds will be the sum of the first four deter- 
minations. 
The Committee are of opinion that the percentage of nitrogen oxidised, 
that is, the ratio of (2) and (3) to (1) and (4), gives sometimes a useful 
measure of the stage of purification of a particular sample. The purifica- 
tion effected by a process will be measured by the amount of oxidised 
nitrogen as compared with the total amount of nitrogen existing in the 
crude sewage. 
In raw sewage and in effluents containing suspended matter it is also 
desirable to determine how much of the organic nitrogen is present in the 
suspended matter. 
In sampling, the Committee suggest that the bottles should he filled 
nearly completely with the liquid, only a small air-bubble being allowed _ 
to remain in the neck of the bottle. The time at which a sample is 
drawn, as well as the time at which its analysis is begun, should be noted. 
An effluent should be drawn to correspond as nearly as possible with the 
original sewage, and both it and the sewage should be taken in quantities 
proportional to the rate of flow when that varies (e.g. in the emptying of 
a filter bed). 
In order to avoid the multiplication of analyses the attendant at 
a sewage works (or any other person who draws the samples) might be 
provided with sets of twelve or twenty-four stoppered + Winchester 
bottles, one of which should be filled every hour or every two hours, and 
on the label of each bottle the rate of flow at the time should be written. 
When the bottles reach the laboratory quantities would be taken from each 
proportional to these rates of flow and mixed together, by which means a 
fair average sample for the twenty-four hours would be obtained. 
The Committee at present are unable to suggest a method of reporting 
bacterial results, including incubator tests, which is likely to be accept- 
able to all workers. 
Bibliography of Spectroscopy.—Interim Report of the Committee, con~ 
sisting of Professor H. McLerop, Professor Sir W. C. Roserts- 
AusTEN, Mr. H. G. Mapan, and Mr. D. H. NaGeu. 
Tue collection and verification of titles of papers has been proceeded with, 
and the Committee hope to be able to continue the work untii it can be 
taken up by the compilers of the International Catalogue of Scientific 
Papers. 
The Committee therefore ask for reappointment. 
