780 REPORT—1890. 
10. The River Aire: a Study in River Pollution. 
By T. H. Easterriepd, B.A., F.C.S., and J. Mircuett Witson, M.D. 
The paper contained the result of a series of analyses of the water of the River 
Aire, from its source at Malham Cove to its junction with the Ouse above Goole. 
From these results it was shown:—(1) That the river, though a pure stream in its 
upper reaches, becomes more and more polluted as it passes through the townships 
of Gargrave, Skipton, Keighley, Shipley (with Bradford), Kirkstall, and Leeds ; 
(2) That the curves exhibiting the ratio of pollution to mileage from the river source 
showed a series of maxima corresponding to the above centres of population, there 
being a tendency for the river to purify itself, to some slight extent, by natural causes 
when passing through areas in which no sensible amount of pollution was taking 
place; (3) That the Rivers Pollution Acts had been very inefficiently enforced 
in the basin of the River Aire. 
TUESDAY, SEPTEMBER 9. 
The following Reports and Papers were read :— 
1. Provisional Report of the Committee on the Bibliography of Spectroscopy. 
See Reports, p. 261. 
2 Report of the Committee for preparing a new series of Wave-length Tables 
of the Spectra of the EHlements.—See Reports, p. 224. 
3. Report of the Committee on the Absorption-Spectra of Pure Compounds. 
See Reports, p. 339. 
4. On Phosphorous Oxide. By Professor T, E. Toorpz, F.R.S. 
5. Diazoamido-Compounds: a Study in Chemical Isomerism.? 
By Professor RapHanL Mexpora, F.R.S. 
The author gave a résumé of a series of experimental investigations with which 
he had been occupied, in conjunction with Mr. F, W. Streatfeild, for four years, 
and from which it appeared that when the hydrogen atom of mixed diazoamido- 
compounds is replaced by an alkyl radicle, three isomerides are capable of exist- 
ence; whereas the prevailing view of the constitution of these compounds admits 
only of two isomerides. It has been found that the third isomeride can be 
produced in all cases by the combination of two unsymmetrical alkyl-diazoamides. 
Arguing from the view that the power of combination between the two isome- 
rides is due to the unsaturated chain of nitrogen atoms, the author pointed out 
that combination might be expected to occur between two totally distinct un- 
symmetrical compounds. Experiment has justified this conclusion, and two 
cases were described in detail. From these results it follows that the mole- 
cular weight of the mixed diazoamides is double that of the generally-received 
formula. These compounds have been shown by previous investigators, as well 
as by the author, to behave under the influence of most reagents as though 
they contained two isomerides. The present researches tend to prove that this is 
actually the case, the two isomerides constituting the molecule of a mixed diazo- 
amide being held together by the residue of affinity pertaining to the chains of 
1 Published in extenso in Chem. News, vol. 1xii. p. 167, &c. 
2 See Journ. Chem. Soc. Trans. 1890, vol. lvii. p. 785. 
