Referee's report by Robert Warington, on a paper 'A study of the process of nitrification with reference to the purification of sewage' by Miss Harriette Chick Sectional Committee: Botany Not recommended for publication in Philosophical Transactions but the conclusions should appear in Proceedings. The paper contains a large amount of work, carefully and skillfully executed and described in detail. The paper is of undoubted interest but establishes no new facts; almost every result which it carefully proves would probably have been predicted by an expert in the subject. The general conclusions are clearly given and the section describing the chemical investigation is the best. [Published in Proceedings of the Royal Society B, 1906]. Endorsed on verso as received 9 May 1905. 6 May 1905