Water Analysis: a Practical Treatise on the Examination of Potable Water

Abstract

IN the preface to this edition we are told that the whole of the last edition has been transferred almost without alteration, but with slightly different arrangement; and that some new matter has been added, consisting of the tetration of waters; a modification of the process for estimating nitrates; a chapter on volatile organic matter; a method of estimating minute traces of lead; and a chapter on the purification of waters. The tetration of waters is the estimation by standard solutions of the amount of acid present in waters contaminated by the refuse of certain factories or in rain water which has fallen near alkali works. We had thought that the word tetration, in the preface, was a misprint for litration until we found it so spelt in the text; the latter word (or modification), however, appears on p. 38. The modification of the process for the estimation of nitrates consists in treating the water to which caustic soda has been added with a large excess of aluminium scraps, and pouring off the liquid before distillation, instead of permitting all the aluminium to be dissolved, as in Mr. Chapman's original modification of Schulze's process. In the chapter on volatile organic matter, it is pointed out that on distillation of a water with potassic hydrate, there passes over, together with the ammonia, some combined nitrogen, probably in the form of organic bases, and a process is described for its estimation. The method of estimating minute traces of lead by comparison of the coloration produced by sulphuretted hydrogen water in dilute standard solutions of lead with that obtained by the same reagent in the water under examination is not new, for we remember having seen the experiment illustrated in Dr. Hofmann's lectures at least fifteen years ago. The previous removal of oxidising agents by sulphurous acid is, nevertheless, a useful addition. In the chapter on the purification of water, an ingenious experiment is described to show that separation of suspended matter by filtration through sand and similar substances is really due to subsidence within the interstices of the filter.

Water Analysis: a Practical Treatise on the Examination of Potable Water.

By J. Alfred Wanklyn E. T. Chapman. Second Edition, edited by E. T. Chapman, Member of the Council of the Chemical Society. Pp. 108. (London, 1870.)