and different results as regards carbonic acid and bicarbonates would probably be obtained. Both these would convert the lime in the hide into chalk, which is both insoluble and inert, and the hide would probably fall, at any rate till the lime was completely carbonated, while hides would remain plumpest in waters most free from substances capable of neutralising lime. One of the waters most effective in plumping limed hides is that of the river at Lincoln. Its hardness and contents in chlorine is, as compared with Lowlights water in dry weather, Per 100,000. _Lincoln_, permanent hardness 8·43, temporary 8·32, chlorine 2·60 pt. _Lowlights_, " " 60·5, " 45·0 " 41·7 " Both waters have a considerable quantity of organic matter, and both owe their hardness in part to magnesia. From this we might conclude, what may be _à priori_ expected, that the softer the water, the plumper limed hides remain in it. I am informed, however, by Mr. S. L. Evans, that in the Dartmoor water, which is very soft, but peaty, hides fall rapidly. In this case the colouring matters of the peat, which are of the nature of very weak acids, probably neutralise the lime. It may also be remarked, that wherever the conditions of putrefaction or decaying organic matter is present, hides rapidly fall, for the same reasons as they do in a bate. While the injurious effect of bicarbonates on limed hide is matter of common experience, their influence on liquors and tanning is not so well understood. It is certain that they neutralise and combine with the organic acids of the liquors, and probably with some species of tannin, and as 1 part per 100,000 amounts to 1 oz. per 100 cub. ft., the acid required to neutralise a very hard water amounts to something considerable. It is well known that hard waters make bad tea, and the influence of hardness on the extraction of tannin is a subject well worthy of investigation, and which the writer hopes to examine. On dyeing, at least as regards dye-woods, the influence of bicarbonates is distinctly favourable, and this is also stated to be true of woad, cochineal, and indigo-carmine.