Paesons : Maritime Plants and Tidal Rivers. 117 



and little or none when the converse conditions obtain. On July 

 10th, '1874, a sample taken at the top of a high spring tide at Goole 

 — the season being a very dry one — contained an amount of chloride of 

 sodium corresponding to one part in five, of sea-water. A high spring 

 tide being expected on Oct. 1st, 1875, I made arrangements for the 

 collection of samples at high water, at the various piers and ferries 

 in the neighbourhood. Unfortunately there had been hard rain a day 

 or two before, so that the fresh water coming down from the hilly 

 districts rather interfered with the experiment ; nevertheless the 

 table of the results obtained, on analysis of the samples, shows well 

 the progressive diminution of chlorine and solids in solution from 

 below upwards. (The slight increase at Goole over Swinefleet is 

 probably due to the latter not having been taken exactly at high 

 water.) The proportion of sea- water is calculated from the chlorine, 

 by deducting the quantity (0'75 gr. per gall.) found at Selby— this 

 being the same at low-water- — and comparing the remainder with the 

 amount found in sea-water. The larger quantity found in the Aire 

 at Carlton is due, not to the sea-water, but to the sewage with which 

 that much-abused river has been polluted, as the same quantity is 

 found above -Haddlesey Lock, where the tide does not reach. It 

 appears that a certain proportion of salt reaches as far up the river 

 as New Hay Ferry, near Hemingbrough ; and I am told that at very 

 high tides the water here tastes distinctly salt. At Selby, and for 

 some little distance below, a moss — Cinclidotus fontimloideS'—gYows 

 plentifully on the river bank, which proves that the sea-water does 

 not reach so far as this, for no moss that I am aware of inhabits salt 

 water. 



There is yet another interesting constituent in the river water 

 which it is believed has, at any rate in part, a marine origin : I 

 allude to the " warp," which plays so important a part in the agricul- 

 ture of this neighbourhood. This warp is a fine sediment of a light 

 brown colour, with a peculiar soft, silky feel to the fingers, and 

 containing numerous glistening scales of mica. Mr. Hunter has 

 kindly made for me an analysis of warp from the river Ouse at Goole, 

 from which it will be seen that three-fourths of it consists of sand 

 mica and other matters insoluble in acid, lime and magnesia together 

 constitute about 6 per cent., and alumina rather more than an equal 

 quantity. The composite nature of the warp well explains the 

 character of the flora of this neighbourhood, There are four marked 

 classes of soil, each of which yields to the botanist a peculiar flora, 



