OF WATER FOR ORGANIC MATTER. 65 



other matters. When this was done, I thought it would 

 be interesting to test the Clyde by the new process, and 

 for that purpose obtained specimens at various points, 

 from the Broomielaw to the sea, afterwards continuing 

 till the vessel came near Liverpool. 



^' The column to observe is number i of annexed Table 

 of either series. This gives the amount of oxygen con- 

 sumed instantly, and corresponds, as I believe, to the 

 amount of decomposed matter which has left in solution 

 putrid gases, whatever these gases may be. I shall sup- 

 pose them to be sulphuretted hydrogen in minute quan- 

 tities, or compounds of sulphur, or organic substances 

 only. In the part of the Clyde near Glasgow, all these 

 compounds will probably be found; as we go near the 

 Firth the sulphur will be fully oxidized, and the organic 

 compounds only will be the active agents in taking up 

 the oxygen, as they oxidize more slowly. 



" The amount of oxygen is calculated from the amount 

 of permanganate employed. The method is an extension 

 of the original idea given out by the late Forchammer 

 many years ago; the amount of water used was lOO cubic 

 centimetres or 1544 grains. The permanganate required 

 to give perfectly pure water perceptible colour was in 

 every case subtracted from the number obtained. 



"The examination of the Clyde is not perfect, but 

 there is much to be seen that is interesting. Specimens 

 ought to have been taken higher than any town on the 

 river. They began below Bothwell, or if mile above 

 Cambuslang, about 6| miles above the Quay at Glasgow. 

 We there find the oxygen required for the water to be 

 0*000045 per cent, by weight, or equal to 3*15 grains per 

 100 gallons. When we come to the Broomielaw, at 

 Glasgow, we find the amount of oxygen demanded had 

 risen to 0*00022 per cent, by weight, or 15 '40 grains per 

 100 gallons. 



"We then see it steadily diminishing; and when we 

 arrive at Port Glasgow, 20 miles down, it has become 

 equal to that at 6| miles above Glasgow. If we had 



SER. III. VOL. IV. p 



