CLYDE SEA AREA. 707 



truth for the Gortans Basin. It is probable that the tidal rise in a loch, especially in its 

 upper reaches, takes the form of an oscillation in a plane slightly inclined to the 

 horizontal, i.e., an upthrusting of the mass of water from nearer the mouth, and a return 

 to the state of equilibrium at low water. An average velocity of 1 knot for the surface 

 current appears from the Admiralty Charts to be a maximum estimate of the surface tidal 

 currents in Loch Fyne." At that rate, since the ebb stream lasts about one hour longer 

 than the flood, a given particle of water on the surface would be carried 1 mile down 

 the loch by each tide supposing the weather calm, and the lower 7 miles would be 

 completely changed. In the absence of more detailed observations, it is impossible to 

 do more than guess at the time necessary for complete change of water in the upper 

 basin. Probably the direction and force of the wind are very potent factors in deter- 

 mining it. 



Chemistry of Water in the Clyde Sea Area. 



During the salinity trips of November 1886 and of February, March, May, June, 

 and September 1887, samples of water were collected with special precautions and sent 

 to Professor Dittmae's laboratory in Glasgow, where they were analysed by Mr A. 

 Dickie. The results of analysis were communicated to this Society and published in 

 the Proceedings (Proceedings R. S. E., xiv. 422-427, xv. 283-286). The attempt to 

 determine the suspended solid matter in the water was abandoned on account of the 

 great labour involved in filtering a large volume of liquid, and weighing a very small 

 residue. Mr Dickie determined in each case the amount of chlorine present per litre of 

 water, the amount of sulphuric acid, and the alkalinity. In his papers he expresses the 

 alkalinity both in milligrammes of carbonic acid per litre of sea. water analysed and in 

 milligrammes per 100 parts of total salts (i.e., per 55*43 parts of chlorine). In the first 

 paper he reduces the value of the sulphuric acid determinations to milligrammes per 

 milligramme of chlorine as well. I have calculated the results in his second paper to the 

 same units, and have grouped the results in various ways, in order to discover any 

 relations of general interest which they may contain. 



Eeference has already been made to the chlorine determinations as forming a valuable 

 means of testing the accuracy of hydrometer work on which the foregoing discussion of 

 salinity depends. In order to study the proportions of sulphates and carbonates I shall 

 make use exclusively of the ratios to amount of chlorine, in order to eliminate the 

 accidental variation due to salinity. 



The whole set of observations (117 in number) were first written out in a column in 

 the order of their amount of chlorine, and means were taken of eight groups comprising 

 different ranges of salinity, so as to determine whether the amount of fresh water present 

 notably affected the proportions of sulphuric and carbonic acids. Table XXXV. is the 

 result. 



