446 



W. Ackroyd — The Circulation of Salt. 



a capacity of Q4-0'5 millions of gallons has in it some 55 tons of salt, 

 and as the water is being continually drawn off for municipal use, and 

 as continually being replenished by rains falling on a saltless area 

 of Millstone Grit, it follows that its chlorides must be derived from 

 the sea. The available data show further that if it had no outlet 

 and the inflow were balanced by the effects of evaporation it would 

 become Salter than the Dead Sea in a period of time less than one- 

 seventh of that usually assigned to the Pleistocene Age. The mind 

 naturally turns from such considerations to a case like that of the 

 Dead Sea, for it is little further removed from the Mediterranean 

 than Widdop is from the Irish Sea ; there is a rainfall in Palestine 

 higher than that of the Pennine hills, and in the past there has been 

 an intensity of meteorological conditions of which we at the present 

 day can form but an inadequate conception (Tristram, " The Land 

 of Israel," p. 320). All the conditions are present, but what of the 

 results ? The various points of similarity and of dissimilarity are 

 in favour of such a hypothesis ; it will be convenient to deal with 

 them after the next paragraph. 



Indiscriminate comparisons of salt-lake analyses lead to confusion. 

 This is illustrated by Professor Joly's remarks on p. 346 of this 

 Magazine for August. A principle is here overlooked which may 

 be thus briefly stated : — Where a solution of mixed salts, among 

 them being magnesium chloride and sodium chloride, undergoes 

 concentration, as the more soluble magnesium chloride increases in 

 amount the common salt is precipitated. The only reference on 

 which I can lay my hands at the moment is to the work of Precht 

 and Wittjen in 1881 (Journ. Chem. Soc, November, 1881, p. 978), 

 who show that a 20 per cent, solution of magnesium chloride at 

 20° C. dissolves only 5-1 per cent, of potassium chloride and 5-8 per 

 cent, of sodium chloride. Now in this strong light let us examine 

 the waters of the Elton Lake of the Kirghis Steppe as they vary 

 with the season : — 



On Professor Joly's line of argument the first and last analyses 

 ought not to belong to the same lake, but they are beautifully in 

 keeping with the principle I have enunciated. Nor does it at all 

 seem strange that in the case of the Great Salt Lake, where there is 

 so little magnesium chloride there should be so much common salt. 



