( 51 ) 



do\A'invaiTl llin»ii,iiii llic did sca-clay. to have heen \('i'\- small coiii- 

 pai-ed AN'itli llie aiiioiml of Civsli walci- proscMit. (\)iise(|ii('iill\ llic 

 oidy Fource of supplv of fresh walcr (o \Uv diiiixiimi lias hoon (lio 

 afflux from the dimes. Al the same time 1 veiiliii-e the sii|>positi(ni 

 that part of the fresh water whioh a thousand _v ears a^'o was |)i-eseiit 

 in the dilu\ium under the pohh^-land is still pros(Mit llioro now. 



Another (piestion arising here is whether saU water rises upward 

 from below. About former times nothing- can be slated with certainty 

 in this respect; for the present time it is I'eiidered pi-obable b\- iIk^ 

 circnmstance that the water of the Haarlemmermeer polder contains 

 more chlorine than can be derived from the afflux if no salt water 

 from below is added to it. Therefore 1 have tried to e:-timate, though 

 roughly, the (piantity of chloi-ine, discharged by Ivijnland and the 

 quantities entering Ivijnland in another way than from below, assuming 

 that the quantity of chlorine withdrawn from the ground by plants 

 is equal to the quantity furnished by manuring, which supposition 

 is reasonable. 



Rijnland discharges anjiually on the a^'erage 476 million M\ of 

 water ; how much chlorine this contains is not known, but from the 

 data for the percentage of chlorine of the water of the bosom ^) a 

 figure may be derived which is too small and another which is too 

 large, which figures 1 take to be 105 and 315 mg. per litre, givin"- 

 an annual discharge of 5().()0() or 150. 000 tons of chlorine. 



The qnantities of chlorine arri\ing into Jiijnland are, besides that 

 from the groundwater below 1. the sea-sj>ray ; assuming that this 

 chiefly falls on the dunes we can estimate it; tlie <lunes that discharge 

 water into Rijnland ^vill supply alxuit 20 million lAl-'. of water 

 annually ; this water contains 40 mg. chlorine ])ei- litre, making 

 800 tons of chlorine ; adding to this what is blown ovei- the dunes 

 we obtain a total of 1500 tons; 2. the fresh water which is let in, 

 amounting on the average to 125, million M\ per year, containini»' 

 40 mg. per litre, which malvcs 5000 tt)]is ; 3. the watei' thi'ough 

 locks ; it is difficult to estimate an average percentage of chlorine 

 here, since one lock ((iouda) admits fresh water to the bosom, others 

 (Spaarndam, Overtoom, etc.) water \Nitli a high jiercentage of chlo- 

 rine ; I thiidv 2000 mg. })er litre a sufficiently high estimate; putting 

 the water let in through locks at 5 million M''. this makes 10.000 tons; 

 4. what human society discharges into the bosom ; this amount is 

 difïicult to estimate ; |)utting it at 3500 tons, the total amount becomes 



^) Mededcelingeii onilrcnt di' Cieologic van Xcdoiland, no. 2G, hy Dr. J. Lorié 

 pp. 8— U. 



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