]9'22.] The Agricultitral Value of Sea-Sand. 593 



Composition and Effects. — Its chemical effects on the soil 

 would appear to be confined entirely to the action of the car- 

 bonate of lime Vv'hich it contains in the form of powdered shell, 

 for no other substance of agricultural importance can be found in 

 appreciable quantity. It has been suggested that its value is 

 due partially to the sodium chloride which it has retained from 

 the sea water, but only the faintest traces of this substance can 

 be found in sand taken direct from the beach, while in the 

 bank or dune samples there would be even less. 



In a series of carefully conducted tests carried out by one of 

 the writers the following results were obtained : — 



Percentage of Awount of salt 



Sltuat 'um. sodmw, cidoride in a ton of 



la sand. sand as carted. 



F'enzance lug sand (wet) ... 0'78 ... 171 lb. 



I'orthtowan beach (damp) ... 0'19 ... 4^ lb. 



Gwithian Bank (dry) ... O'OOB ... 1 oz. 



I^nde Bank (dry) ... 0-008 ... 2f oz. 



Harlyn Bank (dry) ... 0-002 ... | oz. 



Neither phosphates nor salts of potash or magnesia are present, 

 none of these forming part of the material of the rocks and cliffs 

 of this coast in determinable quantities. Samples of sand from 

 most of the beaches around the coast have been tested by one 

 of the writers and the proportion of carbonate of lime and the 

 mechanical composition determined. 



The table on p. 594 gives the percentage of carbonate of lime, 

 its equivalent as lime (CaO), the amount of lime (CaO) in a ton 

 of sand and the mechanical composition of samples around the 

 coast of Cornwall from Bude to Plymouth. 



This table shows that percentage of lime and mechanical com- 

 position have little connection or bearing on one another. One 

 frequently hears it suggested that the fine sand is superior to the 

 coarser in lime content; that blown sand is finer and therefore 

 superior; that beach sand is better than bank, etc., but the table 

 does not definitelv bear out anv of these contentions. 



The cost to the farmer of the lime in the sand will depend 

 almost solely upon the distance he has to cart it, the charge 

 made for the sand when taken from the bank beins: merelv a 

 nominal one, while it may in most cases be taken from the beach 

 free of cost. At the present time burnt lime is 43s. per ton at 

 Truro delivered at the Railway Station, while ground limestone 

 is 38s. per ton at the same place. As one ton of burnt lime is 

 equal to If tons of ground Hmestone from the same quarry it is 

 very evident that burnt lime is much the cheaper of the two. 



B 



