“That,” said Mrs. Merton, “was because the manure was too strong for them, and you no doubt put a great deal too much. Salt, to do good to plants, should be given to them in very small quantities, as, though all plants require some mineral substances to be mixed with their food to keep them in health, it is in such small quantities that in some plants it is only in the proportion of one to four thousand; and where mineral substances are required in the greatest quantity for the nourishment of a plant, it is only in the proportion of about ten to one thousand.”
“I do not think I quite understand that, mamma,” said Agnes.
“Well,” returned Mrs. Merton, “at any rate you will remember, that though a very small quantity of salt may be useful to plants, a large quantity will kill them, and that, consequently, it is much safer for inexperienced gardeners not to give them any.”
“I remember once being told that all the places that produce salt end in wich; but the name of this place is Cowes.”
“I have heard that the word wich is derived from the Saxon, and that it signifies a salt-spring,” said Mrs. Merton, “but of course that does not apply to salt procured from the sea.”
Mrs. Merton and her daughter had now reached the beach, and ordering a boat from one of the boatmen lounging about, they stepped into it to return to West Cowes.
“But, mamma,” said Agnes, who was still thinking of the salt-works, “is this the water they use for making salt? This is the Medina, and not the sea, and the Medina is a river, is it not?”
“This part of the Medina,” said Mrs. Merton, “is what is called an estuary; that is, an arm of the sea mixed with the waters of a river; the water of this estuary is salt, and affected by the tides as far as Newport.”
“What makes the waters of the sea salt?” asked Agnes.
“That is a very difficult question to answer,” said her mother, “but it is supposed that rivers carry salt from the earth they run through, into the sea; and as the water in the sea is continually being evaporated by the heat of the sun, the quantity of salt, in proportion to the quantity of water, soon becomes much greater in the sea than in the river, and hence the water becomes much salter.”