They now walked on in silence for a short time, till Agnes’s attention was caught by a building which some men were busily employed in pulling down. “What is that, mamma?” cried she: “and why are those people taking off the roof?” Mrs. Merton pointed to a portion of the walls that remained standing, and on which the words “salt-works” might still be read. “Salt-works!” repeated Agnes; “what is salt made of, mamma?” “Salt,” said Mrs. Merton, “can hardly be said to be made, as it is a mineral which is formed naturally in the earth, and which we procure in three different ways. Sometimes it is dug out of the salt-mines, as at Northwich in Cheshire, and in the Austrian dominions; but this kind of salt is coarse and dark-coloured. Another way of procuring it is from salt-springs; that is, from water which has become saturated with salt in its passage through the earth, as at Nantwich and other places in Cheshire, and at Droitwich in Worcestershire; and this salt is what we have in common use. The last kind of salt is what is made from the sea-water, and most of the works that have been erected for this purpose in England are in Hampshire, particularly in the Isle of Wight.” “And how do they get the salt out of the salt-water?” asked Agnes. “By boiling it,” said her mother, “in large shallow pans, such as that which you see before you.” While they were examining the pans, Agnes asked her mother a great many questions respecting the salt-works, and Mrs. Merton told her, that the salt obtained from sea-water is of so much coarser kind than that obtained from the salt-springs, that it is principally used for curing meat, and for manuring the land. “Ah!” said Agnes, “that reminds me of a question that I have often wished to ask you, mamma. When I was at Shenstone, my cousin George told me that salt would be excellent manure for my plants, and I put some on my annuals, which were just coming up, and, would you believe it, mamma, it killed them every one.” “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.”