equally absurd to conclude, that the fine green observed in oysters taken from artificial beds, is the effect of copperas; as this substance, or a solution of it, is inevitably fatal to all fish.
Oysters are esteemed as excellent food, and are eaten both raw and dressed, in various ways: in a fresh state, however, they are doubtless preferable; for, by cooking, they are in a great measure deprived of their nourishing jelly, and of the salt-water which promotes their digestion in the stomach. Hence raw oysters may be used with equal advantage by the robust, the weak, and the consumptive. Independently of the nutritive effects peculiar to this shell-fish, it generally tends to open the bowels, especially if a certain quantity be swallowed at one meal: hence to persons of a costive habit, they afford a dietetic supper.
The shells of the oyster, like those of other crustaceous fish, are composed of calcareous earth, and animal glue. They possess no medicinal virtue superior to common lime-stone or chalk; but, by calcination, they yield a quick-lime, which is perfectly free from any metallic or other fossile substance; and being less permeable to water, when mixed with sand, it is better calculated for the plastering of walls in damp situations. Hence the Dutch prepare their excellent mortar generally of marine shells burnt into lime; which makes a most durable cement. The great importance of this fact, in point of health and economy, deserves equal attention; so that the immense quantities of oyster-shells annually thrown away in London, Bristol, and other populous places, might easily be converted into a very useful shell-lime.
P.
Paddock-pipe. See Horse-tail, the Marsh, vol. ii. p. 493.
Paddow-pipe. See Mare's-tail, the Common.
Pagil, or Paigles. See Cowslip, the Common.
PAINT, a term used to express more particularly the preparations employed in painting houses.
The principal article in the various compounds being white-lead, the grinding of which is extremely detrimental to health, we shall state the following process, lately invented by M. A. A. De Vaux, and communicated for the benefit of the public:—should it prove to be an effectual substitute for the pernicious paint now employed, it will be of inestimable service to society. He directs two Paris pints of sweet skimmed-milk (two quarts English measure); six ounces (612 ounces English averdupois) of fresh slaked lime; four ounces of nut, caraway, or linseed oil, and three pounds of Spanish white, to be used in the composition. The lime must first be introduced into a stone vessel, to which should be added such a proportion of milk as will produce a mixture resembling thin cream. Next, the oil is to be gradually poured in; the whole being gently
