These kind of deposits are continually accumulating, and producing important changes, in the bed of the Nile, at Dongola, and in the Elbe, at Cuxhaven, and even choking up some of the harbours in the Baltic Sea. Dr. Trail analyzed a bergmehl from the North of Sweden, and found it to be composed of the minute shields of infusoria, about one thousandth of an inch in size, consisting chiefly of siliceous earth and alumina. A small quantity of this curious substance was found in County Down, Ireland, by Dr. Drummond, twenty years ago, while sinking a pit near Newcastle. MM. Cloquet and Breschet ate experimentally as much as five ounces of a silvery green laminar talc. Their hunger was completely satisfied, and they felt no inconvenience from the use of a kind of food to which they had not been accustomed. In parts of the East, use is still made of the Bole earths of Lemnos, which are clay mixed with oxide of iron. In Portugal and Spain, _bucaro_ clays are made into vessels, from which many are fond of drinking on account of the smell of the clay; and the women of the province of Alentejo acquire a habit of masticating the bucaro earth, and feel it a great privation when unable to indulge in this vitiated taste. In the Bolivian markets, Dr. Weddell saw a grey-coloured clay which was offered for sale. It is called _pahsa_, and the Indians of La Paz eat it with the bitter potato of the country. It is steeped in water, made into a kind of gruel, and seasoned with salt. At Chiquisaca a kind of earth called _chaco_ is made into little pots, and eaten like chocolate. Although their moderate use is not calculated to injure the system, their contribution to the nourishment of the body must be but small. In the valleys of the Sikkim Himalayas, a kind of red earth is chewed as a cure for the goître, but it is not stated to be regularly indulged in as an article of food either there or in any other part of India. Mr. Wallace relates that a little Indian boy died from the habit of dirt-eating—a very common and destructive habit among Indians and half breeds in the houses of the whites in the Amazon valley. All means had been tried to cure the lad of the habit. He had been physicked and whipped, and confined in doors; but when no other opportunity offered, he would find a plentiful supply in the mud walls of the house. The whole body, face, and limbs swelled, so that he could with difficulty walk, and not having so much care taken of him, he ate his fill and died. Those who have had much to do with children, will have noticed amongst some of them the germs of this propensity, which will occasionally develop itself in chewing pieces of pipe, slate pencil, chalk, and other substances of a like nature. Although not carried to so great an extent as to become injurious, cases of this kind are far from being, among school children, either exceptional or uncommon.