পাতা:পদার্থবিদ্যাসার.djvu/১৭৭

166 Tut. No : they are of two different qualities: 1st, Such as will scratch glass; and 2ndly, Such as will not scratch glass. Pup. What are the principal kinds ofthose which scratch glass 2 Tut. Among these are included precious stones, such as the diamond, the ruby, the topaz, the emerald, the amethyst, the cornelian, the crystal, &c. Pup. Among these, which are io be considered most valuable * - Tul. They are all reckoned valuable according to their size and lustre: the diamond stands first in value. Pup. What may be the worth of a diamond * Tui. As the value of diamonds is ascertained by their weight, some are worth 100 Rupees, some 300, and others 1000. One taken from Madras was sold in England for £185,000, and one found in South Ame. rica, was valued at £5,644,800. The most valuable diamonds are those which are perfectly transparent and of a suow-white colour. Pup. W here are these precious stomos found ? Tut. They are found in mines, in rocks, and amongst the sand and gravel of rivers. Pup. Besides these precious stomes, are there not some others of this order, valuable for their common uses 2 Tut. Yes. Flint and saud are reckoned in this order; and they are extremely useful, as from them our glass is manufactured. ', Pup. What stones are included under the head of those that will mot scratch glass? - Tut. Among these are included the different kinds of earth from which our bricks, basins, porcelain, &c, are made. -