The increase of atomic weight from silicon 28 to germanium 72 is 44--that is, about the same difference as there is in the atomic weights of chlorine and bromine; between germanium and its next analogue, _tin_ (Sn = 118), the difference is 46--that is, almost as much as the amount by which the atomic weight of iodine exceeds that of bromine. Metallic tin is rarely met with in _nature_; it occurs in the veins of ancient formations, almost exclusively in the form of oxide, SnO_{2}, called _tin-stone_. The best known tin deposits are in Cornwall and in Malacca. In Russia, tin ores have been found in small quantities on the shores of Lake Ladoga, in Pitkarand. The crushed ore may easily be separated from the earthy matter accompanying it by washing on inclined tables, as the tin-stone has a specific gravity of 6·9, whilst the impurities are much lighter. _Tin oxide is very easily reduced_ to metallic tin by heating with charcoal. For this reason tin was known in ancient times, and the Ph[oe]nicians brought it from England. Metallic tin is cast into ingots of considerable weight or into thin sticks or rods. Tin has a white colour, rather duller than that of silver. It fuses easily at 232°, and crystallises on cooling. Its specific gravity is 7·29. The crystalline structure of ordinary tin is noticed in bending tin rods, when a peculiar sound is heard, produced by the fracture of the particles of tin along the surfaces of crystalline structure. When pure tin is cooled to a low temperature it splits up into separate crystals, the bond between the particles is lost, the tin assumes a grey colour, becomes less brilliant--in a word, its properties become changed, as Fritzsche showed. This depends on the peculiar structure which the tin then acquires, and is particularly remarkable because it is effected by cold in a solid.[33 bis] If such tin be fused, or even simply heated, it becomes like ordinary tin, but is again changed when cooled. When in this condition tin has a specific gravity of 7·19. Similarly, tin is obtained by the action of the galvanic current on a solution of tin chloride; it then appears in crystals of the cubic system, and has a specific gravity of 7·18--that is, the same as when cooled.[34] [33 bis] Emilianoff (1890) states that in the cold of the Russian winter 30 out of 200 tin moulds for candles were spoilt through becoming quite brittle. [34] The tin deposited by an electric current from a neutral solution of SnCl_{2} easily oxidises and becomes coated with SnO (Vignon, 1889).