Tin bent, a crackling sound known as the "tin cry" can be heard from the twinning of the crystals. Tin melts at low temperatures of about , the lowest in group 14. The melting point is further lowered to for 11 nm particles. β-tin (the metallic form, or white tin, BCT structure), which is stable at and above room temperature, is malleable. In contrast, α-tin (nonmetallic form, or gray tin), which is stable below , is brittle. α-tin has a diamond cubic crystal structure, similar to diamond, silicon or germanium. α-tin has no metallic properties at all because its atoms form
Anniversary + 200). In Latin, it seems that this rule did not apply precisely for 1½. While "secundus" is Latin for "second", and "bis" for "twice", these terms are not used such as in sesqui-secundus. Instead "sesqui" (or "ses") is used by itself. Many anniversaries have special names. "Etiquette in Society, in Business, in Politics and at Home" by Emily Post, published in 1922, contained suggestions for wedding anniversary gifts for 1, 5, 10, 15, 20, 25, 50, and 75 years. Wedding anniversary gift suggestions for other years were added in later editions and publications; they now comprise what is referred