Early wheels were simple wooden disks with a hole for the axle. In the early Roman empire, most horse-carts used a design featuring two chords across the wheel. The spoked wheel was invented much more recently, and allowed the construction of lighter and swifter vehicles.
Chromium(III) sulfide. Chromium(III) Sulfide is the inorganic compound with the formula Cr2S3. It is a brown-black solid. Chromium sulfides are usually nonstoichiometric compounds, with formulas ranging from CrS to Cr0.67S (corresponding to Cr2S3). Preparation.
Gaseous sulphur has the same chemical formula as solid or liquid sulphur; S8. A sulphur atom forms covalent bonds with other sulphur atoms very easily and the most stable molecule is comprised of eight atoms arranged in a crown-shaped octagonal ring. i.e.;-.