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.
Hydrogen sulfide is the chemical compound with the formula H 2S. It is a colorless gas with the characteristic foul odor of rotten eggs; it is heavier than air, very poisonous, corrosive, flammable, and explosive.ydrogen sulfide is slightly soluble in water and acts as a weak acid, giving the hydrosulfide ion HS â (pKa = 6.9 in 0.01-0.1 mol/litre solutions at 18 Â°C). A solution of hydrogen sulfide in water, known as sulfhydric acid or hydrosulfuric acid, is initially clear but over time turns cloudy.