Before 2500 BC the earliest black writing inks were developed. There are made by mixture of carbon, usually lampblack, in water stabilised with a natural gum or materials like egg albumen. Inks nowadays are rather more complex. Modern day inks contain an ingredient called pH modifiers, these pH modifiers slows down the process of the ink drying quickly. Most inks were made out of foul smelling hydrocarbon organic chemicals, like xylene. Although these chemicals provide a desirable permanency, they are highly toxic. Today, xylene may be used in some markers (e.g. Sharpie King Size), but most markers are now replaced with an alcohol solvent. Alcohol, such as ethanol or isopropanol, is more environmentally friendly and even smells better. It also evaporates quickly, allowing permanent markers to dry faster.