In order to purify cotton, carded cotton sliver is cut into short lengths, is extracted, preferably in a Soxhlet apparatus for 18 hr. with chloroform followed by 95% ethanol for a further 18 hr. It is vigorously boiled for 8 hr. in an atmosphere of nitrogen with 1% sodium hydroxide with a liquid ratio of 50 ml. per g., washed with water until free from alkali, and then washed sequentially with acetone, ethanol, and ether. The cellulose is then dried under reduced pressure at 20 degrees.