Sodium Alginate from Kelp: Stanford's Soluble Algin

Kelp holds algin, which sodium carbonate dissolves as sodium alginate. Stanford's process, as Thorpe gives it (1912): soak the kelp in cold water, boil it with soda and filter, throw down alginic acid with hydrochloric acid, then redissolve that in soda. Dried thin on glass it makes a clear, flexible sheet. The picture: our own drawing.