Ox bladder

Van t Hoff s theory of solutions was based on the phenomenon of osmotic pressure, some account of which will first be given. The purification of salt by putting it in an ox-bladder, and immersing this in water, which penetrates the bladder and forms a solution of salt, which is then evaporated, is described in a work of 1529. Van Helmont found that salt passes with water through a bladder, and so explained the passage of food (chyle) through the walls of the intestines. 

Scheele s pioneering work was a great achievement, even more so because of the very primitive equipment available in his laboratory (Figure 44.2). For his experiments with gases, ox bladders and common bottles were utilized. 

Certain people may object to the finings used in wines on moral grounds, but the lack of relevant additives listed on the label make it impossible for the consumer to be able to choose. Permitted finings include isinglass (from the swim bladder of certain tropical fish, especially the Chinese sturgeon), egg albumen, gelatine (from animal bones), modified casein (from milk), tannin (from wood), chitin (from the shells of crabs or lobsters) or ox blood (rarely used today). Non-animal alternatives include bentonite, kieselguhr and kaolin clays, and silica gel or solution. 

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