Abstract
Visking sausage casing is impermeable to native proteins but permeable to proteose. Three-fourths inch casing will not stand a pressure exceeding the osmotic pressure of blood colloids but onehalf inch casings may be obtained. Ox blood serum diluted with one volume of water and saturated with toluene, was filtered through three-fourths inch casing by tying one end and sealing it with collodium and coiling 10 feet in an oval aluminum tray covered with a metal top sealed with vaseline. Two feet of the casing protruded from a hole in the cover and was supported vertically. The casing was filled with the serum and the pressure adjusted by the height of the vertical portion containing serum. A number of cc. per hour were filtered by a pressure little in excess of the osmotic pressure of the proteins. The ultrafiltrate contained the same concentration of chlorides as the serum, 70% of the calcium and 60% of the total phosphorus. The last 2 figures might have been different if the serum had not contained some albumose.
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