Barium chloride is even more poisonous and only the most minute doses can be given. It is, however, by far the most powerful of all these purgative salts. Its action is extremely rapid and violent. When given intravenously it is best to mix it with about five times its volume of m/6 NaCl solution. Thus 1 c.c. of a mixture of 5 c.c. m/6 NaCl + 1 c.c. m/6 BaCl_{2} injected into the circulation causes almost immediately most violent intestinal movements. The loops contract so that they resemble white firm cords. They rise up from one another so that they seem to stand erect and the squirming, twisting movements become extremely active. The intestinal contents are hastened on and can be watched through the thin walls moving rapidly from loop to loop. The actual passage of faeces takes place in a very short time. It begins with solid faecal masses, followed quickly by semifluid faeces. The quantity passed is sometimes very considerable. As will be shown in a later chapter, the injection of BaCl_{2} into the blood causes not only an extensive increase in the peristaltic movements, but brings about also an increase in the quantity of fluid secreted into the intestine. The subcutaneous injection of 2-3 c.c. m/6 BaCl_{2} produces in 5-10 minutes an effect quite similar to that described for the intravenous injection of the salt. A rabbit weighing 1,200-1,500 g. does not, however, usually recover from a dose greater than 2.5-3 c.c. m/6 BaCl_{2} given subcutaneously, and a smaller quantity is sufficient to produce purgation. Boehm[28] gives as the lethal dose of BaCl_{2} when given intravenously for rabbits O.1-0.2 g., for cats 0.03-0.05 g., for dogs O.1-0.2 g. When given subcutaneously it is O.12-0.18 g. for rabbits and cats and O.3 g. for dogs. When BaCl_{2} is taken into the stomach it is absorbed quite slowly, but its effects are similar to those described above. Active peristaltic movements and purgation result, and in many cases vomiting is seen in dogs. It is clear from these experiments that all salts do not act equally on the intestine. Sodium chloride may be introduced in large quantities into the circulation without causing increased peristalsis or defaecation. Sodium oxalate and phosphate (Na_{2}HPO_{4}) exert only a slight action. Sodium phosphate, according to Bunge, increases the fluid in the intestine. Sodium tartrate produces quite active movements of the intestine and is considerably stronger in its action than either the oxalate or phosphate. Sodium citrate and sulphate as described above are quite constant and vigorous in their action, while barium chloride is by far the most powerful of all these saline purgatives. Sodium fluoride also acts very rapidly.