Experiments have recently been made to test the effect of adding calcium salts to barium chloride and feeding the two mixed with some edible substance to mice. BaCl_{2} is a common poison to employ for mice and rats. It was found that the mice eating food containing barium carbonate alone died, while those eating the mixture of calcium carbonate and barium carbonate in the food were unharmed.[56] When loops of the intestine are entirely removed from the body and placed in sodium chloride solution, active movements begin, as will be described in detail in a later chapter. These movements continue 40 to 45 minutes or longer if the proper conditions of temperature, etc., are preserved. If, however, CaCl_{2} be added to this solution the movements are inhibited. Also loops placed in pure m/6 CaCl_{2} solution lie perfectly quiet. A peculiar action of calcium which will be described in detail later on is shown in the following experiments: A loop of rabbit’s intestine was removed from the body and placed in a solution of m/6 LiCl. After moving rhythmically for about 15 seconds the loop came to rest. A loop similarly placed in m/6 CaCl_{2} solution showed no movements. In a mixture, however, of 50 c.c. m/6 LiCl + 5 c.c. m/6 CaCl_{2} the initial movements seen in the pure LiCl solution were absent and the loop remained quiet for 10-15 minutes. Then sudden sharp constrictions appear in the loop, followed by violent contractions of the whole loop. The loop twists and coils upon itself and continues to move in this extremely active manner for 30-45 minutes or longer. The control loops in pure LiCl and pure CaCl_{2} remain motionless during all this time. A similar phenomenon occurs with a mixture of NaCl and CaCl_{2}. In NaCl, however, the initial movements are much more conspicuous and may continue for an hour. These are inhibited in the mixture of NaCl and CaCl_{2}, and after 10-15 minutes movements of an entirely different character appear, resembling those described for mixtures of LiCl and CaCl_{2}. Sharp constrictions and violent twistings persist for 30 or 40 minutes. These peculiar contractions do not occur in mixtures of LiCl and NaCl, nor in mixtures of CaCl_{2} and MgCl_{2}. In addition to their action on the intestine, calcium and magnesium have a very definite action on other organs of the body, more especially the kidney. It was found[57] that both calcium and magnesium chlorides inhibit the flow of urine. This is shown in the following tables taken from the paper referred to. Rabbit--cannula placed in bladder. No urine flowed in the first or second periods of 10 minutes before the NaCl solution was injected. Time Salts other than m/6 NaCl Urine NaCl injected injected in c.c. in c.c.