Wood,1in 1884, in an article to substantiate the inhibitory action of magnesium sulphate, wrote that its intravenous injection was not new. Then, in 1905, the important work of Meltzer2was published. This has been the basis for the subsequent use of the salt in controlling the convulsions of tetanus, and in establishing its anesthetic properties. Moreover, he definitely advised against intravenous administration because of the danger of provoking respiratory failure. In 1916, Meltzer3gave a comprehensive outline of the action and use of magnesium sulphate in tetanus, and, in a measure, retracted his previous definite statement regarding the risk of intravenous injection, yet emphasized a probable danger. Weed and McKibbon,4in 1919, reported an important series of experiments, demonstrating that cerebrospinal fluid pressure and brain bulk may be varied by hypertonic and hypotonic solutions. They also stressed the fact that certain hypertonic solutions—sodium chloride— caused