The intravenous route was early tried with chloroform and was given up as too dangerous. Then Burkhardt in 1911 used ether, 5 per cent. in normal saline at 82.4o F. (280 C), and found it suitable. By this method apparently the regulation of the degree of anesthesia is easy, and the breathing from the beginning is regular. Complete anesthesia, is attained within five minutes, and its maintenance is dependent on keeping a proper balance between the amount of ether introduced and that excreted by the lungs. Connell says that to establish anesthesia it takes 50 c.c. per minute of 5 to 7 per cent. ether for from two to five minutes. On stopping the inflow, return to consciousness is prompt. The large quantity of saline predisposes to heart failure and pulmonary edema, and may result in abnormal oozing at the wound. The use of a vein involves the risks of thrombosis and embolism. The high percentage of ether at the point of introduction may produce hemolysis. A preliminary dose of morphine with atropine or scopolamine is customary.

Paraldehyd has been recommended for intravenous anesthesia by Noel and Soutter (1913). From 5 to 15 c.c. with an equal amount of ether are dissolved in 150 c.c. of 1 per cent. saline, and injected at the rate of about 5 to 10 c.c. per minute. A mild narcosis comes on at once, and there is deep unconsciousness in one minute. This ceases soon after the stoppage of the infusion. Paraldehyd is detected in the breath in ten seconds. The anesthesia is followed by easy recovery or by sleep. It is a rapid method for minor operations or to check convulsions.

Hogan and Hassler say that paraldehyd is excreted too rapidly and may severely irritate the larynx and bronchi.