Oxygen tents are now coming into extensive use for the treatment of pneumonia. As a rule, analysis of the atmosphere in these tents is unnecessary. If the gas is passed in at the rate of 7 or 8 liters a minute, there is a considerable diffusion of air inward and oxygen outward through the bedclothes, even if the curtains of the tent are tucked in tightly. The result is a concentration of 40 to 50, or at most 60, per cent of oxygen. Higher concentrations are inadvisable. The reactions of the patient are really the most significant indication of the best concentration.
For purposes of investigation, however, and particularly for a special form of tent for the administration of mixtures of oxygen and carbon dioxide soon to be introduced, gas analyses are convenient. But as precise gas analysis is a highly specialized technic, which is usually unfamiliar to a hospital