252 Transactions of the American Institute. 



introduce, is the burning of phosphorus in tliis gas. This is justly 

 described as one of the most brilliant of all chemical experiments. 

 In the air phosphorus burns with vigor, but as it passes into the 

 atmosphere of pure oxygen, the union of this gas with the com- 

 bustible is so active, and the light emitted so intense, that one may 

 as well attempt to gaze on the noonday sun as on the jar in which 

 phosphorus is burning in oxygen. 



Having described the constituents that are always present in the 

 same proportions in the air, whether it be taken from the sealed 

 vases of Herculaneum, or from the atmosphere as it now^ is, it remains 

 that we should demonstrate that these gases are actually present. 

 To accomplish this, I take a jar half filled with a colorless gas called 

 the deutox3"de of nitrogen, and, raising it from the water in which it 

 is resting, allow air to flow in. The gas instantly unites with it, 

 brown fumes are produced, which are converted into an acid that 

 unites with the water, as we may show by the addition of a little 

 blue litmus, which is instantly turned red. Examining the gas that 

 remains in the jar, we find that it cannot support combustion, it is 

 therefore the nitrogen with which we are already acquainted. 



Turning from this brief review of the properties of the leading 

 constituents of the air, let ns reflect for a moment on the advantages 

 gained by the mixture of these two bodies. Either gas alone is 

 incompetent to carry on the manifold processes connected with our 

 daily life. Existence in an atmosphere of nitrogen is impossible, 

 and even though we might live in a pure oxygen air, we should be 

 confined to a diet of raw meats and grain, for it would be impossible 

 to use fire in the preparation of food, since both the viands and the 

 utensils employed in their preparation, would be consumed in the 

 fierce heat that oxygen generates ; and if, as many think, man's 

 nature is dependent on his food, we should be but little advanced 

 beyond the lowest savages on our globe. 



By means of suitable and ingeniously constructed mechanical con- 

 trivances, which we cannot now stop to describe, the air is conveyed 

 into the lungs and there brought into intimate contact with the blood 

 as it courses through these organs. The oxygen is absorbed by the 

 discs or floating cells of the fluid, and conveyed to the remotest 

 recesses of the system, to assist in carrying on the processes of 

 life. While these cells are laden with the vitalizing gas, they have a 

 bright red or arterial color, but when the oxygen is lost their bril- 

 liant tint disa[ipears, they assume a darker hue, ajid are returned to 



