The second paper concerns data reported by Dr. B.W. Richardson some time prior to 1878. This paper explored whether or not air contains a vitalizing substance necessary for life. While the results are provocative, they cannot be taken as definitive since one cannot rule out effects of oxygen toxicity unknown to Dr. Richardson.

We have seen that the air we breathe may be rendered impure by the presence in it of the products of breathing. We have seen that the air may be changed in quality by the influence of electrical discharge, and may possibly become injurious to health. There is yet another class of facts about the air which are newest of all, and which deserve to be mentioned on that account if on none other. To explain this set of facts I must trace the progress of research that led to them.

Many years ago the late Sir Benjamin Brodie and Mr. Broughton conducted a remarkable series of experiments on the effect of inhalation of oxygen gas in its pure form. The experimentalists named wished to determine what would be the effect of oxygen gas on animal bodies if the gas were breathed undiluted. Would the animal life be sustained for a longer or a shorter time in the pure oxygen? Would the combustion of the body be quickened in it? To arrive at a correct conclusion they placed living warm-blooded animals in chambers charged with simple oxygen, and beneath the chambers they placed, under a false perforated bottom, an alkaline solution, in order to absorb the carbonic acid which the animals produced in breathing. To the great wonder of the observers, they witnessed the fact that after a time the animals, inhaling what Priestley, the discoverer of oxygen, very properly called it, “vitaI air”–that the animals inhaling this vital air, instead of living more actively than they would live in an equal proportion of oxygen diluted as it is in the atmosphere, became languid and drowsy, and finally die in 1 state of sleep. When the observers removed the oxygen from the jar in which the animals had died, they found that the gas would support the combustion of a taper precisely as when it was freshly made, and they also found that it showed no evidence of the presence of carbonic acid gas. From these experiments, therefore, it was accorded that oxygen gas in a pure and simple state is narcotic poison, and as such it was set down in every text-book that treated on the subject, for many years.

In the early part of my career I was led from the study of anaesthetic vapors to go over this ground, which had been so singularly opened. I thought it possible that oxygen might be used so as to make it actually a sleep producer, but I started also with the idea in my mind that probably there was some error in the original experiments, that the whole of the carbonic acid produced by the animals in the oxygen had possibly not been removed by the experimentalists, and that a small remaining quantity of the known narcotic (carbonic acid) was after all the cause of the phenomena that had been observed. I therefore commenced to experiment in a different manner.

Instead of constructing a chamber with a false bottom, and with absorbing fluid underneath, I so constructed the apparatus that from a very large store of pure oxygen a current of the gas should steadily and continuously pass. In plain words, I ventilated a room perfectly with pure oxygen instead of common air. In such a room I found that for weeks life could be sustained, and that no narcotic symptoms were developed. I also found that if the temperature of the oxygen were maintained at summer heat, the combustion of an animal body in the gas was increased–that the appetite was made voracious, and yet that the excess of food did not prevent wasting.

Clearly, then, it occurred to me that the first experimenters were wrong, as I had suspected, and that carbonic acid gas was in their case the cause of the sleep.

But now a new light came on the subject which changed the view and gave a much more important reading, a reading that bears manifoldly on our present study, and others allied to it. I was not a rich experimentalist, and I found that to ventilate a good-sized experimental chamber for several weeks with oxygen was a process too costly for my means. So I devised this expedient. I made a larger store, eighty gallons, of oxygen in one reservoir, A, and by water suction I drew the gas gradually through the chamber into another reservoir of the same size, B, letting the place of the gas from reservoir A be taken by water let in from a tap. As the oxygen entered the chamber from A it was pure; as it passed out on its way to B it carried with it the carbonic acid that had been produced by the animals living in the chamber. In its exit from the chamber, in its course to B, the gas was stopped and purified: it was passed through sulphuric acid to remove ammonia, it was passed through potash to remove carbonic acid, and then it was passed through lime-water; and until it passed through lime water so clearly as to leave no trace of evidence of carbonic acid it was not admitted into the reservoir B. It was also tested in various ways in order to see if its physical qualities were those of pure oxygen.

When this purification was quite perfect the oxygen from B was repassed through the chamber into A with the same precautions as before, and I expected the same results as followed the process of ventilating with freshly-made oxygen. The expectation was not fulfilled. To my surprise, after a few passages of the oxygen gas from the reservoirs through the chamber it ceased to support the active life of all warm blooded animals. Frogs continued to live in it unaffected, but other animals passed into the same torpid, narcotized state as Sir Benjamin Brodie had discovered in his research.