astonishment, found that it was farther diminished to almost one half of its original quantity. I then put a third measure to it; hut this did not diminish it any farther; but, however, left it one measure less than it was even after the mouse had been taken out of it.
Being now fully satisfied that this air, even after the mouse had breathed it half an hour, was much better than common air, and having a quantity of it still left sufficient for the experiment, viz., an ounce measure and a half, I put the mouse into it; when I observed that it seemed to feel no shock upon being put into it, evident signs of which would have been visible if the air had not been very wholesome; but that it remained perfectly at its ease another full half hour, when I took it out quite lively and vigorous. Measuring the air the next day I found it to be reduced from 1
12
to 2-3 of an ounce measure. And after this, if I remember well (for in my register of the day I only find it noted that it was considerably diminished by nitrous air) it was nearly as good as common air. It was evident, indeed, from the mouse having been taken out quite vigorous, that the air could not have been rendered very noxious.
For my farther satisfaction I procured another mouse, and putting it into less than two ounce-measures of air extracted from mercurius calcinatus and air from red precipitate (which, having found them to be of the same quality, I had mixed together) it lived three quarters of an hour. But not having had the precaution to set the vessel in a warm place, I suspect that the mouse died of cold. However, as it had lived three times as long as it could probably have lived in the same quantity of common air and I did not expect much accuracy from this kind of test, I did not think it necessary to make any more experiments with mice.
Being now fully satisfied of the superior goodness of this kind of air, 1 proceeded to measure that degree of purity with as much accuracy as I could, by the test of nitrous air; and I began with putting one measure of nitrous air to two measures of this air, as if I had been examining common air, and now I observed that the diminution was evidently greater than common air would have suffered by the same treatment. A second measure of nitrous air reduced it to two thirds of its original quantity, and a third measure to one half. Suspecting that the diminution could not proceed much farther, I then added only half a measure of nitrous air, by which it was diminished still more; but not much, and another half measure made it more than half of its original quantity; so that, in this case, two measures of this air took more than two measures of nitrous air and yet remained less than half of what it was. Five measures brought it pretty exactly to its original dimensions.
At the same time air from the red precipitate was diminished in the same proportion as that from mercurius catcinatus, five measures of
