100 CLASSICS OF MODERN SCIENCE 

 noxious as possible, so as not to be affected by nitrous air ; when, to 

 my surprise again, I found that though it had been breathed so long, 

 it was still better than common air. For after mixing it with nitrous 

 air, in the usual proportion of two to one, it was diminished in the 

 proportion of four and one-half to three and one-half ; that is, the 

 nitrous air had made it two-ninths less than before, and this in a very 

 short space of time; whereas I had never found that, in the longest 

 time, any common air was reduced more than one-fifth of its bulk by 

 any proportion of nitrous air, nor more than one-fourth by any phlo- 

 gistic process whatever. Thinking of this extraordinary fact upon 

 my pillow, the next morning I put another measure of nitrous air to 

 the same mixture, and, to my utter astonishment, found that it was 

 farther diminished to almost one-half of its original quantity. I 

 then put a third measure to it ; but 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 hav- 

 ing 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 one and one-half to two- thirds 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 

 calcinatiis 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 



