252 On the Changes produced in Atmospheric Ait 



We procured the gas from hyperoxygenized muriate of* 

 potash by means of muriatic acid, and mixing it with a 

 known portion of gaseous oxide of carbon in a flint stopper 

 bottle, the mouth of which was immersed in mercury for 

 twenty-four hours,-the gaseous oxide of carbon was converted 

 into carbonic acid gas, as was proved by its effects upon lime- 

 water, which, when both the gases are pure, absorbs them 

 entirely after they have remained together for twenty-four 

 hours ; it was plain, therefore, that we had the means of 

 (detecting gaseous oxide of carbon, and doubtless carburetted 

 hydrogen, if any should be contained in the expired gas. 

 From a conviction of the importance of these experiments we. 

 were determined to take nothing upon trust. 

 Fifteenth Experiment. 



We repeated the ]4th experiment with a little variation. 

 In this case we employed only one of the mercurial gaso- 

 meters, into which exactly 300 cubic inches of atmospheric 

 air were admitted. The operator having made an easy ex- 

 piration, applied his mouth to the cock at the top of the bell 

 glass,, and the time being noted, began to breathe ; in less 

 than a minute he found himself obliged to take deeper and 

 deeper inspirations; and at last the efforts of the lungs to 

 take in air became so strong and sudden, that the glass was 

 in some danger of being broken against the side of the gaso- 

 meter. A great sense of oppression and suffocation was now 

 felt in the chest, vision became indistinct, and after the se- 

 cond minute his whole attention seemed to be withdrawn 

 from surrounding objects and fixed upon the experiment. 

 He now experienced that buz in the ears which is noticed 

 in breathing nitrous oxide, and after the third minute he had 

 only sufficient recollection to close the cock after -an ex- 

 piration. This secured the result of the experiment ; but 

 he became so perfectly insensible that, on recovering, he 

 was much surprised at finding his- friend and the assist- 

 ant on the table in the act of supporting him. It was 

 noticed that he had made thirty-five inspirations during 

 the experiment. We now examined the air which had been 

 so treated. 



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