810 Experiments 



oxygen and formed 514 cc. of carbonic acid, the consumption of 

 oxygen at a half-atmosphere had dropped to 343 cc. and the pro- 

 duction of carbonic acid to 418 cc. The same result in Experiment 

 CCCXCVIII, in which the consumption of oxygen had dropped 

 from 550 cc. to 300 cc, for the same change in pressure; further- 

 more, meat kept in decompressed air did not smell nearly as bad 

 as the other. Finally, in Experiment CCCXCIX, at a third of an 

 atmosphere, the consumption of oxygen was exactly a third of 

 that at normal pressure. 



But these results are not very extraordinary; it has been known 

 for a long time that putrefaction does not take place in a vacuum, 

 and it was quite natural to think that it would become less active 

 in proportion as the air was more rarefied. 



The effects of increased oxygen tension were much more inter- 

 esting to study. 



The most salient fact shown me by the experiments is that in 

 air which is sufficiently compressed putrefaction does not take 

 place, that no disagreeable odor appears, and that the muscle keeps 

 its normal appearance, except its color; its microscopic structure is 

 not perceptibly altered (Exp. CCCXCIII and CCCCIV) . 



Almost all the experiments reported above present remarkable 

 examples of this fact. 



But that is not all; when the excess pressure is reduced, and 

 when sufficient precautions are taken to protect against germs 

 brought from outside, putrefaction does not appear; so that for 

 weeks, for months, meat in a fresh state can be kept at normal 

 pressure. I call particular attention to this point of view in the 

 experiments in which I cooked and ate meat kept thus .for 20 days 

 (Exp. CCCXCI) , or a month (Exp. CCCLXXXVIII) . 



To secure conclusive and constant results, the greatest precau- 

 tions in detail are necessary. I did not always take them at the 

 outset; whence there result, in certain of the preceding experi- 

 ments and in others on blood, milk, etc., apparent exceptions, which 

 I included nevertheless, because they are instructive. 



And so, in my first experiments, when I wished to preserve a 

 substance, after subjecting it to compression, I closed with a good 

 cork stopper the flask in which it was placed; this stopper was 

 pierced by a hole, and when I had withdrawn the flask from the 

 apparatus, I applied over this small orifice a drop of melted wax, 

 with which, moreover, I sealed the whole stopper. 



I soon found out that this precaution was insufficient. The 

 stoppers, even when new, well washed, and heated, too often con- 



