234 HISTORY OF SCIENCE. 



most remarkable made during the seventeenth century. He showed 

 that nitre, a substance which had been the theme of endless discussions, 

 was composed of an acid and an alkali, and that it contained a spirit 

 (or gas) capable of actively supporting combustion ; that antimony was 

 capable of fixing this gas, and was thereby increased in weight. He 

 proved that flame is maintained at the expense of something in the air, 

 and that the same matter which maintains combustion in air enters into 

 the composition of nitre as its most active ingredient ; for a mixture 

 of sulphur and nitre may be inflammable in a vacuum, giving the same 

 products as sulphur inflamed in air. Mayow shows that the " nitro- 

 aerian spirit " is the air which maintains combustion, by inverting a 

 bell-jar over a lighted candle floating on the surface of the water within 

 the jar. The water will rise within the jar as the candle removes the 

 *' nitro-aerian " particles. The same result was obtained in similar ex- 

 periments, in which other inflammable bodies, such as camphor, sul- 

 phur, etc., were ignited within the jar by concentrating on them the 

 sun's rays by means of a lens or burning-glass. He observes, that after 

 the flame goes out, it is impossible to rekindle it. He confined a 

 mouse in a vessel covered by a piece of moist bladder, and after a few 

 minutes the bladder bulged inwards, showing that something was being 

 removed from the air ; and, in fact, when a mouse or other animal was 

 suspended in a cage within a bell-jar inverted over water, he saw the 

 water rise above the outside level, just as in the case of the burning 

 candle. He found, also, that in each case the bulk of the air was 

 diminished by about one-fourteenth. The air in which a candle had 

 been extinguished was incapable of supporting life in an animal, and 

 air which had been exhausted by respiration extinguished the flame of 

 a candle. The conclusion drawn from these experiments is that the air 

 loses some of its elastic force by the respiration of animals, as it does also 

 by combustion; and animals remove from it particles of the same nature 

 as flame removes. 



Mayow found that respiration changed the dark colour of venous 

 blood into the bright red colour of arterial blood, and he compares 

 respiration to fermentation in so far as in each there is an absorption 

 of the igno-cerian particles. Nor does he hesitate to attribute animal 

 warmth to this absorption. 



The experiment of producing and collecting hydrogen, which we 

 have seen had been performed by Boyle, was repeated by Mayow with 

 nitric acid, and, strangely enough, without his observing its inflamma- 

 bility or other properties by which it differs from air. The experiment 

 is described as one to determine whether air can be generated de novo. 

 Mayow found that the aeriform body he had collected was permanent; 

 it could not be reduced to a liquid by any cold he could apply. He 

 says, however, that although this substance has the same appearance 

 and elasticity as air, it is hard to believe that it is really such. We 

 see here a little progress, inasmuch as Mayow doubts whether the 



