5€6 Letter of Spallavzani to C. Senehler 



worm?, insects, fishes, amphibia; and in warm-blooded 

 aninials, I mean birds and mammalia, this destruction in a 

 given proportion of common air is complete, at least as far 

 as can be shown by Kunckel's phosphorus. 



In speaking of mammalia, I made, on purpose, several ex- 

 periments on certain parts of their bodies, such as the 

 iTiusclcs, tendons, bones, brain, fat, blood, and bile. Each of 

 these parts destroys the oxygen gas in different proportions, 

 except the bile, which appears to be incapable of that 

 operation; but the blood is not the only one of the animal 

 parts most proper for the destruction of oxygen gas ; though 

 1 firi^t believed that, in this respect, it was superior to them 

 ail, jutlging from what has been written on the blood in re- 

 gard to the decomposition of the air. The blood of cold 

 and warm-blooded animals, the venous as well as the ar- 

 terial, have been subjected to experiment, and I had no va- 

 riation in the res'.ilts. 



In the beginning of this letter I expressed my doubts on 

 the consumption of oxygen gas, occasioned by worms shut 

 up in common air : Is it produced by the absorption of its 

 base, or rather by its combination with the carbon which is 

 exhaled from these animals ? I found the carbonic acid in the 

 vessels contained in these animals, and this carbonic acid 

 must have some source, since the vessels are full of it; but 

 this doubt was removed by showing the appearance of this 

 gas, though the worms were confined in azotic and hydrogen 

 gas. I observed the same thing in the five other classes of 

 animals ; so that I think myself authorized to assert, from 

 the fact in the experiment with oxygen gas, that this gas 

 abandons its base to the cutaneous organ of the animals, 

 which absorb it as well as the different parts of their 

 bodies. 



But you will perhaps ask, Whether the azotic gas of the 

 atmosphere suffers any chemical alterations in so great a 

 multiplicity of experiments ? — I shall observe in answer, 

 that 1 never made any without considering this gas, and 

 without finding that, according to the varieties of the ani- 

 mals, it sometimes remained untouched, and at others ex- 

 perienced some diminution; but that it was always very 

 small in comparison with that of the oxygen gas, though 

 the latter is scarcely equal to a fourth of the former m 

 common air. 



I then saw that the chief direction of this animal absorb- 

 ing force is to take away and appropriate to itself oxvgen : 

 it has a direct relation with the temperature of the atmo- 

 jpherCj so that it may almost be established as a general rule, 



that 



