204 Historical 



on it, tends to escape entirely. Hence M. Mariotte has conjectured 

 that if one was at an elevation where the weight of the atmosphere 

 was diminished by half, the blood, much warmer than lukewarm 

 water and still full of air, would boil, so that it could no longer circu- 

 late, and we must admit that the conjecture was well founded. How- 

 ever, MM. Cassini and Maraldi, who have ascended to altitudes where, 

 according to their calculation, the weight of the atmosphere was 

 almost a half less, felt no distress caused by the rarefaction of the air. 

 Many persons who have been still higher felt no more than they. 



I do not need to go to great lengths to show the mistake of 

 the writer in regard to the height of the mountains which Cas- 

 sini and Maraldi ascended. A few lines above, he said himself 

 that "the barometer hardly drops 5 or 6 inches on the highest 

 mountains where observations have been made". 



Later, the Italian physicists once more took up the study of 

 these important problems. Veratti, an academician of Bologna, 

 made numerous experiments 11 on this subject. He begins by re- 

 calling that two very different explanations have been given for 

 the death of animals in the vacuum: 



According to the clever Borelli, this death occurs because, when 

 the outer air is removed, the air contained in the blood and the humors 

 is greatly rarefied and distends the vessels beyond the endurance of 

 the animal. According to this idea we must conclude that in the blood 

 and the other liquids a sort of effervescence is caused which rarefies 

 them and slows their movement, that the nerves are compressed by 

 it and the course of the animal spirits checked, which necessarily 

 brings on the death of the animal .... 



M. Musschenbroeck . . . thinks that the cause of this phenomenon 

 lies in the lungs. He thinks that the pulmonary vesicles, when they 

 receive no more outer air, contract more than is natural .... which 

 causes the vessels to be cramped and the blood to be stopped in them 

 .... (See above the opinion of Musschenbroeck and that of Guideus.) 



Veratti, having placed quails in the vacuum, found that their 

 lungs floated after death. The lungs of rats and rabbits floated 

 also, but those of kittens a week old did not. He concludes from 

 this: 



That Musschenbroeck and Guideus had either used in their experi- 

 ment new-born animals, in which the oval hole was not yet closed, 

 and whose lungs could not expand sufficiently to become specifically 

 lighter than water; .... or that they left the animals in the vacuum 

 for too long a time after their death; .... or that the air in the 

 receiver was perhaps more rarefied in the experiments of these physi- 

 cists .... who were not careful about specifying the degree of 

 rarefaction which they used .... As for him, he merely rarefied the 

 air to the point necessary to kill the animals .... 



The lungs, he says in conclusion, are heavier than water only in 



