442 Historical 



they began to pine, in two hours more they were sick, and three 

 hours afterwards they died. 



I also placed a duck in a receiver, in which I made the air three 

 times denser than that of the atmosphere; however it remained gay 

 for an hour, and seemed to have suffered no inconvenience. 



I next shut in three perches and a trout with a great quantity of 

 water together with some living earthworms; I made the air in the 

 receiver three times denser; prolonging the experiment for six hours 

 I observed the following things: the first hour all the little fishes 

 swam very well, often took new air at the surface of the water, and 

 yet did not eat any worms; after an hour, the trout seemed less 

 lively, and was more quiet; half an hour afterwards it shook its 

 fins, yet its back was turned upwards as in the natural state; the 

 perches during this time were swimming gayly; five hours afterwards, 

 the trout, still having its back turned upward and resting freety in 

 the water, had died; one perch became more quiet; after the sixth 

 hour, it also was near death, but was lying on the bottom with its 

 back turned upward; then after I had opened the vessel and let the 

 air out, the two perches were alive and very gay; but the two dead 

 fish were floating lying on their backs; the worms all this time had 

 lived under water, and being taken from it, they were quite sickly. 

 This experiment was made November 10, 1730. 



I call attention to the interesting conclusions which Musschen- 

 broeck draws from the experiments which he has just reported: 



It follows from these experiments that animals can live longer in 

 compressed air than in natural air without its being renewed; for 

 although the enclosed animals consume a little air, a portion of its 

 elasticity is lessened; nevertheless, in compressed air there is enough 

 air left, and the elasticity is great enough: so that in the inspiration 

 the vesicles of the lungs expand well and easily, and the blood circu- 

 lates very freely in the arteries and the veins of the lungs. However, 

 animals finally die in this compressed air; but what is the cause of 

 that? It is not the lack of air, it is not the loss of its elasticity; :Cor 

 the mercury shows by the index that there is still enough of it left. 

 But they die because the exhalations from the body of the animal 

 are harmful to its lungs, or to its life, or because something is con- 

 sumed out of the air which is necessary to the maintenance of life, 

 and which must be constantly mingled with the blood. This last idea, 

 however, can hardly be well founded, because the celebrated M. 

 Boerhave has proved by irrefutable arguments that no air inspired 

 into the lungs can pass from the vesicles into the blood vessels: that 

 is why we must conclude that the particles which we exhale are 

 harmful to us, and that those which issue from other animals are also 

 harmful to them and act like a poison; and so we understand why 

 divers shut up in a bell, a cask, or other vessel must always be 

 refreshed with new air so that they may breathe comfortably; and 

 why miners who work in deep mines are very uneasy if new air is 

 not constantly sent them in the mines by means of blowers or some 

 other ventilators. (P. 58.) 



