The other was introduced into a jar of pure hydrogene through water. He immediately began to struggle very much, and in a quarter of a minute fell on his side. On feeling the thorax, the pulsations of the heart appeared very quick and feeble, they gradually diminished; his breathing became momentarily shorter, and in rather more than three quarters of a minute, he was taken out dead. Dr. Kinglake was present at this experiment, and afterwards dissected both of the animals.
b. Of two similar rabbits of the same breed, nearly three months old. One was introduced into nitrous oxide, and after being rendered senseless by the respiration of it for nearly a minute and half, was exposed to the atmosphere, before a warm fire. He recovered gradually, but was occasionally convulsed, and had a paralysis of one of his hinder legs for some minutes: in an hour he was able to walk. The other, after being immerged in hydrogene for near half a minute, was restored to the atmosphere apparently inanimate. In less than a minute he began to breathe, and to utter a feeble noise; in two minutes was able to walk, and in less than three minutes appeared perfectly recovered.
c. A kitten of about two months old, was introduced into a jar of nitrous oxide, at the same time that another of the same breed was plunged under a jar of water. They both struggled very much. The animal in the nitrous oxide fell senseless before that under water had ceased to struggle, and to throw out air from its lungs. In two minutes and three quarters, the animal under water was quite dead: it was taken out and exposed to heat and air, but did not shew the slightest signs of life. At the end of three minutes and half, the animal in nitrous oxide began to gasp, breathing very slowly; at four minutes and three quarters it was yet alive; at the end of five minutes and quarter it appeared perfectly dead. It was taken out, and did not recover.
From these experiments it was evident, that animals lived at least twice as long in nitrous oxide as in hydrogene or water. Consequently from this circumstance alone, there was every reason to suppose that their death in nitrous oxide could not depend on the simple privation of atmospheric air; but that it was owing to some peculiar changes effected in the blood by the gas.
IV. Of the changes effected in the Organisation of
warm-blooded Animals, by the respiration
of Nitrous Oxide.
The external appearance of animals that have been destroyed in nitrous oxide, is very little different from that of those killed by privation of atmospheric air. The fauces and tongue appear of a dark red, and the eyes are dull, and a little protruded. Their internal organs, however, exhibit a very peculiar change. The lungs are pale brown red, and covered here and there with purple spots; the liver is of a very bright red, and the muscular fibre in general dark. Both the auricles and ventricles of the heart are filled with blood. The auricles contract for minutes after the death of the animal. The blood in the left ventricle, and the aorta, is of a tinge between purple and red, whilst that in the right ventricle is of a dark color, rather more purple than the venous blood. But these appearances, and their causes, will be better understood after the following comparative observations are read.
a. Of two similar rabbits, about eight months old, one A, was killed by exposure for near six minutes to nitrous oxide, the other, B, was destroyed by a blow on the head.
They were both opened as speedily as possible. The lungs of B were pale, and uniform in their appearance; this organ in A was redder, and every where marked with purple spots. The liver of A was of a dark and bright red, that of B of a pale red brown. The diaphragm of B, when cut, was strongly irritable; that of A rather darker, and scarce at all contractile. All the cavities of the heart contracted for more than 50 minutes in B. The auricles contracted for near 25 minutes with force and velocity in A: but the ventricles were almost inactive. The vena cava, and the right auricle, in A, were filled with blood, apparently a shade darker than in B. The blood in the left auricle, and the aorta, appeared in A of a purple, a shade brighter than that of the venous blood. In the left auricle of B it was red.
I opened the head of each, but not without injuring the brains, so that I was unable to make any accurate comparison. The color of the brain in A appeared rather darker than in B.
b. Two rabbits, C and D, were destroyed, C by immersion in nitrous oxide, D in hydrogene: they were both dissected by Dr. Kinglake. The blood in the pulmonary vein and the left auricle of C was of a different tinge, from that in D more inclined to purple red. The membrane of the lungs in C was covered with purple spots, that of D was pale and uniform in its appearance. The brain in C was rather darker than in D; but there was no perceptible effusion of blood into the ventricles either in D or C. The liver in C was of a brighter red than in health, that in D rather paler.