Sudden Changes in Pressure 859 



Subchapter III 



EFFECT OF SUDDEN DECREASE OF PRESSURE 

 BEGINNING WITH SEVERAL ATMOSPHERES 



The subject of our researches here becomes much more interest- 

 ing. Indeed, it draws nearer the phenomena which we mentioned 

 in the historical part, in speaking of laborers who work on the 

 piers of bridges and of divers in suits. 



I shall begin, as usual, by a detailed account of a certain number 

 of experiments. I report first those in which the decompression 

 was made without interruption and as rapidly as possible. 



1. Decompression without Interruption. 



A. Experiments Made on Sparrows. 



Experiment DV. July 20. House sparrow. Seltzer water receiver. 

 Brought in 20 minutes to 8 atmospheres; left for 5 minutes under 

 pressure. Opened the large cock first, and made the decompression 

 in a few seconds. Struggled at the moment of decompression, then 

 did not appear sick, and survived. 



Experiment DVI. August 3. House sparrow. Same apparatus. 

 Taken to 8 atmospheres at 12:30. 



At 2 o'clock, sick; at 2:45, very sick. Took a sample of air which 

 contained 2.1% of CO.. Tension: 2.1 x 8 = 16.8. 



Opened the large cock suddenly; the bird fell backward violently; 

 rose immediately: its rectal temperature was 25°, that of the outer 

 air being 20°, blood of the jugular veins very red; no gas seen. Re- 

 mained on its back and died in 10 minutes. At death, the venous 

 blood is dark; bubbles of gas seen in the jugulars. 



Experiment DVII. May 1. House sparrow. Glass cylindrical re- 

 ceiver . 



2:05, raised to 10 atmospheres; surrounded by papers wet in 

 potash solution so that the C0 2 is absorbed as it is produced. 



At 3:40, the bird appears dead; the pressure is 9Vz atmospheres; 

 the air contains 14.1% of oxygen, and no doubt very little carbonic 

 acid. Decompression made rapidly. Almost immediately, the bird, 

 which raised its head at the moment when the cock was opened, 

 became very lively; bloody suffusions on the cranium. Survived. 



Experiment DVIII. May 10. House sparrow. Cylindrical appara- 

 tus. 



From 4:15 to 4:20, raised to 16 atmospheres. After 5 or 6 min- 

 utes shows quiverings with great distress, slight convulsions, etc. 

 characteristic of poisoning by oxygen, the tension of which was 

 16 x 20.9 = 334. At 4:30, decompression made in 1 minute; did not 



