354 
especially with, atmospheres rich in oxygen, hy an ammoniacal copper 
solution and then hy hydrogen explosion. Oppenheir* says . * 
exploding with hydrogen, it is necessary to have six times as much 
hydrogen as oxygen present as otherwise there will he oxides of 
nitrogen formed. In determining hydrogen in his artificial atmos¬ 
pheres in the small respiration apparatus, Oppenheim« found that 
the determination of hydrogen hy explosion was always affected hy 
the fact that he must have an excess of oxygen and under these condi¬ 
tions some nitrogen is burned with the oxygen hut if there is an 
excess of hydrogen, there is no trouble. 
Zuntz respiration apparatus for animals.—while a mouthpiece or 
mask is usually out of the question when experimenting with dogs, 
Zuntz has been most fortunate in making a large number of tracheal 
fistulas with both dogs and horses. A dog which has been in the 
laboratory for a number of years and fully accustomed to experiments 
1ZO 
of this nature is shown connected with the apparatus in Figs. M#- 
ill 
and The connection with the valve pieces is made by inserting 
a rubber tube containing an inflatable rubber gasket. This makes 
an absolutely tight joint with the silver tube in the trachea. At 
the first moment of inserting this tube, there is irritation but 
almost immediately, the dog lies quietly and he has been trained to 
lie in the characteristic position shown in the two figures for the 
length of time necessary to conduct an experiment. A very singular 
I 
fact is that many of these dogs have had these tracheal fistulas and 
lived in the laboratory as long as six years and remarkably enough, 
two of these dogs died with carcinoma of the intestine. A number 
of fistulas hare also been made on horses and after the experiments 
are over, the fistulas have hea led in 14 days and the animals have