1903.] 



Benzene in Poisoning by Coal Gas. 



81 



movements. By 11.55 it had recovered sufficiently to show both these phenomena, 

 and at 1.30 it -was so far recovered that it could recover its position when turned 

 on its back, and in a couple of hours later was apparently normal. 



II. In a second experiment the arrangements were the same as in the first, 

 except that in C the gas which had passed through the oil was allowed to pass 

 through water saturated with benzene instead of through pure benzene. In this 

 case the phenomena in A and C were practically identical, and were similar to 

 those observed in A in the first experiment. We need not, therefore, give fuller 

 details of this experiment. 



We thus see that, when frogs are exposed to coal gas, motor 

 phenomena are produced, which are absent if the coal gas be pre- 

 viously purified by passage through oil, and that these phenomena 

 can be reproduced if the purified gas be made to take up benzene 

 vapour. The poisonous properties of the gas can be increased by 

 increasing the tension of the benzene vapour. We are, therefore, 

 justified in concluding that the differences between the effects of 

 CO and coal gas observed by Kunkel and Vahlen, depend on the 

 presence in the latter of benzene. The slight motor excitation 

 observed in frogs in coal gas, which had been purified by passage 

 through oil, is exactly similar to that described by Kunkel, as the 

 result of deprivation of oxygen, produced by placing the frogs in 

 nitrogen or CO, as is shown by the following experiment : — 



III. Two frogs were placed, one in a bell jar through which CO gas was led, the 

 other in a similar jar through which coal gas was led after passing through oil. 

 Both animals in a short time showed slight twitchings of isolated groups of 

 muscles in the extremities and back, and occasional extensor movements of the 

 hind limbs, which gradually diminished. No difference was observable between 

 the two frogs. In three quarters of an hour they were taken out of the jars, and 

 both recovered within a short time. 



In order to be certain of the part played by benzene in coal gas 

 poisoning, we must have some idea of the effect of pure benzene on the 

 frogs. I have been unable to find any published experiments over the 

 effects of inhalation of benzene on the frog. Beyer* states that xylol 

 acts as a narcotic poison, like the other odorous substances investigated 

 by him. I have, therefore, made some experiments on the influence 

 of benzene vapour in the presence of oxygen on frogs. 



IV. A frog was placed in a bell jar, in which a beaker of benzene was hung up. 

 Eight minutes after the beginning of the experiment spasmodic movements and 

 twitchings began in various parts of the body, accompanied by a considerable 

 secretion of mucus. After a few minutes the spasms ceased, the frog lay still 

 with extended limbs, and respiration, which at first was irregular, became 

 gradually shallower and less frequent. Twenty minutes after the beginning of the 

 experiment all respiratory and other movements had ceased. The frog was taken 

 out of the jar, and recovered in a few hours. 



* Beyer, " Narkotische Wirkungen von Eiechstoffen und ihr Einfluss auf die 

 oaotorischen Nerven des Frosches." ' Archiv fur Anatomie und Physiologic, 

 phvsiologische Abteilung,' 1902, p. 201. 



VOL. LXXIII. G 



