214 ANNUAL KECORD OF SCIENCE AND INDUSTRY. 



which is supposed to give up its extra oxygen atom with 

 great readiness. For this purpose they passed the pure mon- 

 oxide through potassium hydrate and lime-water into a flask. 

 Into the same flask oxygen was passed after treatment with 

 potassium hydrate and lime-water, and also after being ozo- 

 nized. The interior of the flask was moistened. From the 

 flask a third tube led the products first through lime-water 

 and then over potassium hydrate. But, though the currents 

 of gas were slow and the action was long continued, not a 

 trace of dioxide was formed, even when the experiment was 

 repeated in direct sunlight. This result is the more supris- 

 ins: from the readiness with which carbonic oxide is oxidized 

 by chromic acid solution. The authors propose to study the 

 action of hydrogen peroxide on this substance. 4 D, III., xi., 

 February, 1876, 136. 



ox THE HYDROCARBONS OF COAL GAS. 



Berthelot has made a somewhat exhaustive investigation 

 of the hydrocarbons existing in coal gas, the results of whicli 

 go to confirm his theory of the action of acetylene and hy- 

 drogen at high temperatures. In the gas which is supplied 

 to the city of Paris he finds that benzene may be detected 

 very readily in so small a quantity as two or three cubic cen- 

 timeters by exposing in it a drop of fuming nitric acid. On 

 diluting the drop with water, the peculiar almond odor of 

 nitrobenzene is at once recognized. If fifty liters of the gas 

 be passed through 8 or 10 c. c. of the acid, enough nitroben- 

 zene separates on dilution to weigh ; and from the amount 

 thus obtained it appears that this gas contained two or three 

 volumes of benzene vapor in the hundred. More accurately, 

 the amount present is from 3 to 3.5 volumes. Next to marsh 

 gas, therefore, benzene is the principal hydrocarbon in coal 

 gas, and is the substance to which the gas mainly owes its 

 illuminating power. Besides benzene, the gas contains ethy- 

 lene, propylene, and butylene of the olefine series, and acety- 

 lene, allylene, and crotonylene of the acetylene series. These 

 bodies were detected by absorbing them with concentrated 

 sulphuric acid, diluting, and then fractioning. In one million 

 volumes of the Paris gas, the author concludes that there are 

 by this analysis : Benzene in vapor, 30,000 to 35,000 volumes; 

 acetylene, 1000 (about); ethylene, 1000 to 2000; propylene, 



