CHEMISTRY. 173 



and, being conducted in a fine stream to the rear end of the re- 

 torts, enters in company with a certain amount of water 

 which, when it reaches the retorts, is in the state of superheated 

 steam. There results from the tar and the superheated steam a 

 mixture of hydrocarbons and carbonic oxide, which go forward to 

 increase the amount of gas. Retorts of a peculiar construction 

 are employed. 



Enrichment of Gas. In view of the difficulty of obtaining bog- 

 head cannel and other coals suitable for the enrichment of gas, 

 considerable use is being made of bitumen from the Island of 

 Trinidad, where there exists a supply practically inexhaustible. 

 This bitumen is used by the Brooklyn (N. Y.) Gas Company and 

 gives full satisfaction. Amer. Oas-Liglit Jour. 



Use of Sulphuric Acid in Coal-Gas Purification. Mr. M. C. 

 Pelonze publishes an article in the "Journal of Gas Lighting," on 

 the use of sulphuric acid for the removal of ammonia from coal- 

 gas, and states that, heretofore, the sulphuric acid was improperly 

 applied, either diluted in scrubbers or more concentrated in 

 purifying-boxes. In both cases the gas takes up some of the acid, 

 and thus deteriorates the pipes and burners. Pelouze besprinkles 

 his purifying material (oxide of iron or sawdust) with water con- 

 taining 20 per cent, sulphuric acid of 53B. (spec. gray. 1.53). 

 The material is then exposed to the air in a warm place until 

 sufficiently dried, and is then used. After use sulphuric acid must 

 be added to replace that which was neutralized by the ammonia. 

 When the salt of sulphate of ammonium has accumulated it may 

 be washed out with water, and the solution worked up. Pelouze 

 states that this method also prevents the separation of naphtha- 

 line. Amer. Chemist . 



Reagent for Detecting Ammonia in Illuminating Gas. M. Meu- 

 nier prepares a tincture of the fresh leaves of the Colcus Ver- 

 sclwftelti by treating these leaves with absolute alcohol to which a 

 fe\v drops of sulphuric acid have been added. Slips of Swedish 

 filter-paper dyed with this tincture and dried in the open air 

 furnish a valuable test for the presence of ammonia, being turned 

 green by alkalies. The presence of ammonia in coal gas may be 

 ascertained by holding one of the moistened strips for a *few 

 moments in a current of the gas. The paper should be preserved 

 in well-stoppered bottles. Cosmos. 



Determination of Sulphur in Coal Gas. Vernon Harcourt's 

 method is as follows: "In my apparatus I use a small Bun- 

 sen burner, which gives a flame, scarcely visible in the daj'light, 

 of three-quarters of an inch in length, when burning at the rate of 

 a quarter of a cubic foot per hour. The gas is supplied by 

 means of an aspirator with between 20 and 30 times its volume 

 of air. A funnel placed at the top of the cylinder in which the 

 gas burns admits the air through holes in the neck, and dis- 

 tributes it down the sides of the cylinder, while the products of 

 combustion and the excess of heated air are withdrawn from 

 within the funnel through a tube rising from the bottom of the 

 cylinder. This tube fits loosely into another tube, which passes 

 through an India-rubber plug closing the cylinder, and is attached 



