246 ANNUAL OF SCIENTIFIC DISCOVERY. 



Notwithstanding the great economy and convenience attending the use 

 of gas, and, in a sanatory point of view, the high position which, as an 

 illuminating agent, coal gas of proper composition occupies, its use in 

 dwelling houses is still extensively objected to. The objections are partly 

 well founded and partly groundless. As is evident from the foregoing 

 table, even the worst London gases produce, for a given amount of light, 

 less carbonic acid and heat than either lamps or candles. But then, where 

 gas is used, the consumer is never satisfied with a light equal in brilliancy 

 only to that of lamps or candles ; and consequently, when three or four 

 times the amount of light is produced from a gas of bad composition, the 

 heat and atmospheric deterioration greatly exceed the corresponding effects 

 produced by the other means of illumination. By using a gas, however, 

 of nearly the normal composition, such as the hydrocarbon gases above 

 named, it is evident that three or four times the light may be employed, 

 with the production of no greater heat or atmospheric deterioration than 

 that caused by wax candles or the best constructed oil lamps. But there 

 is nevertheless a real objection to the employment of gaslight in apart- 

 ments, founded upon the production of sulphurous acid during its com- 

 bustion : this sulphurous acid is derived from bisulphuret of carbon, and 

 the organic sulphur compounds, which have already been referred to as 

 incapable of removal from the gas by the present methods of purification. 

 The formation of sulphurous acid can readily be proved, and even its 

 amount estimated, by passing the products of combustion of a jet of gas 

 through a small Liebig's condenser ; the condensed product being heated to 

 boiling with the addition of a few drops of nitric acid, and then treated with 

 solution of chloride of barium, yields a white precipitate of sulphate of 

 barytes if any sulphur compound be present in the gas. These impuri- 

 ties, which are encountered in almost all coal gas now used, are the prin- 

 cipal if not the only source of the unpleasant symptoms experienced by 

 many sensitive persons in rooms lighted with gas. 



GAS AND GAS FIXTURES. 



From a report recently made to the Directors of the Boston Gas Com- 

 pany, by Dr. A. A. Hayes, in answer to certain questions propounded, 

 we make the following extracts. They will be found to imbody informa- 

 tion of value to all gas companies and consumers, wherever located : 

 1st. " On the value, purity and illuminating power of the Boston gas." 

 The value of purified gas depends on its illuminating power, determined 

 by the light which a given volume will afford, as compared at the moment 

 with that from some well-known source. By common consent, the stan- 

 dard adopted is a spermaceti candle consuming 120 grains per hour ; and 

 with such a standard the volume of five cubic feet of gas consumed in one 

 hour from an argand burner is compared by photometric instruments. 

 In the language of the gas engineers, five cubic feet of a gas affording 

 the same light as thirteen sperm candles, burning 120x13=1560 grains of 

 sperm per hour, is called thirteen candle gas. 



