ON THE DEVELOPMENT OF LIGHT FROM COAL-GAS. 10ft 



made by saturating air with petroleum spirit, requires to be burned at a> 

 pressure not exceeding '1 of an inch, which can be obtained only with an- 

 Argand with very large holes, or a batwing of peculiar construction, 

 called the " American Regulating Batwing." At ordinary pressures, such 

 as are used for coal-gas, there is scarcely any light, and the flame keeps 

 about a quarter of an inch or more above the burner. 



It is not only on the score of economy that it is desirable to burn gas- 

 in such a manner as to afford the greatest possible amount of light. The 

 burning of a moderate sized jet of gas produces as much carbonic an- 

 hydride as the breathing of two grown-up men, and as, in an ordinary 

 apartment, we have usually from three to six of these, the air becomes 

 vitiated with remarkable rapidity. It is therefore desirable, in relation to 

 health, to obtain the illumination we require with the least possible ex- 

 penditure of gas. The sulphur in gas is a very serious drawback to its 

 use. In burning it is, no doubt, converted chiefly, if not entirely, into 

 sulphurous anhydride ; but it is soon converted into sulphuric acid, which 

 attacks with avidity all the more readily destructible articles in the apart- 

 ment. So far back as forty years since the effects of the sulphuric acid 

 arising from the combustion of gas upon the binding of books and many 

 articles of furniture was noted, and recent experiments have shown that 

 leather, paper, &c, in ill-ventilated apartments exposed to the emanations 

 from burning gas for a series of years contain very large quantities of sul- 

 phuric acid. One of us has had occasion recently to investigate the action 

 of burning gas upon cotton goods stored in warehouses in London, Manches- 

 ter, and other cities and towns, and found that, in some cases, a few 

 months are sufficient to affect certain colours ; while within a year enough 

 sulphuric acid is absorbed to seriously injure the strength of the fabrics. 

 No doubt the true remedy for this evil is to ventilate the warehouses ; but 

 it is obvious that if the gas were burned in an advantageous manner, and 

 the quantity reduced to one-half or one-third, the damaging effects would 

 be proportionately lessened. 



There are several distinct qualities of gas in use in this country. The 

 best may be described as Scotch cannel-gas, as it is made only in Scot- 

 land, where the illuminating power varies from 2-1 to 30 standard for 5 

 cubic feet per hour, consumed in a union or fishtail jet ; the average may 

 be fairly stated as 26 candles. In London a cannel-gas is used in small 

 proportion, the illuminating power of which is about 23 candles ; and in 

 Liverpool, Manchester, Carlisle, and probably some other towns, an inter- 

 mediate gas is manufactured, the illuminating power of which is about 20 

 candles. The common gas in London and most other English and Irish 

 towns has an illuminating power of 14 to 16 candles. In the present 

 Report it is our intention to confine our investigations to two qualities of 

 gas, i.e., cannel-gas of 26 candles, and common gas of 16 candles illumi- 

 nating power. The photometric results in each case will be calculated 

 to these standards, although in the actual experiments the gas may have 

 been a little higher or lower in quality. In the case of cannel-gas the 

 standard is found by testing the gas by a union jet consuming 5 cubic 

 feet at a pressure of "5 of an inch ; while the common gas is tested by 

 Sugg's London Argand, consuming 5 cubic feet per hour at a pressure of 

 about - 05 of an inch. The best means at present known of burning each 

 quality of gas will be pointed out, and tabulated results will be given, 

 containing the details of the testings of the different kinds of burners 

 under varying conditions of pressure. 



