Drs. Christison and Turner on Oil and Coal Gas. 207 



stead of rendering the matter clearer, and receiving the confi- 

 dence of men of science and of the public, differed so widely 

 from what had been previously obtained in London and else- 

 where, that a necessity was generally felt for further and more 

 varied experiments, before a question in which such an im- 

 mense capital was involved throughout the kingdom, could be 

 held as definitively settled. 



The experiments relate, 1st, To the instruments employed 

 m the inquiry, and particularly the photometers of Leslie and 

 Rumford ; that of the latter was preferred, Mr. Leslie's being 

 found inapplicable, on account of its being affected by non-lu- 

 minous heat, and not expressing accurately the power of lights 

 differing in colour. 2ndly, To the circumstances which affect 

 the degree of light emitted by the gases during combustion, and 

 which lead to the discovery of the principles on which burners 

 ought to be constructed :— these circumstances are arrano-ed 

 under three heads, the length of the flame, the construction 

 of the burner, and the shape of the glass chimney. 3rdlv, The 

 relative Illuminating power of Oil and Coal Gas. 



The authors conclude the account of their experiments* by 

 stating that it was not originally their intention to make any 

 remarks on the relative advantages of the two gases in a ge- 

 neral point of view. But as the subject has lately led to a long 

 parliamentary investigation, and as very erroneous notions 

 prevail on some matters which have engaged a share of their 

 attention, they add that it may be well to notice it briefly. 



The question of the relative advantages of oil and coal gas re- 

 solves itself into two: The first regards their relative oeconomy ; 

 The second, their comparative utility. 



1. Before we can determine their relative oeconomy, it is re- 

 quisite to settle their average quality. Taking their specific 

 gravity as the ground of comparison, we apprehend that, in 

 small towns, where the cannel coal can be had at a low price, 

 coal gas companies may be able to manufacture a gas of the 

 density of 700. In larger cities, such as Glasgow and Edin- 

 burgh, where coal of every kind is dearer, and the cannel coal 

 cannot easily be procured in sufficient quantity, the average 



• While the jjhilosopheis of Edinburgh were engaged in these interest- 

 ing inquiries, a celebrated Committee in Westminster have had to decide 

 on the same subject. Here, the most practical and conclusive experiments 

 were not, as in the North, on the illunu'nating power of the gases, i)ut on 

 the power of motives on divers members of the conunittee. Thus, by a 

 judicious distribution of their shares to some, by making others Directors 

 with large salaries, and by lighting gratuitously the mansions of others, the 

 powerful combination of coal gas companies obtained a decision, not in- 

 deed that their gas was at ail equal to oil gas, but that, in the metropolis at 

 least, the latter should not be allowed to come in con)pctition with it. 



specific 



