26 



exhibited several forms of gas-regulator from IMr. Sugg, by the aid 

 of which the pressure under which the gas bums is maintained 

 perfectlj' uniform whatever the variation in the pressure of the 

 supply. 



The influence of shades was next considered, and it was 

 pointed out that a very large amount of light is sacrificed by their 

 ' use. The following table shows the per-centage of light cut off by 

 screens of different kinds of glass : — 



Clear 12 



Slightly ground in pattern ... ... ... 24 



Half ground ... ... ... 35 



All ground 40 



Opal 60 



The object of a shade is to maintain a steady flame and to 

 prevent undue access of cold air. The bad effect of the bell-shaped 

 shade, not unfrequently used, was alluded to ; this form of shade was 

 condemned by the Lecturer as worse than useless ; and he questioned 

 whether, under ordinary circumstances, it would not be better to 

 dispense with shades. 



Lastly, the means of increasing the illuminating power of ordi- 

 nary coal gas were briefly alluded to, and the so-called albo-carbon 

 burner was exhibited. In this burner, the gas before it is burnt is 

 saturated with naphthalene vapour, and thus has its illuminating 

 power very much increased. Some economy results from its use, 

 as a good light is secured by the expenditure of considerably less 

 gas than is ordinarily burnt, and although the burner in its present 

 form has some serious disadvantages, the invention is an important 

 one. There is an increasing tendency at the present time to employ 

 gas as a fuel, but before this can be done at all universally the 

 price of gas must be considerably lowered. If it were possible to 

 supply gas for heating purposes alone and to render it illuminating 

 where required by naphthalising, or some similar means, this result 

 could be achieved far more readily than it ever can be so long 

 as it is necessary to furnish illuminating gas to the consumer. The 

 gi-eater the heating power of the gas, the better suited it would be 

 for napthalising. 



