366 Mr. R. H. M. Bosanquet on the Illuminating -power 

 The number thus obtained for benzene is 

 312(l--1592) = 262-4. 



For marsh-gas, y = 123(-25--184) = 8-2 (? real). 



It seems probable that the H.S.C. for CD. 3-6 may have 

 slightly lessened values. But if they have, they are very 

 slightly lessened. 1 first assumed that they would form a 

 geometrical series with the numbers belonging to CD. 1 and 

 2 ; but the numbers thus obtained give rise to a value for 

 benzene much too low according to rigorous evidence. The 

 assumption of the same H.S.C for all CD. except 1 leads to 

 admissible results. 



Coal-gas, 



Analysis of the Gas. 



(Gas Light and Coke, Chem. Journ. 1884, p. 193.) 



Illuminating-power ... 16 

 Hydrocarbons, C„H m . . . 4*41 



Average formula ju ' ' ' ..q^ 



Carbonic acid 



Oxygen 026 



Nitrogen 5' 95 



Hydrogen 47*99 



Carbonic oxide 3*75 



Marsh-gas 37'64 



Direct determination of Disillwninated- Gas point. 



The observed values for ethylene and the dis. gas mixtures 

 (3 experimental points) were embodied in the following 

 equation, substituting in which # = "1415, calculated from the 

 analysis, we obtain the theoretical CP. of the dis. gas point. 



// = 175-40*--088) 3 + 136-5(>--088). 



ethylene. 



Dis. gas. 



X. 



y obs. 



y calc. Error. 



100 







•5 



68-5 



68-5 



31-02 



68-98 



-2SQ-2 



28-40 



28-42 +-02 



13-41 



86-59 



•2092 



16-84 



16-85 +-01 







100 



•1415 





7*33 (theoretical) 



The absorption here will be mainly due to the hydrogen 

 present. It is not nearly enough to admit of representation 

 by u logarithmic curve. 



Theoretical values of?/ below about 10 appear to correspond 

 to observed zero values. 



