500 Prof. E. Bunsen on the Temperature of the 



following values, according to the temperature at which eac 1 

 estimation was conducted*: — 



AtO° 1-5202 



Between 1146° and 2558° . 1-2162 

 Between 2558° and 3033° . 1-1402 



In consequence of the decomposition of water-vapour, t 1 

 specific gravity of the mixture would be found to be : 



At 150° . . 0-6221. 

 At 1874° . . 0-4977 

 At 2024° . . 0-4666 



The discontinuous combustion of a uniform mixture of 

 combustible gas with oxygen belongs to a class of phenomena 

 which fall under a law pointed out by me in another place f, whic T 

 is expressed as follows : — 



That the quantities of compounds which, under favourable ci 

 cumstances, form simultaneously in a perfectly uniform gaseou 

 mixture, bear simple atomic relations to each other ; and that 

 these simple atomic relations undergo sudden alterations by 

 the gradual addition of a third body, which does not affect the 

 homogeneous nature of the mixture. 



In order to explain this law 7 more clearly, I here append some 

 of the observations on which it is based, and which have been 

 already published J, 



If a light is applied to a uniform mixture of hydrogen, car- 

 bonic oxide, and oxygen which contains less oxygen than is 

 necessary for the combustion of one of the other two gases, 

 three results are possible; viz., the oxygen may burn only with 

 the one, or only with the other, or with both together. Expe- 

 riment shows that both burn ; but it is also seen that the quan- 

 tities of the two gases present in excess which the oxygen selects 

 for combustion stand in a simple atomic relation to each other, 

 and that these quantities of gas united to the oxygen do not 

 regularly increase by gradual increase of one part of the mixture, 

 but by intervals they spring suddenly from one simple atomic 

 relation to another. The oxygen divides itself between the excess 

 of hydrogen and carbonic oxide in the proportion represented by 

 the following atomic numbers of the products of combustion : — 



2C0 2 CO 2 CO 2 CO 2 CO 2 CO 2 

 HO HO 2HO 3HO 4HO 5HO 



* When the effect produced by the slight deviation from Mariotte and 

 Gay-Lussac's laws is neglected, 

 f Liebig's Annalen, vol. Ixxxv. p. 137. 

 X Bunsen's ' Gasometry,' p. 256 &c. 



