110 Prof. S. U. Pickering on the Determination 



in which the value of r, as deduced from the equation 

 (C, 2H 2 ) = 4r=2(H 2 , i0 2 ) +/• Ci-(CH 4 , 20 2 ) 

 = 2x68360 +/.C 1 -211930, 

 may be substituted, thus giving 



3x 68360 + 2/. 0^370440=3 x 68360 + %£>■ - 3 X 2 ™ +v > 

 whence 



, 1 = /^_3 70 440 + 3x ™ ; . . (III.) 



and, by combining this equation with (I.), we get the differ- 

 ence between the values of v 2 and t> l5 independent of the 

 value of/. C l7 or of any quantities other than those deter- 

 mined experimentally, 



2^-^ = 13920. 

 Similar results are obtainable with v B . 



Now, adopting Professor Armstrong's view that Thomsen^s 

 value for/. G 1 should be increased by some unknown quantity, 



x, it will follow that the value for r will become r+ -, while 



x 

 those for v 1; v 2j and v s will be converted into v x + ^? v 2 + x, 



(jX 



and v 3 + -~- respectively ; or 



Vl = 14056 + |, 



v 2 = 14250' + *, 



Sx 



v 3 = -81 + y 



The importance of these values can scarcely be overrated. 

 If, as seems very probable, x represents some number con- 

 siderably larger than 14000 cal., the heat evolved in the union 

 of two carbon atoms will be very nearly, though not quite, 

 proportional to the number of bonds by which they are united; 

 a view which, I think, must be admitted to be highly probable. 

 We at once obviate the necessity for denying that carbon atoms 

 can be joined by anything but single bonds, and that com- 

 pounds containing trebly-bound carbon atoms are not really 

 compounds at all ; while the slight loss of energy entailed in 

 substituting a double bond for two single ones, and a treble 

 bond for a double and single one, gives an explanation of 

 the relative instability of unsaturated hydrocarbons. Thorn- 

 sen's conclusions tend to entirely destroy the bond theory ; 



* 14056x2—14250 gives 13862, instead of 13920 as above, owing to its 

 being deduced from mean, instead of special results. 



