ATOMIC WEIGHTS 59 



These figures are interesting for comparison with those previously dis- 

 cussed, but can hardly be used in a general combination. 



Another group of data from which the carbon-oxygen ratio can be 

 deduced is found in the density determinations of certain organic com- 

 pounds. The older measurements need not be considered, but two recent 

 investigations have some real value. 



First, the density of methyl oxide (0113)20, as determined by Baume.* 

 Two series are given, with the subjoined values for the weight of a normal 

 litre : 



I. n. 



2.10912 2.10925 



2,10886 2.10941 



2.11045 2.11026 



2.10920 2.10936 



2.10948 2.11005 



2.11003 2.10977 



2.10947 



Mean, 2.10968, ± .00011 



Mean, 2.10951, ± .00014. 



A small correction raises these means by 0.00001. Oombined, the 

 final value is 2.10961, ±.000084. With the critical data given by Baume, 

 ao = 0.03111, and &o = 0.00382. Applying these figures by means of the 

 formula already cited, and assigning to the weight of oxygen the probable 

 error found from Morley's observations, the molecular weight of methyl 

 oxide becomes 46.0306, ±.0021. Hence, with H = 1.0078, 



= 11.9919, ±.0010 



a value which is almost certainly too low. 



For the weight of a normal litre of methane, CH4, Baume and Perrot * 

 find the following values: 



0.71690 



0.71657 



0.71633 



0.71669 



0.71751 



0.71636 



0.71672 



0.71678 



0.71725 



Mean, 0.71689, ± .000098 



^Journ. Chim. Phys., 6, 46. 1908. Baume also gives data lor methyl chloride, but they are not 

 available for a good determination of molecular weight. 

 ^Compt. Rend., 148, 39. 1909. 



