34 Mr. William Sutherland on the 



same time they show that as the value for CH 2 between the 

 methides and ethides is not far from the truth, the values for 

 the methides may be taken as nearly correct, and where a 

 value for the methide is wanting an approximate one can be 

 got by subtracting from the value for the ethide '75 for each 

 CH 2 . Thus we get the following Table for the methides 

 only : — 



Table XXVI. 



ZnMe a . HgMe 2 . SiMe 4 . SnMe 4 . PbMe 4 . BMe 3 . NMe 3 . PMe 3 . 

 (Wlf, 5-1 57 67 7-5 8-2 5-6 5*5 6-1 



AsMe 3 . SbMe 3 OMe 2 . SMe 2 . OlMe. BrMe. IMe. 

 (M 2 /)* 6-3 0-8 46 5-2 4-0 43 50 



Here again values are given for the methides of N, 0, S, 

 CI, Br, and I, only as checks. The first point to ascertain is 

 whether in the true metallic methides (M 2 /)* follows the laws 

 proper to organic compounds or inorganic metallic compounds. 

 In the organic compounds CH 2 has a value "9, and the other 

 H of CH 3 a value 1*1, so that CH 3 is 2, and thus the values 

 for SiMe 4 and SnMe 4 are less than for Me 4 : therefore the 

 organometallic compounds do not behave as ordinary organic 

 compounds ; but as we have seen the valency of the metallic 

 atoms play an important part in the values of (M 2 Z)* for their 

 inorganic compounds, it will be best to try the effect of 

 treating the methides as we did the metallic chlorides and 

 similar compounds. That is, we must divide the values of 

 (M 2 rp in Table XXVI. by n a , where n is the valency of the 

 metallic atom; then, subtracting 2 for CH 3 from each of the 

 results, we get the values of F/w for the metallic atoms. These 

 are given in the first row of the following table, the second 

 row containing the values from Table XVIII. 



Table XXVII. 



Zn. Hg. Si. Sn. Pb. B. N. P. As. Sb. 

 F/n 1-6 21 1-35 1-75 21 1-2 P2 P5 155 1-9 



F/n from Ta. XVIII. '6 -95 ... -6 ... '8 -85 105 



It appears that the values of F for the metallic atoms in 

 the organometallic compounds are double the values in the 

 inorganic compounds, whether the atoms are dyad, triad, or 

 tetrad ; and this seems to correspond closely with what we 

 found in the stud,' of the ratio B/F for the compound acid 



