The identity of the four valencies of the carbon atom follows from the fact that the heats of combustion of methane, ethane, propane, trimethyl methane, and tetramethyl methane, have a constant difference in the order given, viz.
Ammonium iodide assumes cubic forms with perfect cubic cleavage; tetramethyl ammonium iodide is tetragonal with perfect cleavages parallel to {100} and {o01} - a difference due to the lengthening of the a axes; tetraethyl ammonium iodide also assumes tetragonal forms, but does not exhibit the cleavage of the tetramethyl compound; while tetrapropyl ammonium iodide crystallizes in rhombic form.
Silicon Tetramethyl, Si(CH3)4 (tetramethyl silicane), and silicon tetraethyl, Si(C2H5)4, are both liquids.
By distilling an alloy of antimony and sodium with mythyl iodide, mixed with sand, trimethyl stibine, Sb(CH 3) 3 i is obtained; this combines with excess of methyl iodide to form tetramethyl stibonium iodide, Sb(CH 3) 4 1.
The stibonium iodide on treatment with moist silver oxide gives the corresponding tetramethyl stibonium hydroxide, Sb(CH 3)40H, which forms deliquescent crystals, of alkaline reaction, and absorbs carbon dioxide readily.