1914-15.] Interaction of Methylene Iodide and Silver Nitrate. 227 
XXII. — The Interaction of Methylene Iodide and Silver Nitrate. 
By Professor 0. R. Marshall and Elizabeth Gilchrist, M.A., B.Sc. 
(MS. received July 5, 1915. Eead July 5, 1915.) 
In the course of some experiments, designed to prepare methylene nitrate, 
an interesting reaction between methylene iodide and silver nitrate in 
alcoholic solution was observed. When approximately an equimolecular 
quantity of methylene iodide is added to a saturated solution of silver 
nitrate in methyl or ethyl alcohol, glistening white crystals quickly^ begin 
to appear and soon form a bulky precipitate. 
Scholl and Steinkopf {Ber., xxxix, p. 4397, 1906) obtained a similar 
crystalline precipitate on dropping 6*7 gms. methylene iodide into a 
solution of 8‘5 gms. silver nitrate in 17 gms. water, constantly stirred and 
kept cool with ice. The crystals were washed with anhydrous acetone 
and afterwards with anhydrous ether. The yield was 10 gms. The 
determination of the carbon, hydrogen, and silver suggested the formula 
AgN 03 .CH 2 l 2 . The compound had a slight methylene iodide odour, 
decomposed slowly and became yellowish at ordinary temperatures, melted 
with decomposition at 80°-81° C., and was immediately decomposed by 
water and more slowly by alcohol with formation of silver iodide. It was 
not further examined. Donnan and Potts {Journ. Chem. Soc., XCVII, ii, 
p. 1895, 1910) made a few experiments to determine the velocity co- 
efficient of the reaction between methylene iodide and silver nitrate in 
alcoholic solution, which will be referred to later. 
The substance obtained by us appears to be the same compound as that 
described by Scholl and Steinkopf. The crystals are colourless when pure 
and become yellowish and finally greyish or greenish grey on the surface 
when exposed to light. They have a faint odour of methylene iodide. 
If left exposed to air in the dark the compound is largely converted into a 
mixture of silver iodide and silver nitrate, the proportions varying with 
the conditions of exposure. If exposed in thin layers more nitrate is 
formed ; if exposed in bulk the iodide preponderates. When heated, the 
crystals decompose at 79°-80° C. with evolution of iodine and nitrous 
fumes. Heated in a dry test-tube, nitrous fumes seem to come off first, 
but if warmed under a layer of xylol or liquid paraffin the liquid 
becomes violet and nitrous fumes do not appear until the temperature 
is further raised. 
