Dr. T. Thomson on Pyi'oxylic Spirit and its Compounds. 93 



Now these atomic numbers may be grouped as follows: — 

 1 atom methylene = C^ H-^ O 



1 atom benzoic acid = C'^H^ O' 



Thus its constitution is precisely similar to that of the other 

 salts of methylene which have been already described. 



Dumas and Peligot found that benzoate of methylene may 

 be obtained by distilling a mixture of dry benzoate of soda 

 and neutral sulphate of methylene. 



The specific gravity of the vapour of benzoate of methy- 

 lene, as determined by Dumas and Peligot, is 4'717. Now 



1 volume methylene gas = 1*5772 



1 volume benzoic acid vapour = 7*8475 



2)9*4247 



4*7123 

 7. Mncate of methylene, — This compound was first formed 

 in 1836, by M. Malagutti*. The process for preparing it is 

 precisely the same as that for preparing mucic aether, only 

 substituting pyroxylic spirit for alcohol. 



It is solid, crystallized, colourless, fixed, and insipid. It 

 may be obtained in crystals, either from alcohol or water, but 

 the crystals are not so distinctly shaped as those of mucic 

 aether. When viewed with a microscope they appear to be 

 rectangular prisms with beveled summits. 



When heated, the mucate of methylene undergoes decom- 

 position before it melts. Decomposition begins at the tem- 

 perature of 325^°, and shows itself by the evolution of a 

 black oily matter; at 345°*2 it assumes the form of a black 

 liquid, which swells and gives out carburetted hydrogen. 



It is very little soluble in boiling alcohol, one part requiring 

 200 of alcohol of 0*814 to dissolve it. When the solution 

 cools the mucate almost all falls under the form of a crystalline 

 powder. It is very soluble in boiling water ; but partly pre- 

 cipitates as the solution cools. The specific gravity of the 

 crystals from alcohol is 1*48, that of those from water 1*53. 



M. Malagutti analyzed this mucate of methylene, and ob- 

 tained 



Carbon 40*16 or 8 atoms = 6 or percent. 40*34 



Hydrogen 5*91 or 7 atoms = 0*875 — — 5*88 



Oxygen 53*93 or 8 atoms — 8*0 — — 53*78 



100*00t 14*875 100*00 



• Ann. de Chim. et de Phys., Ixiii. 94. f Ibid, p. 295. 



