90 Dr. T. Thomson on Pyroxylic Spirit and its Compounds. 



as much pyroxylic spirit as at first, and distil a second time 

 we obtain the same product. 



The crystals from these two distillations being well drained 

 on a filter, are to be melted over an oil-bath to dry them, 

 and distilled over massicot to free them from oxalic acid. The 

 product thus obtained is pure oxalate of methylene. 



It is colourless, and has a smell similar to oxalic aether. 

 It melts at 124<'', and boils at 322°, under a pressure of 30 

 inches of mercury. It dissolves in cold water, and speedily 

 undergoes decomposition when thus dissolved, especially if it 

 be heated, being converted into oxalic acid and pyroxylic 

 spirit. 



It is soluble in alcohol and pyroxylic spirit, and more so- 

 luble when these liquids are hot than when cold. The alka- 

 line hydrates destroy it rapidly, forming oxalates and pyr- 

 oxylic spirit. But anhydrous bases, or at least oxide of lead, 

 do not alter it; anhydrous ammonia converts it into anew 

 substance. Liquid ammonia converts it into oxamide. 



Dumas and Peligot analyzed it by means of oxide of cop- 

 per, and obtained for its constituents 



Carbon 41*08 



Hydrogen 5*28 



Oxygen 53'64. 



100-00 

 These numbers approach 



4 atoms carbon =3 or per cent. 40*68 



3 atoms hydrogen = 0*375 — — 5*08 



4 atoms oxygen =4 — — 54*24 



7-375 100*00 



This is equivalent to C^ H=^ O + C^ O^. 



4. Acetate of methylene. — This compound may be obtained 

 in abundance by distilling a mixture of 2 parts pyroxylic 

 spirit, 1 part crystallizable acetic acid, and 1 part sulphuric 

 acid of commerce. The product obtained is put in contact 

 with a solution of chloride of calcium, which separates an 

 abundant ethereal liquid, containing much acetate of methy- 

 lene. As it still contains some sulphurous acid, and some 

 pyroxylic spirit, it is agitated with quick-lime, and then left 

 to digest over chloride of calcium for 24 hours, which ab- 

 sorbs the pyroxylic spirit. It is a colourless aethereal liquid, 

 having an agreeable odour, analogous to that of acetic tether. 

 It boils at 1362° under a pressure of 30 inches of mercury. 

 Its specific gravity is 0*91 9 at the temperature of 7l|°. Its 

 constituents, determined by the analysis of Dumas and Peli- 

 got, are 



