94; Dr. T. Thomson on Pyroxylic Spirit and its Compounds. 



Equivalent to C^ H^ O + C' H* 0\ Thus it agrees in its 

 composition with all the preceding compounds. 



8. Oxy-cJiloro-carhonate of methylene. — When pyroxylic 

 spirit is introduced to a glass vessel filled with chloro-carbonic 

 acid the temperature rises suddenly, and the reaction is ter- 

 minated in a very short time. Muriatic acid is formed, and 

 chloro-carbonate of methylene, which separates under the 

 form of a heavy oil when the pyroxylic spirit employed con- 

 tains some water. It is easily separated from the water by 

 decantation. It must then be rectified by distilling it by the 

 vapour-bath over a great excess of chloride of calcium and 

 massicot. Should it be suspected of still retaining any pyr- 

 oxylic spirit, it may be digested without heat over fragments 

 of chloride of calcium. 



Thus purified it is a colourless liquid, very fluid, has a pe- 

 netrating odour, is very volatile, and heavier than water. It 

 burns with a green flame. 



From the analysis of Dumas and Peligot, it follows that 

 the constituents of this chloro-carbonate are 



Carbon 25 '5 7 or 4 atoms = 3 or per cent. 2.5*26 

 Hydrogen 3-46 or 3 atoms = 0*375 — — 3*16 

 Chlorine 37-12 or 1 atom = 4<*5 — — 37*90 



Oxygen 33*85 or 4 atoms = 4*0 — — 33*68 



100-00 11*875 100*00 



Equivalent to C^ H^ O + (C^ O'^) Chi. 



An atom of the water which enters into the constitution of 

 pyroxylic spirit is decomposed, its hydrogen uniting to the 

 chlorine of the chloro-carbonic acid, and converting it into 

 muriatic acid, while the oxygen takes the place of that chlo- 

 rine ; so that 2 atoms of chloro-carbonic acid, C^ O^ ChP, 

 become C^ O"^ Chi, or an atom of oxychloro-carbonic acid*. 



9. Chlorocyanate of methylene. — This compound was dis- 

 covered in 1837 by M. Aime, who obtained it by passing a 

 current of chlorine through a solution of cyanodide of mer- 

 cury in pyroxylic spirit f, and washing the liquid that di- 

 stilled over in water. 



Its specific gravity is 1*25. It boils at a heat under 122°. 

 It burns with a red flame, green round the edges. Ammonia 

 decomposes it immediately, and water in a few days. It is 

 composed of 



1 atom chloride of cyanogen ... C^ Az Ch 

 1 atom methylene C^ FF O 



10. Cyanate of methylene. — This compound was formed in 



* Ann, (le Chivi. et de Vhys,.^ Ixiii. 52. f Ihid. Ixiv. 222. 



