88 Dr. T. Thomson on PijroxyUc Sinrit and its Compounds. 



The sulphate of methylene may not only be distilled over 

 without alteration, but it may be heated to 392° without un- 

 dergoiuf^ any decomposition. It is slowly decomposed by 

 cold water, and rapidly by boiling water. The last acts with 

 violence, evolving much heat, and the sulphate disappears 

 altogether, without producing any new oil. Sulphomethylic 

 acid is formed, and pyroxylic spirit is regenerated. 



Caustic barytes has no action on it. Hydrate of barytes, 

 and the hydrated alkalies, or their aqueous solutions, decom- 

 pose it with great facility. Thus, solution of potash converts 

 it, with much heat, into sulphomethylate of potash and pyr- 

 oxylic spirit. 



By means of sulphate of methylene all the other com- 

 pounds of methylene and acids may be obtained. Thus, when 

 heated with fused common salt, sulphate of potash is formed, 

 and muriate of methylene is disengaged in the gaseous form. 

 When heated with fluoride of potassium, hydrofluate of me- 

 thylene is disengaged in the gaseous state. When heated with 

 cyanodide of mercury, or of potassium, sulphate of potash, 

 or sulphate of mercury is formed, and cyanodide of methy- 

 lene may be collected in the liquid form. When it is di- 

 stilled with benzoate of potash, we obtain benzoate of methy- 

 lene ; and so on. 



When 2 parts of pyroxylic spirit, 2 parts of binoxide of 

 manganese, and 3 parts of sulphuric acid, diluted with their 

 own weight of water, are mixed, a violent effervescence takes 

 place, and a great deal of formic acid is evolved. The other 

 products from the distillation of this mixture have been ex- 

 amined with great care by Mr. Kane*. 



2. Nitrate of methylene. — This compound was obtained by 

 Dumas and Peligot by putting into a retort .^0 parts of nitre, 

 ]00 parts of sulphuric acid, and 50 parts of pyroxylic spirit. 

 The retort should be large, and connected with a large receiver 

 communicating with a bottle containing salt water, and sur- 

 rounded with a refrigerating mixture, and from this should 

 pass a tube capable of conducting the gas formed into the 

 chimney. It is only necessary to apply heat at the com- 

 mencement of the process. Ai'terwards it goes on of its own 

 accord. When the process is finished, the liquid in the re- 

 ceiver is poured into the bottle. In this way we obtain at 

 tlie bottom of the bottle a colourless layer of the new com- 

 pound. It must be separated by decantation and purified by 

 distilling it off" a mixture of massicot and chloride of calcium. 



Thus prei)ared it is impure. If it be heated to the tem- 

 perature of 140°, il boils and gives off a substance having a 



• Jnnalen dcr Pliarmacic, xix. 175. 



