Dr. T. Tliomson on Pijroxylic Spirit and its Compounds. 89 



decided odour of hydrocyanic acid. The temperature gra- 

 dually rises to 151°. What comes over at that temperature 

 is considered by Dumas and Peligot to be in as pure a state 

 as they could procure it . 



It is a colourless liquid, having a specific gravity of 1*182 

 at the temperature of 71°. It boils at 151°, giving out a 

 weak ethereal odour. It is perfectly neutral, and burns with 

 a lively yellow flame. When the vapour is heated to about 

 302°, it detonates with great violence, so as to produce dan- 

 gerous results if the quantity be considerable. 



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

 per. The result of 5 analyses made in this way led to tlie 

 conclusion that it was composed of 



2 atoms carbon = 1'5 



3 atoms hydrogen =0*375 



1 atom azote = 1*75 



6 atoms oxygen = 6*00 



9*625 

 This is equivalent to C^ H^ O + N O^ 



They found the specific gravity of the vapour of nitrate of 

 methylene to be 2*640. Now, 



1 volume methylene = 1*5972 



1 volume nitric acid vapour = 3*7500 



2)5*34.72 



2*6736 

 This result agrees as nearly as could be expected with the 

 specific gravity of the vapour found. 



When pyroxylic spirit is treated with nitric acid and silver, 

 in the well-known method for obtaining detonating silver, no 

 violent action takes place. Nitrate of methylene distils over ; 

 and towards the end of the process, if the nitric acid was 

 strong, oxalate of silver is deposited*. The same thing hap- 

 pens when we substitute mercury for silver. 



3. Oxalate of methylene. — The method of obtaining this 

 compound, is to distil a mixture of equal parts sulphuric acid, 

 oxalic acid, and pyroxylic spirit. There passes over into the 

 receiver a spirituous liquor, which, when exposed to the air, 

 speedily evaporates, leaving a residue crystallized in fine 

 rhomboid plates. As the distillation proceeds, the quantity 

 of this crystalline matter increases. At last the whole liquors 

 that pass over assume a solid consistency. When the distil- 

 lation is terminated, if we allow the retort to cool, and add 



* Dumas and Peligot, Ann. dc Ckini, ci de Phi/s.s.]. 195. 



