Dr. J. Stenhouse on Chloropicrine. 53 



the circuit was interrupted in consequence of the fracture of 

 one of the porous cells, which caused the dilute and concen- 

 trated acids to mingle together, and, consequently, to boil 

 over, until the porous and cast-iron cells were nearly emptied. 

 Notwithstanding this interruption of the circuit, the arc of 

 light between the coke points was about an inch long, and the 

 heat of the flame deflagrated a file. 



I had arrangements made for a long series of experiments 

 on the decomposing power of the voltaic current, and of vol- 

 taic heat, and on the illuminating power of the various kinds 

 of voltaic light; but these experiments I was obliged to omit, 

 through fatigue, exhaustion, and bad health. I have since 

 tried the illuminating power of the light produced by the 

 ignition of coke points; and for the gas microscope and pola- 

 riscope have found it far superior to the oxyhydrogen lime 

 light. With good coke points, abundant light for the micro- 

 scope and polariscope may be obtained from a battery con- 

 taining 25 cast-iron cells, and as many zinc plates, each 2 

 inches by 4: if the coke be not very good, 40 plates will be 

 required. When an iron cell, 2| inches wide and 4 inches 

 high, is large enough to contain between it and the porous 

 cell nearly a wine-glassful of the concentrated acids, the bat- 

 tery will work with undiminished power for about three hours 

 without any additional acid. If the cell containing the zinc 

 plates be small, it will be necessary to pour in a little dilute 

 acid every half-hour. I have got the lime light by igniting 

 the mixed gases as they were produced by the decomposition 

 of water, and throwing the flame on lime. 



Maynooth College, April 6, 1848. 



X. On Ohloropicrine. By John Stenhouse, Esq., Ph.D.* 



WHEN an aqueous solution of nitropicric acid is poured 

 into a retort containing a great excess of hypochlorite 

 of lime, the mixture heats spontaneously, and an aromatic 

 pungent vapour, which affects the eyes very powerfully, is 

 immediately evolved. If heat is applied to the retort so soon 

 as the mixture begins to boil, a very large quantity of a co- 

 lourless heavy oil comes over along with the vapours of water, 

 and condenses in the receiver. To this oil I purpose giving 

 the name of chloropicrine. When the mixture has boiled for 

 a quarter of an hour or so, the whole of the oil has usually 

 passed over; and if the liquid in the retort is perfectly colour- 



• Communicated by the Author. 



