26 Dv. Schonbein on the vanotis Conditions of Oxygen, 



turpentine, &c. being apparently effected by common oxygen, is 

 typical to mc, because we know, and T think with sufficient cer- 

 tainty, that in those cases the ozonization of common oxygen 

 always precedes oxidation. In order to increase as much as pos- 

 sible the body of evidence in favour of that assumption, I have of 

 late worked a good deal on the oil of bitter almonds (benzule 

 -h H), which, as regards its bearings to common oxygen, is cer- 

 tainly one of the most remarkable bodies I know ; for oxygen at 

 the common temperature, submitted to the joint influence of this 

 oil and solar light, effects a number of oxidations, which only 

 6, but not 0, is capable of causing. Under the circumstances 

 mentioned, iodine is eliminated from iodide of potassium, indigo 

 solution discoloured rapidly, solution of guaiacum blued, a great 

 number of metals oxidized, even silver not excepted, &c. 



To convince yourself of this action in a simple way, add to 

 diluted paste of starch containing some iodide of potassium, a 

 drop or two of hydruret of benzule (free from prussic acid), shake 

 in the dark the mixture together with ordinary oxygen, and no 

 action will result ; make the same experiment in the sun, and 

 the liquids will almost instantaneously be turned deep blue, just 

 as if free ozonized oxygen had acted upon the paste. The same 

 colour will make its appearance if you treat in a similar way a 

 recently prepared solution of guaiacum. To show that even 

 silver is oxidized, put some drops of the oil upon a plate of pure 

 silver, and move the essence about in direct sunlight for a minute 

 or two ; on aqueous sulphuretted hydrogen being poured upon 

 the spot of reaction, a rather abundant precipitation of sulphuret 

 of silver is produced, a proof of the presence of oxide of silver. 

 I need not expressly state that the hydruret of benzule is oxidized 

 along with the metals, in consequence of which benzoates are 

 formed — benzoate of lead, cadmium, copper, silver, &c. A very 

 pretty experiment may be made with metallic arsenic. Deposit 

 round a glass tube a ring of that metal (by means of Marsh's 

 method), drop some oil of bitter almonds upon it, and turn the 

 tube, held in a horizontal position, round its axis : no action takes 

 place in the dark, whilst in the direct solar light the ring will 

 rapidly disappear under the circumstances indicated, arsenic acid 

 being formed, just as is the case in ozonized oxygen. Rings 

 of antimony being not acted upon, or at least but very slightly, 

 under these circumstances, the two metals may be easily distin- 

 guished from each other by means of hydruret of benzule. Tiie 

 details of my researches on the od of bitter almonds will before 

 long be published by the Academy of Paris. 



You arc aware that nitrification has been these many years a 

 matter of interest and research to me, and of late I have increased 

 our knowledge of that subject by some novel facts. Some years 



