152 Olservatlons on the Prussic Acid, &c. 



IV. The liquor which passed throucvh had in the course 

 of a t'cw hours, and this perhaps would have been the case 

 sooner had I leit it at rest, deposited at the bottom an oil 

 which appeared yellowish, and which could not be mixed 

 by shaking it with the supernatant liquor. I suftered it to 

 stand till the next day, in order that I might make more 

 accurate observations in the day-time ; but saw with asto- 

 nishment that the oil had disappeared, and had left in its 

 place a cr^'stalline precipitate, which, though small^ exhi- 

 bited all the pha^nomena of prussiate of potash. I here 

 suspended all further research, as I was not able to repeat 

 the experiment with sufficient accuracy, and therefore re- 

 served it for further examination. It was, however^ esta- 

 blished by the first and second experiments, that by this 

 process prussiate of potash, free from iron, can be pro- 

 duced. But if carbonic acid v.-as combined with the prussic 

 acid, an idea I was led to take up by the difference of the 

 crystals which were produced, and by the greenish blue 

 precipitate, it is natural to suppose that the latter expelled 

 the former in part, and mixed also with a part of the 

 potash ; and, therefore, the prussiate of potash must have 

 been separated from the prussic' acid. 



Berthollet's experiment, in which he treated prussic acid 

 with oxygenated muriatic acid, was here of importance*. 

 The prussic acid was decomposed, and an oil was pro- 

 duced : the oil in water sank to the bottom : it no longer 

 reacted like the prussic acid on combinations of iron : it 

 was not inflammable: it evaporated in heat, and in course 

 of time was converted into small crystals. If I entertained 

 any doubts in regard to my own experiments, this coinci- 

 dence in some manner removed them. The same phseno- 

 menon was confirmed by an experiment of a quite dift'erent 

 kind, where an oil was produced by the action of alcohol 

 on the prussic acid and carbonate of potash. The confir- 

 mation of Berthollet's experiment affords cause for more 

 accurate research in regard to the fundamental mixture of 

 prussic acid, oil, and alcohol. 



It still remains to be examined, whether the oil produced 

 in this nianner, according to my experiment, was prussic 

 acid. It was possible that the crystals produced might have 

 been again taken up by the fluid, and even by the air, 

 which in my experiments was quite filled with it. Whether 

 the oily fluid produced was really an oil, I was not funher 

 able to dctcrmmc; but by shaking it with the watery fluid 



* Crcli'a Ar.nakn, 1790, vol. i. p. 186. 



I divided 



