216 ORIGIN OF THE NITRATES. 



change of alcohol into potassium acetate, when in contact with 

 dilute potash, liberates 13 Calories more than its change into 

 free acetic acid. 



The oxidation itself often becomes more thorough under the 

 influence of this additional work, which further increases the 

 liberation of heat. This is the case with alcohol. It is well 

 known how difficult it is to oxidise alcohol by free oxygen at 

 a low temperature and without a medium. It is necessary to 

 raise the alcohol, taken by itself, to a very high temperature in 

 order to cause it to absorb oxygen, forming at first aldehyde 

 and acetic acid. But it is otherwise if alcohol be placed in 

 presence of oxygen and of an alkali simultaneously ; then the 

 alcohol is gradually oxidised at the ordinary temperature, and 

 it forms not only acetic acid, but even oxalic acid, or rather an 

 oxalate. Now the transformation of alcohol into dissolved 

 potassium oxalate liberates a quantity of heat (288) nearly 

 double that produced by the transformation of alcohol into 

 acetate (136). 



Phenomena of the same kind are very common in organic 

 chemistry. They certainly play a part in natural nitrification. 

 In the author's opinion their interpretation should be sought in 

 thermo-chemical considerations, seeing that chemical reactions 

 are the easier, cceteris paribus, the greater the amount of heat 

 liberated by them. 



11. We shall show, lastly, how an analogous concurrence may 

 be brought about, under the hypothesis that the nitrates result 

 directly from the oxidation of nitrogenous organic principles. 

 It will be sufficient, to take an exact instance, to calculate 

 approximately the heat liberated in the nitrification of hydro- 

 cyanic acid, or rather of potassium cyanide, a calculation not 

 without interest in itself, the cyanides often existing in bricks 

 and other materials capable of nitrification. Take, therefore, 



CNK dissolved + 50 = KN0 3 -h C0 2 gas. 



The heat liberated amounts to + 177 Cal. It is nearly 

 double the heat liberated in the nitrification of ammonia, at 

 the expense of dissolved potassium carbonate. This excess is 

 due in a great measure to the oxidation of the carbon ; it is 

 probably to be met with in the oxidation of the other nitro- 

 genous organic substances. Gaseous hydrocyanic acid and 

 dilute potash would liberate + 186 Cal. in yielding an equivalent 

 of potassium nitrate. 



Lastly, dissolved ammonium cyanide and potash absorb nine 

 equivalents of oxygen in being transformed into potassium 

 nitrate 



CNH.NHs dilute + K 2 dilute + 90 = 2KN0 3 dilute + C0 2 



gas + 2H 2 0, 



