102 



AGRICULTURAL CHEMISTRY. 



been induced by mere contact with matter 

 in the state of eremacausis. The action of 

 the decaying substance here produced results 

 exactly similar to those effected by spongy 

 platinum; but that they proceeded from a 

 different cause was shown by the fact, that 

 the presence of carbonic oxide, which ar- 

 rests completely the action of platinum 

 on carburetted hydrogen, did not retard in 

 the slightest degree the combustion of 

 the hydrogen in contact with the decaying 

 bodies. 



But the same bodies were found by De 

 Saussure not to possess the property just 

 described, before they were in a state of fer- 

 mentation or decay ; and he has shown that 

 even when they are in this state, the pre- 

 sence of antiseptic matter destroys com- 

 pletely all their influence. 



Let us suppose a volatile substance con- 

 taining a large quantity of hydrogen to be 

 substituted for the hydrogen gas in DeSaus- 

 sure's experiments. Now, the hydrogen in 

 such compounds being contained in a state 

 of greater condensation would suffer a more 

 rapid oxidation, that is, its combustion 

 would be sooner completed. This principle 

 is in reality attended 10 in the manufactories 

 in which acetic acid is prepared according 

 to the new plan. In the process there 

 adopted all the conditions are afforded for the 

 eremacausis of alcohol, and for its conse- 

 quent conversion into acetic acid. 



The alcohol is exposed to a moderate 

 heat, and spread over a very extended sur- 

 face, but these conditions are not sufficient 

 to effect its oxidation. The alcohol must be 

 mixed with a substance which is with faci- 

 lity changed by the oxygen of the air, and 

 either enters into eremacausis by mere con- 

 tact with oxygen, or by its fermentation or 

 putrefaction yields products possessed of this 

 property. A small quantity of beer, aces- 

 cent wine, a decoction of malt, honey, and 

 numerous other substances of this kind, 

 possess the action desired. 



The difference in the nature of the sub- 

 stances which possess this property shows, 

 that none of them can contain a peculiar 

 matter which has the property of exciting 

 ^remacausis ; they are only the bearers of an 

 action, the influence of which extends be- 

 yond the sphere of its own attractions. 

 Their power consists in a condition of de- 

 composition or eremacausis, which im- 

 presses the same condition upon the atoms 

 of alcohol in its vicinity ; exactly as in the 

 case of an alloy of platinum and silver dis- 

 solving in nitric acid, in which the platinum 

 becomes oxidised, by virtue of an inductive 

 action exercised upon it by the silver in the 

 act of its oxidation. The hydrogen of the 

 alcohol is oxidised at the expense of the 

 oxygen in contact with it, and forms water, 

 evolving heat at the same time; the residue 

 is aldehyde, a substance which has as great 

 an affinity for oxygen as sulphuric acid, and 

 combines, therefore, directly with it, pioduc- 

 ing acetic acid. 



CHAPTER VIII. 



EREMACAUSIS OF SUBSTANCES CONTAINING 

 NITROGEN. NITRIFICATION. 



WHEN azotised substances are burned at 

 high temperatures, their nitrogen does not 

 enter into direct combination with oxygen. 

 The knowledge of this fact is of assistance 

 in considering the process of the eremacau- 

 sis of such substances. Azotised organic 

 matter always contains carbon and hydro- 

 gen, both of which elements have a very 

 strong affinity for oxygen. 



Now nitrogen possesses a very feeble 

 affinity for that element, so that its com- 

 pounds during their combustion present 

 analogous phenomena to those which are 

 observed in the combustion of substances 

 containing a large proportion of hydrogen 

 and carbon ; a separation of the carbon of 

 the latter substances in an uncombined state 

 takes place, and in the same way the sub- 

 stances containing nitrogen give out that 

 element in its gaseous form. 



When a moist azotised animal matter is 

 exposed to the action of the air, ammonia is 

 always liberated ; nitric acid is never formed. 



But when alkalies or alkaline bases are 

 present, a union of oxygen with the nitrogen 

 takes place under the same circumstances, 

 and nitrates are formed together with the 

 other products of oxidation. 



Although we see the most simple means 

 and direct methods employed in the great 

 processes of decomposition which proceed 

 in nature, still we find that the final result 

 depends on a succession of actions, which 

 are essentially influenced by the chemical na- 

 ture of the bodies submitted to decomposition. 



When it is observed that the character of 

 a substance remains unaltered in a whole 

 series of phenomena, there is no reason to 

 ascribe a new character to it, for the pur- 

 pose of explaining a single phenomenon, 

 especially where the explanation of that ac- 

 cording to known facts offers no difficulty. 



The most distinguished philosophers sup- 

 pose that the nitrogen in an animal sub- 

 stance, when exposed to the action of air, 

 water, and alkaline bases, obtains the power 

 to unite directly with oxygen, and form ni- 

 tric acid, but we are not acquainted with a 

 single fact which justifies this opinion. It 

 is only by the interposition of a large quan- 

 tity of hydrogen in the state of combustion 

 or oxidation, that nitrogen can be converted 

 into an oxide. 



When a compound of nitrogen and cai 

 bon, such as cyanogen, is burned in oxygeu 

 gas, its carbon alone is oxidised ; and when 

 it is conducted over a metallic oxide heated 

 to redness, an oxide, of nitrogen is very 

 rarely produced, and never when the carbon 

 is in excess. Kuhlmann found in his ex 

 periments, that it was only when cyanogen 

 [ was mixed with an excess of oxygen gas 

 and conducted over spongy platinum, that 

 nitric acid was generated. 



