358 TRANSACTIONS OF THE 



reasons given, causes chemical action, in different degrees, to take 

 place. In some substances opposite effects are produced, al- 

 ways in these, eremacausis or decay. It therefore follows that 

 where fruit is not kept closely packed, it should be exposed to as 

 little change of temperature as possible, and should also be pre- 

 served from the full effects of an atmosphere saturated with 

 moisture. It may be here observed, all good authority agree that 

 wiping the fruit is injurious, as it takes off the hloom^ the use of 

 which is a protection from moisture. Some fruit-growers are so 

 well aware of this that they will not handle their choice fruit in 

 gathering, except by the stalk. Light is found to be injurious. 

 All men of experience say fruit keeps best in the dark. Total 

 darkness is recommended. This arises from a specific stimulus 

 being exercised upon the vegetable tissue by this agent. Light 

 causes evaporation. As soon as it is withdrawn it ceases. 



It is evident decay is greatly promoted by heat and light^ and 

 by the presence of alkalies. It is on the contrai-y arrested or re- 

 tarded by cold, dryness, many salts and absorbents being used. 

 Gay Lussac has shown that the atmosphere coming into contact, 

 for a short time, with fruit will cause fermentation. This 

 would continue in fruit, though not long exposed to the air. 

 Fruits decaying produce ammonia, hydrogenic acid, and water. 

 These when brought into contact with muriatic are decomposed 

 into formic acid and ammonia. Charcoal being the most indiffer- 

 ent, has the power of condensing ammonia and formic acid, (be- 

 fore reaching the freezing point.) 



As soon as the action of the air ceases, that is, as soon as de- 

 prived of oxygen, the humus suffers no farther change. Sub- 

 stances that contain nitrogen are, on examination, most prone to 

 putrefaction. When the decomposition of such substances is 

 effected with the assistance of water, their nitrogen is invariably 

 liberated in the form of ammonia. "TVm is a fixed rule without 

 exceptions^ whatever may he the cause that produces the decompo- 

 sition. Every azotised constituent of the ajiimal or vegetable 

 organism enters spontaneously into putrefaction.^ when exposed to 

 moisture and a higher temperature.'''' Fermentation may be con- 

 sidered as a process of combustion or oxidation of a similar kind 

 taking place in a liquid between the elements of the same matter 

 at a very slightly elevated temperature, and putrefaction, as a 

 process of oxidation, in which the oxygen of «// the substances 

 present comes into play. Eremacausis or decay takes place in 

 organic substances, in contact with air or oxygen. But these 



