716 PRELIMINARY OBSERVATIONS. 



eremacausis seems to be entirely prevented when water is 

 excluded, or when the substance is exposed to a temperature 

 of 32. The processes of fermentation and putrefaction, which 

 are different from eremacausis, appear to be necessarily preceded 

 by an absorption of oxygen. Thus the juice of grapes pressed 

 under mercury and collected in a jar filled with that metal was 

 observed by Gay-Lussac to keep without change, but on ad- 

 mitting a bubble of air to the liquid, the vinous fermentation 

 immediately commenced. The perfect exclusion of air is also 

 the basis of the valuable process for preserving animal and 

 vegetable food, without the use of antiseptics, first introduced 

 by Appert. The materials are usually placed in canisters with 

 a quantity of fluid, which is kept in a state of ebullition for 

 some time, and the openings hermetically closed with solder 

 while the vessels are entirely filled with steam. Eremacausis is 

 also prevented or much retarded by aromatic substances, empy- 

 reumatic substances and oil of turpentine, the vapours of which 

 retard the oxidation of phosphorus and of phosphuretted hy- 

 drogen in a similar manner. It is also arrested by mineral acids 

 and salts of mercury, which appear to act by combining with 

 the organic matter ; alcohol, a strong solution of sugar, common 

 salt and many other saline substances are supposed to owe their 

 antiseptic properties in a great measure to their affinity for 

 water, which reduces animal or vegetable matters in contact with 

 them to a state of dryness in which they are little liable to de- 

 composition. Thus a piece of dry butcher-meat covered with 

 dry salt is found after twenty four hours swimming in brine, 

 the salt attracting water from the meat, and leaving it not humid 

 enough for chemical action. 



ACTION OF CHLORINE, ITS SUBSTITUTION FOR HYDROGEN, 

 CHEMICAL TYPES. 



M. Gay-Lussac observed, several years ago, that bees' wax 

 exposed to chlorine gas absorbed the latter, giving rise to a 

 disengagement of hydrochloric acid, without any change of 

 volume in the gas from the operation. The reason is that the 

 wax loses a volume of hydrogen equal to the volume of chlorine 

 which it absorbs, the constituents of hydrochloric acid gas being 

 united, it is to be remembered, without any condensation of 



