FERMENTATION AND PUTREFACTION. 297 



tion of a salt of magnesia, also, which is not rendered 

 turbid by the addition of phosphate of ammonia, de- 

 posits the phosphate of magnesia and ammonia on 

 those parts of the vessel touched with the rod em- 

 ployed in stirring. 



In the processes of combination and decompo- 

 sition under consideration, motion, by overcoming 

 the vis inerticB, gives rise immediately to another 

 arrangement of the atoms of a body, that is, to the 

 production of a compound which did not before 

 exist in it. Of course these atoms must previously 

 possess the power of arranging themselves in a cer- 

 tain order, otherwise both friction and motion would 

 be without the smallest influence. 



The simple permanence in position of the atoms 

 of a body, is the reason that so many compounds ap- 

 pear to present themselves, in conditions, and with 

 properties, different from those which they possess, 

 when they obey the natural attractions of their atoms. 

 Thus sugar and glass, when melted and cooled rapid- 

 ly, are transparent, of a conchoidal fracture, and 

 elastic and flexible to a certain degree. But the 

 former becomes dull and opaque on keeping, and 

 exhibits crystalline faces by cleavage, which belong 

 to crystallized sugar. Glass assumes also the same 

 condition, when kept soft by heat for a long period ; 

 it becomes white, opaque, and so hard as to strike 

 fire with steel. Now, in both these bodies, the com- 

 pound molecules evidently have different positions 

 in the two forms. In the first form their attraction 

 did not act in the direction in which their power of 

 cohesion was strongest. It is known, also, that when 

 sulphur is melted and cooled rapidly by throwing it 

 into cold water, it remains transparent, elastic, and 

 so soft that it may be drawn out into long threads ; 

 but that aftei* a few hours or days, it becomes again 

 hard and crystalline. 



The remarkable fact here is, that the amorphous 

 sugar or sulphur returns again into the crystalline 

 condition, without any assistance from an exterior 



