THE BEGINNINGS OF LIFE 



43 



ni. 



^H DETERja>,-j pounds 



dissociating agency of heat, which tends to increase 

 the distance between the ultimate atoms and molecules 

 of bodies 1. The chemical affinities holding together 

 the constituent atoms or molecules of certain com- 



feeble to withstand the 



^E. 



are. however, too 



dissociating influence of an intense amount of heat. 



As the temperature rises, the chemical affinities which 

 Plained. Actions bind together the dissimilar atoms into compound 

 1- Modes of prec- molecules become more and more weakened, and may 



Bodies depended 



Simple and co: 



to Colloids. Co: 



be at last overcome before liquefaction takes place. 

 Still larger is the number of compounds which are 



F 



of Union. M-; unable to endure the disruptive agency of the higher 



temperatures necessary to reduce them to the state of 



In the case of those substances, more- 



der different 'fe 

 Dr. BennetfbC; 



. of these. Ste g^S ^^ ^aP°^^ 



11 tji LUt3^-. Ullu. 



Albumenoid te ^ver, which are capable of being reduced to either 

 ' living ' Matter, physical condition by the aid of heat, innumerable 



as Heat acts ra;: 

 d Organisms. ^'^^ 

 pencer, andG.E- 

 er, in GroM'tliof^ 



\ ■ 



^ ' Bunsen and Hopkins have shown that substances which expand 

 when fused have their point of fusion raised by mechanical pressure, 

 that is to say, since mechanical force must be overcome in melt- 

 nuui'-^ — V ing, the tendency to melt must be overcome by heat before that 

 alline Matter. ,^ opposition can be overcome ; and the pressure required to keep them 

 1115 producible ^qX^^ at any temperature above their natural point of fusion may be 

 > Iodide '^^^ ^ . looked upon as the mechanical representative of the force with which 



rmmes 



V 



ed 



Ltion 



are 



c 



they tend to fuse at that temperature. Prof W. Thomson has shown 

 that, on the contrary, water, which expands in freezing, has its point 

 of fusion lowered by pressure ; that is to say, since mechanical force 

 must be overcome by crystallizing, crystallization w 1 not take place 

 under increased pressure, unless the force of crystalline polarity be 



mEy ^ increased by reducing the temperature. . . . Similar principles hold true 



in 



accor 



many ^ 



most P^^' 



u^ij, with respect to the solubility of salts in water.' — Bakerian Lecture, ' On 

 the Direct Correlation of Mechanical and Chemical Forces,' by H. 



ei 



C. Sorby (* Proceed, of Royal Soc' vol. xii. 1863, p. 540). 



e 



