DEMONSTRATION MATERIAL IN GEOLOGY 59 



B. Experiments on the physical-chemical behavior of chemical systems at dif- 



ferent temperatures and pressures : 



1. Crystallization phenomena. 



(a) Types of crystallization; effect of load. 



(b) Supersaturation. 



(c) Eutectics. 



(d) Sequence of crystallization. 



(e) Equilibria conditions. 

 (/) Melting phenomena. 

 (g) Inversion phenomena. 



(h) Gravitative settling and floating of different compounds on 

 crystallization. 



(i) Exothermic and endothermic reactions. 



(j) Two component systems. 

 (k) Zonal structure. 



2. Liesegang experiments with colloids. 



3. Settling of clays and suspensoid colloids. 



4. Chemical corrosion. 



5. Melting phenomena on ice blocks to illustrate iceberg formation. 



Melting of ice under load. 



C. Physical phenomena. 



(a) Geyser action. 



(J)) Underground flow of water. Pore space. 

 (c) Deposition of sediments in running water. (Experiments 

 of Gilbert). 



D. The principle of equilibrium. 



Most of the experiments listed above require simple, inexpensive apparatus 

 only and might well be incorporated in a general course on geology. It should 

 not be difficult to interest some manufacturer in the production of the required 

 apparatus. A pamphlet describing these experiments might well be prepared 

 by several geologists acquainted with the different phases of the work. 



Most of the apparatus suggested by Wright is more suitable for ad- 

 vanced than for elementary students. 



In addition to the apparatus suggested by Fred E. Wright, the follow- 

 ing is desired by one or more geologists : 



1. Apparatus to show the formation of volcanic cones of the explosive 

 type. 



2. Apparatus to show the method and origin of the Great Basin faults. 



3. iVpparatus for demonstrating folding. 



4. Apparatus to show the operation of seismographs. 



5. J. B. Woodworth suggests a piece of apparatus which he describes 

 as follows: 



"Draw an outline of the continent, with its political divisions and such other 

 features as may be desired, on some form of flexible weighted stuff, so that 

 the surface so prepared will rise and fall here and there above and below a 



