Molecular Effects of Solids. 



301 



52 148. 1 : 8. 



52148. 1 : 11. 



52 147. 1 : 6. 



52149. 1 : 10. 



Molecular Effects of Solids. 



52,146. Molecule Model, 

 I, 2, Fig. 3899) . 



as suggested by Korner, Figure, on stand (Fr. phys. Techn. 



The balls are capable of easy motion round their position of equilibrium. A blow increases the 

 movement which is generally existent, and the development of heat by impact or friction can be shown. 

 A plate is placed on four of the uppermost layer of balls. This is loaded (in a positive or negative 

 sense) with weights. The molecules are compressed or expanded until the action of tensile or com- 

 pressive strength proceeding from them attains equilibrium. 



52.147. Molecule Model, as suggested by Hartl, Figure . . . 



This model has two spheres joined by a spiral spring, each ball representing a molecule. The 

 spring endeavours to bring these together. Two flat springs placed round the molecules represent 

 the surrounding ether envelopes, the molecules being held apart by these flat springs. The simul- 

 taneous attraction and repulsion is plainly observable in this model. 



52.148. Tribometer (HartPs) (Ztschr. f. d. phys. u. chem. U., 7, 1893/94, p. 231), Figure, 

 for experiments on sliding friction, the inclined plane, etc 



The tribometer is a demonstration dynamometer, and permits of reading on a scale, even at 

 some distance away, the force used. A sliding track forms the lower surface, and this track can be 

 laid with slabs of different materials. The sliding bodies are wood blocks covered with different materials. 

 Given in with the apparatus are 3 slabs, one of glass ground on one side and polished on the other; 

 one slab of cast iron, planed, and one of brass. An oak block is given in as a sliding body, as are also 

 a block covered with drawing paper and one covered with brass. 



52.149. Tribometer for Sliding Friction, as suggested by Coulomb, Figure (M. P. I, Fig. 341 

 [330]), with one pair horizontal bearing rails of wood and of iron, with roller and balance 

 pan, also a large selection of test materials 



s. d. 

 1.10.0 



0.15.0 



15. 0.0 



2.10.0 



For Brake Dynamometers (Prony Brakes), see Nos. 52,424 52,426, p. 332. 



Cl. 3S91, 681, 



5279, 682. 



