178 abstracts: physical chemistry 



based upon wrong principles, but a practice which in- some instances 

 produces a reaction far too low for even favorable pancreatic digestion. 

 The addition of alkalies to modified milk for the purpose of preventing 

 firm clots of casein in the stomach is shown to be a procedure which 

 may not only be unnecessary to accomplish this purpose, but one which 

 may involve inhibition of gastric proteolysis and lipolysis. Finally, 

 the addition of alkalies to modified milk is criticized because of its 

 tendency to displace from the intestine a normal fermentative bac- 

 terial flora and to favor bacterial proteolysis or ''putrefaction." 



W. M. C. 



PHYSICAL CHEMISTRY.— r/^e ternanj system: diopside-forsterite- 

 silica. N. L. Bowen. Am. Jour. Sci. (4), 38: 207-264. 1914. 



The results obtained in the investigation of the three binary systems 

 involved are first presented. The system diopside-silica shows the simple 

 eutectic relation, as does also the system diopside-forsterite. The sys- 

 tem forsterite-silica shows one intermediate compound, MgSiOs (clino- 

 enstatite), unstable at its melting-point. 



In the ternary system it is found that clino-enstatite and diopside 

 form a complete series of solid solutions (monoclinic pyroxenes) and 

 therefore have a common field. As a further consequence of this un- 

 broken series of solid solutions there is no ternary eutectic, the lowest 

 point of formation of liquid in the system being the binary eutectic 

 diopside-silica. 



A brief theoretical discussion of solid solution in ternary systems is 

 given. The course of crystallization in typical mixtures of the present 

 ternary system is described, and the value of certain lines termed three- 

 phase-boundaries is pointed out, especially their usefulness in determin- 

 ing the composition of mix-crystals separating at any temperature. In 

 considering crystallization it is shown that crystalhzation may proceed 

 according to two different methods: first, that in which the liquid is, 

 at any temperature, in equilibrium with all the crystals and all parts of 

 the crystals occurring in it, and second, that in which the liquid is in 

 equilibrium at any temperature only with the crystals separating at 

 that temperature. In a general way, crystallization of the second type 

 is favored by quick cooling. 



The importance of distinguishing between the two types of crystalli- 

 zation is great in the present system. It is shown that the difference 

 between the conclusions arrived at in the present work and those ar- 

 rived at in an earlier investigation of the pyroxene series carried out at 

 this Laboratory is due largely to the fact that in the earlier work crys- 



