1350 Journal of Applied Microscopy 



the important results of the work of these investigators, are clearly of the 

 utmost importance in the future study of this serious disease. h. w. c. 



„,.,., ^^ , . The author studies the bacteria present 



Hilsuiii. Baktenologische Untersuchung eines '^ 



Schwimmbades in Bezug auf Selbstreinig- in a swimming bath which was in con- 

 ung. Cent. f. Bak. u. Par I, 2: 66i, 1901. ^^^^^ ^ge. He finds that the number 



of bacteria increased regularly during the first day, after being newly filled with 

 water, and then constantly decreased. This decrease in the number of bacteria, 

 he points out, could be due neither to the action of light nor to sedimentation, 

 since the number of bacteria at night and morning was essentially the same, and 

 since the water was in constant use, a condition which would prevent sedimen- 

 dation. Nor does he believe that a want of food can be the cause, since the 

 water filtered through a pasteur filter is an excellent culture medium for bacteria. 

 The author believes that the matter is one of struggle among different bacteria 

 with each other, resulting in a destruction of many individuals. h. w. c. 



NOTES ON RECENT MINERALOGICAL 

 LITERATURE. 



Alfred J. Moses and Lea McI. Luquer. 



Books and reprints for review should be sent to Alfred J. Moses, Columbia University, 



New York. N. Y. 



Viola, C. Ueber das "Glaukisiren" verschied- The writer proposes the term " Glau- 

 ener Feldspathe. Zeit. f. Kryst. 34: 171- kisiren " for the variety of schilleriza- 

 195, 1901. . . 



tion which takes place m moonstone 



— that is, when the inner reflection produces a silvery or bluish light. 

 Whether or no a convenient English form of this term will be made remains to 

 be seen, but Glaukisiren may be translated as the process which produces the 

 silvery schiller or inner reflection. Hitherto the assumption has been that the 

 process was one of internal reflection and interference. The tests made by Viola 

 tend to prove that instead of interference it is a process of absorption. The 

 method followed in examining the moonstone of Ceylon was as follows : 



Ceylon moonstone consists of coarse feldspar crystals, enclosing and inter- 

 grown with quartz. The feldspar is not absolutely definite, but the analyses 

 indicate orthoclase with slight admixture of lime and soda. It is usually milk 

 white in color, and the cleavages are wave-like. The silvery schiller appears to 

 be most marked parallel to the face 201. Sections were therefore cut parallel 

 to this face, and about 1 mm. thick. These were mounted in an ordinary 

 Fuess goniometer with 201 vertical, and the plane of reflection of the schiller 

 (found by experiment to be approximately (010)) horizontal. Parallel light 

 from the collimator, reflected from ^oi as parallel light, gave a sharp signal for 

 the plane ; the section was then revolved until the sky-blue schiller signal was 

 obtained ; this was not sharp, but diffused through four to five degrees, but the 



