1900] MICROSCOPICAL JOURNAL 61 



orange gave the most perfect diflFerentiation. The fibrous 

 tissue was thus stained pink, and the nuclei purple. It 

 was in the nuclei, which appeared as minute specks in a 

 delicate fibrous growth, that the colonies appeared. Un- 

 der the one-sixth objective a colony was seen to be made 

 up of grape-like botlies, some of a pale orange, and others 

 of a pale green color, hut under the one-twelfth inch oil 

 immersion the grape-like bodies were seen to be filled 

 with cocci — small round elements — which were about 3 

 microns in diameter. — Knowledge. 



Silica Standards for the Determination of Turbidity in 



Water. 



GEORGE C. WHIPPLE, AND DANIEL D. JACKSON. 

 The subject of the turbidity of water is one that is 

 growing in importance. This importance varies in dif- 

 ferent sections of the country. In New England, where 

 the natural waters are comparatively clear, the terms "very 

 slight," "slight," "distinct," and ''decided," have been 

 used by analysts to express the amount of suspended mat- 

 ter present. These degrees of turbidity have been esti- 

 mated by the appearance of the examples to the eye when 

 viewed toward the light. This mode of expression has 

 been discarded by analysts who have had to deal with the 

 problem of turbidity in connection with sand filtration or 

 the mechanical treatment of waters that have large quan- 

 tities of clay and other foreign matter in suspension. Ex. 

 periments have shown that it is the finely divided sus- 

 pended matter in water that is most difficult to remove 

 by any system of purification, and it happens that these 

 same fine particles have the greatest effect on the tubid- 

 ity of the water. Hence, in questions relating to the fil- 

 tration of water, the amount of coagulant required for 

 clarification, etc., a reliable expression for the actual tur- 

 bidity is more serviceable to the engineer than a knowl- 



