189G THE MICROSCOPE. 93 



error being- eliminated, are both astonishing- and gratify- 

 ing-. 



From a bacteriolog-ical standpoint they prove that a 

 proper!}' constructed and properly manag-ed filter will 

 remove from 98 to 99.84 percent of the ordinary bacteria in 

 water, and that if such bacteria as the bacillus prodig-iosus, 

 which is very similar to the typhoid bacillus, be added to 

 the water in var^nng- proportions, the filter will remove 

 from 99 to 99.993 per cent. The org-anic matter in solution 

 is g-reatly diminished and the water is chemically purified. 



Moreover, the efficiency of the filter instead of diminish- 

 ing- increases with ag^e and use, owing- to the formation of 

 ag-elatinous coating-about each g-rain of sand, which serves 

 to entang-le the bacteria in their prog-ress. 



The rate of filtration may reach five million g-allons 

 daily per acre of filter without impairing- the efficiency. 

 If the surface-clog-g^ing- is properly removed there will be 

 no appreciable difference in the quality of the filtered 

 water during- or after the process of removal. 



Finally, the cost of construction and maintenance of such 

 filters is not so g-reat as was supposed, and is not to be 

 compared with the benefits derived from their use. The 

 one which has been in successful use in the city of Law- 

 rence proves that the plan is practicable in supplying- cities 

 with potable water. It seems to us that the knowledg-e 

 derived from these experiments should be spread abroad 

 and the attention of the municipal authorities called to 

 them.— Medical Record. 



Note on the Permanent Staining of Ringworm Fungus. 

 — H. G. Adamson (Brit. Jour. Dermat.), for the staining- of 

 ring-worm fung-us, combines the caustic potash solution 

 wdth the ordinary staining- method. Dr. Adamson claims 

 that the keratin nature of the horny tissues is lost by the 

 use of the caustic potash, and that decolorization takes 

 place as in non-horny epithelial tissues (Ayn. Med.-Surg. 

 Bull.) The details are as follows: 1. 5-per cent-10-per-cent 

 solution of caustic potash on the slide for ten to thirty 

 minutes. 2. Wash 15 per cent alcohol in water. 3. Dry 



