Show THE BEST FILTER The Japanese use a porous sandstone sand-stone hollowed in the shape of an egg through which the water pereolatea into a receptacle underneath the Egyptians resort to a similar device the Spaniards ueea porous earthen pot Bu these and other similar con tiivancei can not be thoroughly cleansed after the most thorough rinsing some impurities will remain in the pores of the stone Spongy iron and carferal are open to the eame objection they will answer well for a short time but soon become contaminated contami-nated by pollution retained in their pores Sponge cloth and fell unless un-less cleaned every day or two with kot water well do more harm than good and the average iervantgir will not clean them or any other filter unless under the eye of her miatrees The various forms of filters that are screwed to tho faucet have only to be hastily examined to be discarded discard-ed aa there is not sufficient filtering material in them to be of much utility utili-ty and they very soon become foul and offensive Buck says u There ia no material known which can be in rodnced into the email space of a tapfilter and accomplish any real purfioation of the water which passes through at the crdinary rate of flowThe The various complioated closed filters fil-ters filled with any material which can not be removed for cleansing condemn themselves No amount of pumping water through them at different dif-ferent angle which is at all likely to be used can cleanse them of the impurities im-purities that adhere to tho mass and in the pores of the filtering material used Parkes in hie Manual I of Practical Hygiene says Filters where the material i is cemented up and can not be removed ought to be abandoned altogether The various metal filters in which the water cornea in contact with metallic met-allic surfaces either iron lead tinned iron or zinc are objectionable from their appreciable influence upon theater the-ater retained in them for any considerable con-siderable time Fare blocktin is the least objectionable of any of the metals The aim of most filters is to remove impurities from the water speedily as rapidly as it escapes from the faucet fau-cet Experiment shows that effective filtration can not be aceomplished in this way as the water does not remain re-main long enough in contact with the filtering material used to become purified pur-ified of much that might be removed by slow filtration or percolation through the same appliance Of all the filtering materials mentioned it seems tome that Band and charcoal are the two that accomplish the best refultp and of these vegetable charcoal char-coal is the bestEdwin J Howe M D in Popular Science Monthly |