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rifyin; A Discussion of the Different Methods of Safeguarding the Water Used for Drinking and Cooking Purposes With Special Reference to the Great Lakes N impression prevails in this ee that we are ahead of European countries in matters of sanitation. In order to contradict this the following quotation is made from an article by Dr. Allen J. Mc- Laughlin, of the public health and marine hospital service: “The excessive prevalence of typhoid fever in the United States has been characterized, and not without reason, as a national disgrace. Certainly that portion of our typhoid prevalence which is due to polluted water sup- plies is preventable, and our failure to prevent does not redound to our credit. -In northern Europe, the 33 principal cities, with an aggregate population of 31,500,000, had an aver- age typhoid rate per 100,000 popula- tion of 6.5 in 1909 and 1910. The 50 largest cities in the United States, with an aggregate population of over 20,000,000, had an average typhoid death rate in 1910 of 25 per 100,000 inhabitants.” Water—Cause of Typhoid Authorities are practically unani- mous in stating that 85 per cent of all typhoid cases are caused’ by water, and they attribute- the remaining 15 per cent to “lack of control” of ty- phoid cases, “ignorance” of those in contact with typhoid cases, “in- sects” and similar factors connected with existing typhoid cases. If these statements are analyzed it is manifest that if the 85 per cent of cases did - not exist then the 15 per cent gen- erated from them would not exist, and, the logical conclusion must be that all typhoid is traceable to water. Aside from water of exceptional softness, the character of water would not be a modern issue were it not for its pathogenic (disease producing) content, for it is now generally ac- knowledged by leading sanitarians and investigators that far from being detrimental both the mineral elements in solution and the harmless. bacterial content of ‘all ordinary water sup- plies are actual advantages; for the former, by replacement, prevents de- mineralization of the human organism, and the latter, by competition, keeps within normal bounds the necessary microbic element in the healthy hu- man system. The water of the Great Lakes havy- ing a wholesome content of mineral salts, it is therefore only the patho- genic organisms which are to be dealt with, and the matter at issue is their destruction. There are a number of features surrounding the practice of water puri- fication, and particularly the methods employed for ascertaining and rating its efficiency, that are so misleading that they are in no small measure responsible for the lack of expected results. Two seem to be predomi- nant: 1. The extraordinarily small vol- ume unit used in measuring bacterial content, the cubic centimeter. 2. The generally accepted permis- sible allowance of organisms in the effluent water. This’ permissible al- lowance is commonly stated at not more than 100 organisms per cubic centimeter at any time while the aver- age should be 20 or under. /Regocctine the first of these fac- tors, while the cubic centimeter may be .the acceptable laboratory unit, it has. no practical bearing upon the everyday use of water by human beings. The ordinary drinking glass in common household use has a con- tent of 8 ounces or somewhat over 236 cubic centimeters. In reducing the cubic centimeter bacterial con- tent. te-*- practical 2 -use; at) “must be multiplied by 236. When this is done, a fair idea may be gained of the number of bacteria that will be -taken into’ the human system in a single glass of water, not to mention the number of glasses of such water the. average individual will consume in the course of a day. With the above in mind even the average permissible contents . of 20 organisms per cubic centi- meter will. at once disclose suf- ficient reason for the failure of puri- fication, especially in times of peril existing in the natural water sup- plies, for it must be remembered that this average permissible bacterial con- tent is a flat statement and covers bacteria of both benign or harmless and pathogenic or disease-producing character. While bacteria per cubic centimeter is a vastly more intelligent and superior method than that of specifying a given per cent of bacterial reduction, nevertheless the number of bacteria stated as permissible is vague espe- cially as there is no distinction made 128 the permissible. number of | By J. Forbes between benign and pathogenic or- ganisms. If it is only intended to cover benign organisms then there is ‘no necessity for limiting the num- ber to 20 or even to 100 for the natural process of breathing takes. in harmless bacteria far in excess: of this number every hour; on the other hand, if it is intended to cover pathogenic organisms then there” should be no organisms permissible. Respecting the commercial guaran- tee of apparatus to remove 98 or evem 99 per cent of the bacteria, much: depends upon the proportion betweem harmless and pathogenic bacteria and. the total number of organisms in the raw water. In matters bacterial the numbers of organisms are so enor- mous that such percentages of elim- ination. as 98 and 99.are mean- ingless. In time of water - borne peril, efficiencies of 99 and even 99,99 per cent fall wide of the mark for it must be remembered that it does not require, under favorable condi- tions, more than a single organism to transmit a dreaded’ disease. Means of Water Purification For . purposes of classification all the present methods of purification may be broadly grouped under two general headings: (a)—Applicative methods. (b)—Conditional methods. Considering the latter, conditional methods may be said to be those in which the complete action of the agent itself is made the sole condi- tion upon which the water under treatment can pass through the appar-- atus, and this too without the inter- vention of any other or extraneous agent. In other words a true condi- tional method is one in which the agent of purification is the motive power which causes the water to pass through the apparatus. An accidental stoppage cf the agent, or a change in the organic burden of the water un- der treatment, therefore, has no effect on the result obtained by the treat- ment. A truly conditional method of wa- ter ‘purification. calls for something more than a mere purifying agent. Thegeagent must possess an active immutable characteristic which may be made use of in producing some physical change, or bringing about