The student of Sanitary Chemistry should ever bear in mind that the Water Analyst almost invariably has a complex problem to solve in the case of every sample of water submitted to him for examination. He is called upon to answer the following questions 1. Is the water in question potable 2. If not, what is the trouble 3. Is it possible to form an opinion as to the future quality of the water 4. Can the water be improved in quality, and how 5. Does the water contain constituents rendering it unsatisfactory or undesirable for general household or municipal use 6. Is the water suitable for general industrial purposes It is thus essential that the analyst shall have clearly before hirn these questions that he may so obtain his samples and so plan his analyses as to enable him to form an opinion and properly advise his client. The conlplete data necessary for the formation of a reliable opinion as to the fitness or desirability of a water for a municipal or household water supply and to properly answer the above questions may be grouped under the following heads. I. HISTORY OF THE SAMPLE-its source the geography and geology of the surrounding country. This we may term environnental data. 11. PHSICAL EXAMINATION. , Temperature Appearance Turbidity sediment and suspended matter Color Odor Taste l. Sitrogen content in ammoniacal salts or compounds, in albuminoid or protein-like material, and in the form of oxidized nitrogen, or in other words Nitrogen as Free Ammonia or Saline Ammonia Nitrogen as Albuniinoid Ammonia Nitrogen as Nitrites Nitrogen as Nitrates Nitrogen as Total Organic Nitrogen 2. Organic Matter as shown by the quantity of oxygen required to oxidize the material in solution this value is termed oxygen consumed and is expressed in parts per inillion of oxygen used...