69 



has joined with the laboratories of the State Boards of 

 Health of Michigan, Wisconsin, Indiana, and the Health De- 

 partment Laboratory of Chicago, in a comparative analysis 

 of Lake Michigan water. It has also made a special study 

 of methods of determining nitrogen as nitrates, a test which 

 is of great importance as a sanitary test for Illinois waters. 



Under the second division. Diagnostic, are included the 

 large number of analyses made at the request of the health 

 officers or other citizens to determine the character of waters. 

 The Survey is working in conjunction with the State Board 

 of Health in endeavoring to prevent and check epidemics of 

 water-borne diseases. In 1908, 1862 samples of water were 

 sent in by people not connected with the Survey staff, and a 

 large proportion of the time of the active staff has been occu- 

 pied with this work. Because of the great demand for work 

 of this kind the Trustees of the University have recently 

 passed a resolution concerning the work of this class to be 

 done by the Water Survey, which is summarized as fol- 

 lows : 



"The State Water Survey will make a sanitary analysis 

 free of charge of any water from the State of Illinois, when 

 there is any suspicion that there is danger to health. 



"The Water Survey will make sanitary and mineral analyses 

 free of charge of any present or proposed municipal water 

 supply. 



"A fee will be charged for the examination of the mineral 

 content of waters, other than municipal supplies. This in- 

 cludes analyses to determine the medicinal value, and to de- 

 termine the character of a water with reference to its use 

 in boilers or for manufacturing purposes." 



Under the third division, Education and Publicity, the 

 Survey issues bulletins describing the work done. Lectures 

 are given to communities on problems connected with water 

 supplies. Water-works men have taken and can take advantage 

 of the Water Survey Laboratories to learn methods of chemical 

 or bacteriological control for their water-works plants. 



The Survey should examine every water-works plant in 



