186 STATE BOARD OF AGRICULTURE. 



REPORT OF RESEARCH ASSOCIATE L. H. COOLEDGE 



During the past year I have continued work upon project Adams 3a, which 

 has the following for its object: 



(a) A study of methods in use at the present time for determining the 

 bacteriological conditions of dairy products. 



(b) An attempt to develop new methods where the old are found inadequate. 



(c) A study of bacteriological problems relating to market milk by means 

 of tests developed under (a). 



In addition to the above outline of the project there has been approved 

 during the past year and is under way in co-operation with Professor J. E. 

 Burnett, of the Dairy Husbandry Department another phase. The object of 

 this investigation is to determine the relation of various dairy practices to 

 clean milk production and to find the practical dairy procedures which may 

 be applied at the average dairy farm, with the best results from a sanitary 

 standpoint. 



During the past year the follo^\^ng bulletins covering some of my work 

 have been published by this Station. 



The colorimetric hydrogen-ion determination as a means of studying bio- 

 logical changes in dairy products. Technical Bulletin No. 52, November, 

 1921. 



An experiment in improving the milk supply of a city milk plant. By 

 L. H. Cooledge and O. T. Goodwdn. Special Bulletin 112, November, 1921. 



At the present time two phases of my problems are being studied in co- 

 operation with members of the Dairy Department It is hoped that other 

 phases may be taken up in a similar manner in order to bring a knowledge of 

 bacteriology to bear on dairying to best advantage. 



Work which is well under way includes the following problems : 



The colorimetric hydrogen-ion determination as a means of locating faulty 

 methods at city milk plants. 



The pH test as a means of judging the suitability of milk for cheese making. 



A study of the factors influencing the quality of milk during transportation. 



The pH method as a means of paying for milk on a quality basis. (With 

 Professor Goodwin of the Dairy Department). 



The relation of discarding the fore milk to low bacterial counts in the 

 production of a high grade market milk. (With Professor Burnett, of the 

 Dairy Department.) 



At the suggestion of Mr. Broughton, of the Bureau of Dairying, State De- 

 partment of Agriculture, a study was made of the sanitary conditions sur- 

 rounding the milk supply of Lansing and East Lansing and of Ypsilanti. 

 Mr. Bobbins, city milk inspector of Lansing, Dr. Pillsbury, Health Officer of 

 Ypsilanti, and Mr. Friar, of the Bureau of Dairying, co-operated in this work. 

 The object of the study was to see what could be accomplished in studying a 

 city's milk supply in a limited time, the results to be presented to those inter- 

 ested for criticism and suggestion as a help in making future studies. These 

 reports follow: 



