boards of health and milk inspectors in some of the larger cities and 

 towns are beginning systematic inspections and insisting that the 

 stables of the producers be kept clean and well ventilated, that the 

 cows be kept free from filth and fed on suitable food, and that the 

 product be so handled as to render it clean and safe for human con- 

 sumption. The investigation reported in the following pages was 

 undertaken for the purpose of ascertaining as nearly as possible the 

 chemical and bacteriological composition of market milk within a 

 given area, as well as the conditions governing its production. 



The area canvassed comprised the country supplying Amherst and 

 Northampton, and is probably quite representative of the conditions 

 existing in the cities and towns of Massachusetts where no milk is 

 brought from a distance by rail. Before describing the investigation 

 proper, it has seemed wise to devote a few pages to the character and 

 composition of normal milk, in order that the reader may have a 

 comprehensive idea of the subject under consideration. 



PART I. 



CHARACTER, COMPOSITION AND FOOD VALUE OF 



MILK. 



Properties of Normal milk is an opaque, almost white 



Milk. fluid, nearly free from germ life when first 



drawn from the udder. The lack of trans- 

 parency is due partly to the fat held in suspension and partly 

 to a suspension of the nitrogenous and mineral matter. It has a 

 slight smell and a mild sweetish taste. When allowed to stand for 

 any length of time, a multitude of fat globules rise to the surface and 

 form what is termed cream. On continuous standing, the sugar of 

 milk is converted by bacteria into lactic acid, and the milk coagu- 

 lates or sours. 



The larger part of milk consists of water. 



Ingredients of which contains a variety of substances in sus- 



Milk. pension and solution. The substances largely 



dissolved in the water are casein and albumen, 



milk sugar, and the ash or mineral matter, which together form the 



