PREFACE 



At present it is necessary for those expecting to become 

 housewives to understand the elementary phases of a number 

 of sciences, most prominent among which are chemistry and 

 bacteriology. The relation of microorganisms to household 

 affairs is now felt to be one of the most important phases 

 of domestic science. The present work is designed for all 

 interested in household affairs, including not only students 

 in domestic science but all housewives who are interested in 

 keeping their homes in the best and most healthful condition. 



The present (third) edition has been quite largely revised 

 in order to bring the subject up to date. The principal 

 changes made relate to refrigeration, canning, and the spread 

 of disease. The book has further been changed by adding 

 a historical introduction in order to give the student an idea 

 of the historical setting of the subject and at the same time 

 to introduce it in a way to arouse as much interest as possible. 



