204 IOWA ACADEMY OF SCIENCES. 



burn them, and thus create gas, are furnished by Schering & 

 Glatz of New York. H. K. Mulford Co. have also devised a 

 regenerator which converts formaldehyde solution into gas in 

 large quantities so that the work of disinfecting public institu- 

 tions, like schoolrooms and hospital wards, can be done quickly 

 and in a thoroughly satisfactorilly manner. The work of dis- 

 infection should always be under the direction of a physician or 

 some other scientific person who knows how strong the dis- 

 infectant must be in order to surely destroy all of the disease 

 germs. Some skill is also required in order to properly expose 

 carpets, upholstered furniture, books papers, bedding and 

 wearing apparel so that the disinfecting gas may thoroughly 

 penetrate every part of the thing which requires disinfection. 



TREES AND SHRUBS OF HAMILTON COUNTY. 



H. A. MUELLER. 



Hamilton county is the fourth from the north and the sixth 

 county from the Missouri river, thus placing it in the north 

 central portion of Iowa. 



The county is a distinctly prairie country, situated on a level 

 divide between the Des Moines river on the west and Iowa 

 river on the east, neither stream touching the borders of the 

 county. 



The general surface of the county is quite level, dotted here 

 and there with small lakes and ponds. Of late, these depres- 

 ions have been drained and converted into valuable farm land. 

 The only streams of any note within the borders of the county 

 are Boone river in the western and Skunk river in the south- 

 eastern part. The latter stream has its source near the east 

 central portion, flows south, crossing the south line about six 

 miles from the southeast corner. Skunk river has cut a nar- 

 row, shallow channel through the Wisconsin drift plain, and 

 there are no banks worth mentioning. The timber along this 

 stream is limited to an area about ten miles long and about one- 

 fourth mile wide. 



The only hills of any importance in the county are found 

 along the Boone river. This stream enters the county about 



