174 MASS. EXPERIMENT STATION BULLETIN 170. 



as a filling to cover the cavity opeiiiiia;, and some years ago use was made 

 of irregular pieces of untreated wood for filling cavities. However, cement 

 in different forms has been most frequently employed for cavity fillings, 

 and various metals have been used as a covering for the cavity opening, 

 Use has also been made of wire mesh covered with elastic cement; com- 

 binations of asphalt and sawdust; paraffine and sawdust; wood pulp and 

 cement; excelsior and asphalt; sawdust, tar and oakum; certain com- 

 posite substances like papier-mach^; special floor cements; and chemically 

 treated wooden blocks. 



KiG. 40. — Different methods of fasteniog branches. The solid 

 lines represent the best method; dotted lines inferior 

 methods. 



Various disinfectants, such as copper sulfate, corrosive sublimate, 

 Bordeaux mixture, kerosene, formalin, carbolineum, coal tar, creosote, 

 etc., have been employed for cavity work, but some of them are 

 poorly adapted for the purpose. Creosote and carbolineum are similar 

 in nature, and are the best materials for disinfecting cavities. The 

 former apparently possesses greater power of penetration than the latter, 

 although carbolineum seems to form a more permanent external covering 

 than creosote. (See Fig. 26.) Owing to the slow penetration of all dis- 

 infectants into moist wood, more than one treatment is needed, and if 

 the cavity is left open for a while before receiving later treatments, so 

 much the better. 



Although there have been complaints that creosote injures trees, we 

 have never observed any such injury, notwithstanding the fact that we 

 have treated cavities within 1 inch of the vital area. In all instances 



