SAP-STAIN, MOLD, AND DECAY IN GREEN WOOD. 



47 



EXPERIMENTAL DIPPING OF KED-OAK BLOCKS AT THE LABOKATOKY OF FOREST 

 PATHOLOGY, MADISON, WIS. 



A comparison of the specific antiseptic values of the chemical sub- 

 stances employed in the spoke-dipping experiments can hardly be 

 made, since these substances were not used in solutions of uniform 

 strength. To determine, if possible, the comparative values of these 

 and several other common antiseptics and preservatives in the control 

 of mold and sap-stain 

 fungi, several series 

 of experiments were 

 undertaken at the 

 Madison laboratory. 

 AVhere possible, solu- 

 tions were made up 

 to a calculated value 

 of 1 per cent actual 

 weight of anhydrous 

 salt. The hygroscopic 

 substances — sodium 

 chlorid, calcium 

 chlorid, and glyc- 

 erin — were added in 

 certain instances to 

 determine whether or not they would increase the efficiency of the 

 preservative by keeping the surface of the treated wood moist. A 

 list of the substances used follows : 



Fig. 21. — Storage of spokes in a warehouse. The truck 

 spokes at the left have just been painted by girls with 

 a resin-linseed oil mixture to prevent checking. 



Alum (potassium). 

 Ammonium fluorid. 

 Bleaching powder. 

 Borax. 



Copper sulphate. 

 Lead acetate. 

 Lead nitrate. 

 Magnesium silicofluorid. 

 Mercuric chlorid. 

 Mercuric chlorid and hydro- 

 chloric acid, 1 per cent. 



Potassium chlorate. 



Sodium fluorid. 



Sodium bifluorid. 



Zinc silicofluorid. 



Creosote in kerosene. 



Formalin. 



Lysol. 



Mykantin. 



Orthonitrophenol. 



Rongalite. 



Red-oak blocks f by f by 1^ inches long, sawed from the sapwood 

 of summer-cut logs, were used in each case. Ten blocks constituted 

 a group. The individual blocks of a group were immersed for ap- 

 proximately 10 seconds in one of the respective solutions, drained, 

 and then sprayed on all six sides with a water suspension of the 

 spores taken from the same cultures as those used in the steaming 

 experiments.^* The sprayed blocks of each group were then close 

 piled and placed in the tile chamber mentioned on page 29. An in- 



^ See page 29 for the list of fungi. 



