86 Journal of Agricultural Research vol. xx, no. 2 



The term "Dakin's solution" as used in this paper signifies a neutral 

 solution of sodium hypochlorite. The methods of preparation were 

 essentially those given by Dakin and Dunham (5). 



The details of the method with sodium carbonate are, according to 

 Dakin and Dunham, as follows: One hundred and forty gm. of dry 

 sodium carbonate (Na 2 C0 3 ), or 400 gm. of the crystallized salt, are dis- 

 solved in 10 liters of water, and 200 gm. of bleaching powder containing 

 24 to 28 per cent of "available chlorin" are added. The mixture is very 

 thoroughly shaken, and after it has stood half an hour the supernatant 

 fluid is siphoned off from the precipitate and filtered through a cotton 

 plug or through paper. Forty gm. of boric acid are added to the filtrate, 

 and it is then ready for use. 



The details of the method with sodium carbonate and sodium bicarbo- 

 nate are, according to Dakin and Dunham, as follows: Two hundred 

 gm. of bleaching powder (containing 24 to 28 per cent of "available 

 chlorin") are shaken well with 5 liters of water and allowed to stand 

 for an hour or two. In a separate vessel 94 gm. of sodium carbonate 

 and 86 gm. of sodium bicarbonate (NaHC0 3 ) are mixed with 5 liters 

 of water, and this solution is added to the bleaching powder suspension. 

 The mixture is well shaken and allowed to stand until the precipitate 

 settles. The clear supernatant fluid is then siphoned off and filtered. 



In actual practice the writer made the following modifications. The 

 amount of Dakin's solution made up at any one time was always smaller 

 than the amount indicated above, but the relative proportions of ingre- 

 dients were the same. The bleaching powder was rubbed up in a mortar 

 with a little water until it was of a creamy consistency. It was then 

 transferred to a graduated flask or cylinder and made up to volume with 

 more water. Dry sodium carbonate, or the solution of sodium carbonate 

 and sodium bicarbonate, was added in accordance with the directions of 

 Dakin and Dunham, and their further directions were followed except 

 that instead of the clear supernatant fluid being drawn off the entire 

 mixture was shaken up and filtered through paper. The bleaching pow- 

 der used contained approximately 28 per cent of "available chlorin." 



In certain experiments Dakin's solution was also prepared by the 

 direct action of chlorin upon a solution of sodium carbonate, with the 

 use of the apparatus devised for the purpose by the Wallace & Tiernan 

 Co., of New York City. 



The term " eusol, " as employed in this paper, signifies a solution pre- 

 pared from bleaching powder in aqueous solution by the addition of an 

 equal amount of boric acid. The originators of this solution (12) de- 

 scribe it as a solution of hypochlorous acid, but according to Dakin and 

 Dunham (5) the solution is alkaline to litmus and contains a balanced 

 mixture of calcium hypochlorite and calcium borate with an undeter- 

 mined amount of free hypochlorous acid. 



