80 CIRCULAR 9 7 7, U. S. DEPARTMENT OF AGRICULTURE 



A more accurate but more time-consuming method is as follows: 



Proceed as in the first method, but collect the first 5 gallons of used 

 emulsion that runs from the washer in the first container for use in 

 the next treatment. Determine the percentage of M-1960 present in 

 the used emulsion, as follows: 



Collect a 100-ml. sample of the M-1960 in a 100-ml. glass-stoppered 

 graduate and add approximately 28 grams (23-25 cc. measured in a 

 25-ml. graduated cylinder or 3 level tablespoonfuls) of sodium chloride 

 (U. S. P. — common table salt usually contains calcium silicate, which 

 interferes with an exact reading), insert the stopper, and shake 

 vigorously to dissolve the salt. Set aside until the oil and aqueous 

 phases separate (3-5 minutes usually). When the separation is 

 complete, carefully invert the cylinder with the stopper tightly in 

 position and read the volume of the oil phase. This reading is a 

 direct percentage (v/v) of the M-1960. 



After the concentration of the recovered emulsion has been deter- 

 mined, part or all of it may be combined with an additional quantity 

 of M-1960 to make the next treatment. The amounts of recovered 

 emulsion and M-1960 to be used are as follows: 



Prepare the next emulsion by using 

 the following quantities of — 



// the percent concentration of the recovered 



emulsion is — ■ 

 4-5 __ __ _ --_ 



Recovered 

 emulsion 





M- 



1960 



Gallons 

 4 

 4 

 4 

 4 

 4 

 4 

 4 

 5 



Pints 

 1 

 2 

 3 

 4 

 5 

 6 

 7 



Gallons 

 1 

 1 

 1 

 1 



Pints 

 3 



6-7 



8-9 



10-13 



14-15 



16-17 _ _ 



2 

 1 



- 



6 



18-19 



20-21 



5 



4 



After the same emulsion has been used for 6 to 10 treatments, it 

 will usually become dirty, and the entire emulsion should then be 

 discarded. 



For woolen clothing follow the usual washing procedure through 

 the last rinse. Drain the last rinse water from the washer. With 

 the outlet valve to the drain open, roll the washer with the clothing 

 in it for 2 minutes to remove some of the excess water. Close the 

 outlet valve, and with the washer rolling add an emulsion composed 

 of 6% gallons of water and % gallon of M-1960. Koll for 3 minutes. 

 Spin and dry the clothing in the usual manner. 



Do not save the emulsion drained from the washer. Because of 

 selective absorption of M-1960 by wool, the concentration of repellent 

 in the drained emulsion is very low. 



Clothing treated with the repellents discussed herein may be 

 expected to give protection for at least a week of continuous wear 

 unless the repellent is washed out by rain or wading. The clothing 

 should be reimpregnated after each laundering. 



