6 BULLETIN 449, U. S, DEPAETMENT OF AGEICULTUEE. 



Table I shows the resiihs of the tests : 



Table 1. — Comparative efficiency of solution,''; of loashing and haMng soda 



the hoiling temperature. 



Solution. 



Series 1. 



■Washing soda . 



Do 



Do 



Baking soda.. 



Do 



Do 



.Series ?. 



"Washing soda. 



Do 



Do 



Baking soda.. 



Do 



Do 



Series .1. 



Washing soda. 



Do 



Do 



Baking soda.. 



Do 



Do 



Series 4. 



Washing soda . 



Do 



Do 



Baking soda.. 



Do 



Do 



Series 5. 



Washing soda. 



Do 



Do 



Baking soda.. 



Do 



Do 



Series 6. 



Washing soda . 

 Baking soda.. 



Series 7. 



Washing soda 



Do 



Do 



Baking soda.. 



Do 



Do 



Series S. 



Washing soda 



Do 



Do 



Baking soda.. 



Do 



Do 



Time required for 

 cleaning. 



Observed. Average 



Seconds. 

 30 

 10 

 7 

 10 

 10 

 11 



210 

 20 

 15 

 17 

 10 

 9 



150 

 10 



27 

 4 

 8 



Seconds. 



13.5 ll 

 11 I 



4.5 

 2 



7.5 

 4.5 



S 

 12 

 10 



7.5 



Zinc was the aetive metal used in series 1, 2, and 3. 



The exceptionally long time required in the first test of series 2 

 and 3 was due to the ziric becoming corroded; it was necessary 

 to substitute a strip of clean zinc before the tarnish was 

 removed. In such cases the time has been disregarded in. 

 computing the average. 



Aluminum was the active metal used in series 4 to 9, inclusive. 



fin series 7 and 8 a small sheet of very pure aluminum of the 

 [ spun variety was used. 



