658 Waring ton. — The Effect of Boric Acid and Borax on 
not applied until considerable growth had been made, 0-5 grm. H 3 B 0 3 per pot 
quickly caused signs of poisoning and a marked retardation in growth, the 
plants changing from a healthy green to a yellowish colour, and the leaves 
showing the typical brown margins, o*i grm. H 3 B 0 3 added at this stage, 
however, had only a very slight toxic effect. 
At the close of the experiment there was no apparent difference 
between the plants treated with boric acid at the two stages of growth, 
though the dry and especially the green weights of the latter treated sets 
were slightly lower than those which received the dressing before germina¬ 
tion (Table VI). 
General conclusions. 
(1) Applications of over 1 grm. of boric acid were injurious when 
mixed throughout the soil, though 0-5 grm. proved toxic if applied as a top¬ 
dressing. 
(2) In two instances a possible increase in the green weight was obtained 
with small quantities of H 3 B 0 3 . 
(3) Borax was possibly slightly less toxic than an equivalent amount 
of boric acid. 
Table VII. 
Mean Green and Dry Weights of Broad Beans grown in Pot Culture 
with Boric Acid and Borax containing equivalent Boro71. (Quantities 
given in terms of H 3 B 0 3 .) 
Average of 6 pots. 2 plants per pot. 
Top-dressed immediately after solving, Mar. 18- June 16, 1922. 
Boric Acid. Borax. 
IT. 6 B 0 , per 
pot. 
Green Weight. 
Dry Weight. 
Green Weight. 
Dry Weight. 
grm. 
grm. 
grm. 
grm. 
grm. 
1-0 
76-10 
12-21 
81-80 
12-18 
o -5 
113.61 
18-71 
116-25 
18.31 
0-1 
i. 33 - lS 
21.83 
128-28 
20.59 
0.02 
134*18 
21.05 
129.59 
2 2 -16 
Control 
1 33*43 
2 I -54 
133-43 
21-54 
B. Barley. 
The seed for these pot-culture experiments was the same as that used 
in the water-culture work ; it was graded for each series, three plants being 
grown per pot. 
a. The Effect of adding Various Quantities of Boric Acid to the Soil. 
A wide range of concentrations of H 3 B 0 3 was tried : (a) Mixed through¬ 
out the soil ; ( b ) applied as a top-dressing. 
(a) Boric acid mixed throughout the soil (22J lb.). From the outset 
