ERADICATING THE COMMON BARBERRY 15 
As shown in Table 1, the first six treatments were made by piling 
the salt in a ring around the base of the plants. No difference could 
be observed in the effectiveness of this method on the bushes cut down 
and on those left standing. On comparison with treatments made 
with sodium chloride on the same day and in the same manner the 
following differences were noted : Of the 40 bushes receiving 5 pounds 
each of calcium chloride, only 40 per cent were killed, whereas the 
corresponding sodium-chloride treatment killed 75 per cent of the 
bushes. With 10 pounds of the chemical to the bush, calcium chloride 
killed 80 per cent and sodium chloride 97% per cent; and with 15 
pounds, 721/2 and 97% per cent, respectively, were killed. 
Before the treatment made on July 10, 1922, it had become evident 
that the treatments were more effective when the chemicals were 
piled in the base of the plant than when placed in a circle around the 
base. This method was followed in the remaining treatments, and 
on account of the poor showing made by calcium chloride in the 
earlier treatments, a 15-pound application was made. As shown by 
the table, this failed to kill all of the 80 bushes treated. 
Calcium chloride is very hygroscopic. When shipped it is usually 
packed in tins or in paper-lined sacks to exclude moisture. When 
the containers are opened moisture is absorbed rapidly by the chem- 
ical, and it becomes wet and sticky. In handling, much of the 
chemical adheres to the clothes and hands and makes the operation 
very disagreeable. Although this in itself should not condemn a 
chemical that otherwise may be satisfactory, it should be taken 
into consideration. 
It may be that this hygroscopic character of calcium chloride is 
accountable for the poor showing it made in comparison with sodium 
chloride. It was noticed that when the latter was piled around a 
barberry bush in the quantities used in this work it usually was 
several months before it all dissolved, whereas calcium chloride 
usually dissolved completely in a few days. The action of calcium 
chloride on vegetation other than the barberry was very similar to 
that of sodium chloride. Grass and weeds near the treated spot 
were killed and occasional shrubs were injured. Its sterilizing ac- 
tion on the soil did not continue for so long a period, however. 
FERROUS SULPHATE 
Ferrous sulphate (FeS0 4 .7H 2 0) has been used for many years 
as a herbicide, especially for killing young weeds in grain fields and 
in grass plots. Although it was known to be a mild herbicide, there 
was a possibility that it might be specific for barberries. It was 
therefore tried out in the greenhouse. Doses as large as 10 grams 
dissolved in 1-00 cubic centimeters of water failed to kill small bar- 
berries growing in 8-inch pots. On account of this, unsatisfactory 
showing of ferrous sulphate as compared with some of the other 
chemicals field tests were not made. 
MERCURIC CHLORIDE 
Mercuric chloride (HgCl 2 ) also was tried out in the greenhouse, 
but with unsatisfactory results; consequently no field tests were 
made. With small barberries in 8-inch pots, 6 grams of mercuric 
chloride in 200 cubic centimeters of water failed to produce death. 
