UTAH ACADEMY OF SCIENCES 93 
when in the younger stage of growth than it does after 
it reaches the five-leaf stage. 
An experiment with seedling plants shows the aver- 
age order of toxicity for the different treatments to be 
sodium carbonate, sodium chloride, magnesium chloride, 
calcium chloride and sodium sulphate; sodium carbonate 
being most harmful and sodium sulphate least. Solu- 
tions containing less than 60,000 parts per million of 
sodium chloride apparently stimulated dry matter pro- 
duction in seedling plants. 
Sodium chloride was slightly more toxic to growth 
in height of seedlings than other salts and sodium sul- 
phate distinctly favored this development. Highly con- 
centrated solutions of these salts tended to reduce the 
height of the plant. With the weaker strengths of alkali, 
plants withstood sodium chloride better than sodium car- 
bonate, but when the stronger solution was applied the 
plants were killed at an earlier stage with sodium chloride 
than with sodium carbonate. Plants were apparently 
little injured at the end of the three weeks when grow- 
ing in a soil watered with a 200,000 parts per million 
solution of sodium sulphate, the highest strength tried. 
The action of alkali on plants does not seem to become 
manifest immediately after the salts are added to the soil 
in the form of alkali solutions. 
For seedling plants toxicity of a single irrigation 
with a solution of alkali salts, when based on an average 
of the erectness of the plants, wilting of the leaves, brown- 
ing and corroding of the base of the stems, and the gen- 
eral healthfulness of the plants, was first apparent at a 
strength of 0.3125 molecules or where the soils contained 
about 1,800 parts per million of sodium chloride 3,300 
parts per million of sodium carbonate or 4,400 of sodium 
sulphate. Sodium carbonate was most harmful in these 
strengths followed by sodium chloride and sodium sul- 
phate. The unmixed salts or those diluted only slightly 
by the other two salts appeared more toxic than where 
all three salts were somewhat more equally mixed. 
Mixtures of sodium carbonate and sodium chloride were 
as toxic as either salt alone and in some cases more so, 
especially where there was a marked toxic effect of the 
salts. The condition of the plants was reduced to less 
