108 ata JOHN CG. H. MINGAYE. 
away out of the reach of plants, and this can occur when there is 
only 0:05 grammes per litre. Districts therefore in which salt 
appears either in the waters of irrigation or as underground or 
bottom water, cannot support plants in a healthy state; for apart 
from the solvent action of the common salt in warm weather, it 
is carried up by capillary attraction to the upper parts of the soil, 
becoming there concentrated and so directly inimical to life. 
Analyses of soils thus affected show not only a large increase of 
common salt, chlorine, and total ash in the residue, but a decrease 
in potash and sulphuric acid.”—(A. Stood, Chem..Journ. Aug. 
1889.) 
Mr. A. N. Pearson, Government Agricultural Chemist for 
Victoria, in his valuable report to the Secretary for Water Supply 
‘states as follows :—‘ It is known that an excess of common salt 
-and of other chlorides will diminish the Prodan ena of soils. 
Voelcker states as a result of experiment that +3; per cent. of salt 
in a soil makes it absolutely barren, probably the limit varies 
according to many circumstances. The usual dressing of salt as 
an alterative to the soil is about two cwt. per acre ; five cwt. is a 
‘maximum dressing, which should not be given often. Now ifa 
water contains thirty parts of chlorine, which would represent 
about fifty parts of salt in 100,000 parts, one acre of that water 
‘ten inches deep would contain half a ton of galt, which as we have 
seen before is excessive dressing. 
“Tt may be considered that fifteen parts of chlorine per 100,000 
-of water is a safe limit for general irrigation purposes; that a 
water containing more than this should be used sparingly ; and 
‘that one containing forty or fifty should be condemned. 
‘These limits I have fixed upon however only on general con- 
siderations such as above given. [am putting the matter to a 
direct test on a laboratory scale by using solutions of different 
strengths for watering pot plants. It is possible that if a soil 
were deep drained, and occasionally flooded so that an excessive 
accumulation of salt in it could be washed out, a water containing a 
-somewhat high percentage of salt may be used.” (A. N. Pearson.) 
