426 BOTANICAL GAZETTE [JUNE 
filled with the saturated soil and the electrical resistance is taken 
by means of the Wheatstone electrolytic bridge. Correction is 
then made for temperature, 15.5° C. being taken as the standard. 
A further correction for soil texture is made. By a simple cal- 
culation the percentage by weight of water-soluble salts to soil 
can then be determined from the electrical resistance in ohms of 
the soil solution. Hundreds of determinations have been made 
by the Bureau of Soils in which both the electrolytic method and 
the method of chemical analysis have been applied to the same 
sample of soil, in order to determine its content of salts readily 
soluble in water; and these have demonstrated that the former 
method is sufficiently accurate for all purposes of the present 
inquiry.” 
First of all let us consider the salt marsh soils, which are 
inundated at every high tide. Two borings in such soil were 
made on the Massachusetts coast, the first to a depth of 6%™ in 
coarse gravelly sand, standing water being reached at 4-5 a 
The boring was made amid a luxuriant growth of Salicornia her- 
bacea, with some Statice Limonium caroliniana; while Distichlis 
spicata and Suaeda maritima occurred near by. Here the frst.32° 
contained 1.5, and the second 1,4 per cent. of salt. The second 
boring was taken about 89™ farther from the shore. Here stand- 
ing water appeared at a depth of 2-3°™, precluding carrying the 
boring any deeper, and the coarse sand was mixed with some 
silt and considerable vegetable matter. The vegetation consisted 
of Spartina stricta glabra and a species of Fucus, with Salicornia 
herbacea, the latter smaller and less abundant than where the 
first sample’was taken. Salt was present to the extent of 2.6 
per cent. Near Norfolk, Virginia, a 6°™ boring was made in a 
narrow strip of marsh bordering a tidal inlet amid a fine growth 
of Spartina stricta glabra. The soil was a yellow sandy loam to a 
depth of about 4%, below that a blue clay, standing water being 
reached in the’second 3°". Only 0.32 per cent. of salt was found 
here in the first 3°", and 0.29 per cent. in the second, although 
7A sample of salt marsh soil collected in the course of this investigation showed 
by the electrolytic method the presence of 0.30 and by chemical analysis 0.27 per 
cent. of soluble salts. 
