36 BOTANICAL GAZETTE [SEPTEMBER 
four hours. The volume must not be allowed to decrease while on 
the steam bath. The solution was then filtered off from the 
barium sulphate, washed until no test for chlorides was obtained, 
the precipitate dried in an oven, and ignited to constant weight in a 
muffle furnace. 
Part of the sulphur determinations reported later in this paper 
were obtained by igniting over a microburner, taking care that the 
paper was consumed without flaming up, but it was found that 
more uniformly successful results were obtained by igniting in a 
muffle furnace. 
The iron and aluminum were removed because it was found 
that, in the case of a number of the soils analyzed, the barium 
sulphate precipitate was quite seriously contaminated by the iron. 
In the case of some of the soils analyzed during the preliminary 
work, the iron collected in masses on the bottom of the beaker. 
In other cases there was no contamination, or so little that the 
error introduced was small. It was decided, however, to make it 
a general practice to remove the iron and aluminum before adding 
the barium chloride solution. The chief difficulty encountered 
in the process was in washing out the sulphate ion from the iron 
and aluminum hydroxides. By using hot water, however, and 
having the precipitate well separated with paper pulp, the sulphate 
ion was completely washed out. It was found that there was some 
sulphur in the reagents used. Blanks were run and correction 
made for this. 
The phosphorus was determined by the magnesium nitrate 
method as given in the Methods of Analysis of the Association of 
Official Agricultural Chemists (17). No important modification 
was made in the method. The ignition value given is the loss 
in weight obtained by heating the soil in the muffle furnace at 
red heat for an hour and a half. Two or three grams were used, 
and it was found that after heating for this length of time there 
was no loss of weight on further heating. 
Data 
In the following results of the analyses, the samples that proved 
to have the lowest sulphur content will be given first. The chief 
