404 BOTANICAL GAZETTE [MAY 
crops for the past twelve years. Particular attention must be given 
to the samples from Paris, Illinois. Part of this field had been an 
old orchard where alfalfa had never been grown before. When 
the hay was ready to be harvested, parts of the field showed a differ- 
ence in color, some being yellow and others being dark green. 
These samples when analyzed showed a marked chemical difference, 
as shown in the tables. 
Several methods of sulphur determinations were tried before 
satisfactory results warranted the adoption of any particular one. 
The peroxide method as described in the Agricultural Chemists 
Bulletin no. 107 was finally adopted. The Osborn method caused 
a great deal of trouble by the igniting or foaming over of the material 
near the completion of the first fusion. This may have been due 
to too rapid heating of the crucible. This difficulty was better 
controlled in the official method because of the presence of sodium 
carbonate, which slowed down the reaction. The carbonate also 
caused some trouble at first in removing the residue from the 
crucible. This, however, was overcome by allowing a small stream 
of water to play on the residue after it had cooled just enough to 
prevent spattering. When the crucible was filled with water the 
material came out very easily. This treatment ruined the crucible 
in a very short time, but it shortened the process considerably. 
There were two distinct crucial periods in the process. The 
first was when the sodium peroxide began to break down the 
material and ammonia was being liberated. This was the most 
critical because of the flashing which caused the loss of many 
determinations. Samples varied considerably in the flashing, 
perhaps owing to the different amounts of nitrate present. The 
second critical point occurred in the slow heating after the addition 
of the first 10 gm. of peroxide. The flame had to be regulated and 
the stirring so constant that the reaction did not become violent 
enough to burn up the sample or cause it to foam over the top. 
When these conditions were carefully controlled, the solutions 
were clear when neutralized, and the results obtained from a series 
of duplicate samples agreed as well as could be expected. 
The dry fusion method is severely criticized by KocH (STOCK- 
HOLM 13) because not all the sulphur is secured by this method. 
