8 
Colorado Experiment Station 
haps, necessary, to give a few to give the reader an idea of the 
richness of some of these soils in nitrates and to present the 
I>eculiarities in the composition of the mass of soluble salts 
present in the soils. 
DIFFICULTIES IN ANALYZING EXRTAOTS 
The difficulties met with in making these analyses are 
serious enough to justify mention of the fact in the text and 
not relegate it to a foot-note. We have found it necessary in 
other publications to state that the analyses had been calculated 
to one hundred. This has never meant that the determination 
of any constituent had been omitted but usually that owing to 
the organic matter and the nature of the salts present the errors 
were distributed. The determination of the organic matter was 
considered the least reliable and of the least importance and 
was, therefore, bracketed or rejected. 
The analysis of an ordinary alkali may not be either an 
important or a high grade piece of work, still it may prove to 
be a difficult matter, not to make it add up to 100 with only an 
allowable deviation, but to make the acids and bases balance. 
It is a ver>^ common experience to find that the bases are in ex- 
cess of the amount required by the acids present, and a repe- 
tition of the whole analysis will probably fail to change this 
result. If there are chlorids of calcium and magnesium or ni- 
trates of these elements present, it is possible that basic salts 
may be formed on evaporation, and drying at a higher temp- 
erature is out of the question. In manipulating these soil ex- 
tracts I have frequently found it impossible to obtain a solid 
residue without easily perceptible decomposition of the nitrates. 
This difficulty has proven so great that in some cases we have 
used the aqueous extract of the soil without concentration which 
presents other difficulties. Evaporation under reduced ])ress- 
ure was not feasible. 
It is fortunate that in this work a slight misstatement in 
regard to the absolute quantities of the respective salts pre- 
sent or their relative proportions does not conceal, or seriously 
distort the main facts. If the question had to be decided by 
any narrow margin in the quantity or so nice an adjustment 
of the relations that the errors iiilrodiic(Ml by Ibis nninuM' 
of treating the results became important, the question i'self 
would disappear. The facts themselves are so big and e video) t 
