12 
BULLETIN 82 . 
throughout the drainage area, the others will not be given in this place 
§ 24. The first two analyses of the Poudre water that I shall 
give ought, perhaps, to be given in the reverse order, but as I in¬ 
tend to give the rest of the analyses in regular order as we go down 
the river, I will not deviate from it in the case of these. The only 
reason which would justify me in doing so would be the fact that, 
in the case of the second analysis I know that at least one-half of 
the water flowing in the river at the time the sample was taken, 
came down the North Fork as flood water, resulting from a heavy 
rain which fell in the mountains of the remoter portions of its 
drainage area. 
§ 25. For the sake of completeness and for subsequent con¬ 
venience of reference I shall give with each chemical analysis the 
sanitary analysis of the sample; but as the latter is of subordinate 
importance in our study, it will follow the chemical analysis. My 
object in this bulletin is not to deal with the potability of the 
waters used for irrigation, but to learn as much as possible about 
the changes that they suffer and how much they add to the fertility 
of the laud, if any, by virtue of the elements of plant food that 
they contain in solution, and incidentally in suspension also. The 
chemical analysis gives us the amount and approximately the char¬ 
acter of the inorganic salts held in solution, and I have adopted the 
ordinary sanitary analysis as the means of determining the various 
forms in which the nitrogen occurs, as well as its total quantity. 
In regard to the chlorin given in the two forms of analysis, it will 
be observed that the amount given by the sanitary analysis is 
slightly higher than that given by the chemical analysis. 
