Headden — Silicic Acid in Mountain Streams. 175 



by difference, but an ignition was made in each instance to 

 assure myself that the ignition given is correct within reason- 

 ably close limits. 



The first analysis of Cache a la Poudre water given is of a 

 sample taken above the mouth of the North Eork, on Oct. 3, 

 1902. This point was chosen because there are no tributaries 

 entering above this point whose waters are not wholly gathered 

 witliin and run for their whole course over an area whose sur- 

 face rocks are the metamorphic granites and schists of the 

 region. The sample was taken at a time when the water 

 was perfectly representative of the drainage water of this area. 



The analysis resulted as follows : 



Analysis of Cache a la Poudre Water, Samjjle taken above the Mouth of the 



North Fork. 



Analytical 

 results. 



SiO,....l.. 



S03 



CO, 



CI 



Na,0 



K,0 



CaO 



SrO 



MgO 



Mn O 



Ignition . 



Per 



cent. 



20-871 

 6-928 



20-790 

 3-575 



12-931 

 2-949 



18-741 



trace 

 4-336 

 0-388 

 0-063 



(9-233) 



Sum 100-805 



Oequiv. toCl -805 



Grs. 

 Imp. Gal. 



0-6053 

 0-1946 

 0-6029 

 0-1037 

 0-3750 

 0-0855 

 0-5238 

 trace 

 0-1257 

 0-0113 

 0-0018 

 0-2678 



Per 



Combined. cent. 



CaSO^ 11-782 



CaCO„ 24-781 



M^CO, 



9-063 

 4-325 



K,C03 ..._ 



Na,C03 9-146 



NaCl 5-899 



Na„SiO, 8-772 



0-388 



0-063 



Ignition (9-233) 



FeA^AlA 

 Mn O - 



Sum 



Excess of SiO, 



Total . _ . - 



83-452 

 16-546 



Grs. 

 Imp. Gal. 



0-3417 

 0-7186 

 0-2628 

 0-1254 

 0-2652 

 0-1711 

 0-2544 

 0-0113 

 0-0018 

 0-2678 



0-4798 



99-908 2-8999 



Total. 



00-000 2-8974 



Total solids 2-9 grs. per imp. gal. 



The second sample of which I shall give an analysis was 

 taken July 30, 1902, on which date the river was carrying 

 about double its usual flow for this season. The flow had been 

 300 second feet for the preceding fortnight, to which it' fell 

 again within a few days, bnt at the time the sample was taken 

 the flow was 600 second feet. In this analysis I did not test 

 for either strontia or lithia. 



