Feb., 1919] Nitrogen Content of Volcanic Ash 215 



A. P. H. A. Standard Methods of Water x\nalysis, and were 

 carried to the field in small reagent bottles provided with a 

 special device to guard against leakage or contamination. 

 No attempt was made to use a set of standard colors, but each 

 determination was matched against standard solutions. On 

 returning to the laboratory the reagents and standard solutions 

 used on the expedition were checked up, and, in the case of the 

 nitrous nitrogen, a suitable correction for deterioration in the 

 standard solution of sodium nitrite was applied to the observa- 

 tions. A copper still was carried into the field, but fortunately 

 the use of distilled water was obviated by the almost complete 

 absence of ammonia and nitrous nitrogen in the surface and 

 spring waters of the Katmai district. Moreover, the water from 

 melting snow was found to be almost free from these nitrogen 

 compounds. (For a detailed statement of these matters, see 

 the following paper of this series, pages 230-234). 



The samples of ash investigated w^ere air dried on aluminum 

 plates, and 100 grams weighed on a small hand balance. This 

 amount of ash was then placed upon a previously well washed 

 filter paper in a five inch glass funnel, and leached with suc- 

 cessive portions of ammonia and nitrite free water until approxi- 

 mately 150 cubic centimeters of filtrate were obtained. This 

 filtrate was then made up to 150 cubic centimeters and 50 

 cubic centimeter portions used for comparison with the standard 

 solutions. A check on the results was always kept by testing 

 for ammonia 50 cubic centimeters of the last washings of the 

 filter paper previous to adding the ash. It was really surprising 

 how persistently traces of ammonia clung to the filter papers. 

 Moreover the ubiquitous ammonium compounds were con- 

 stantly being met with in the most unexpected quarters, and 

 the greatest care had to be exercised in preventing contamina- 

 tion of the samples collected for analysis. On one occasion 

 several samples of dry ash were carried to camp in ordinary 

 brown paper bags that had not previously been used in any way. 

 Irregularities in the analyses of the ash taken from these bags 

 led to the suspicion that even the dry ash had been contami- 

 nated by contact with them. A water infusion of the paper 

 bags, when treated with Nessler's solution, gave a heavy yellow 

 precipitate of the ammonia complex. Ever afterwards all 

 samples were collected and carried in glass or metal containers 

 previously well freed from ammonium compounds by efficient 

 washing. 



