634 



SCIENCE. 



[N. S. Vol. XXIII. No. 590. 



4. January 25 : 



35 h. 47 m. 00 3. 15 h. 46 m. 45 a. 



Beginning principal portion 15 

 End principal portion 15 



End 15 



15 15 49 14 



16 IB 50 45 



54 00 15 



Multiplying ratio of both pointers, 10. 

 Period of north-south, component pendulum 

 about 25 seconds, of east-west component pen- 

 dulum about 20 seconds. 



W. F. Wallis, 

 Observer in charge. 



ANALYSIS OF MISSISSIPPI EIVEE SILT. 



On October 13, 1905, there appeared in 

 Science a complete analysis of the water of 

 the Mississippi River, and toward the close 

 of it the author made the statement that the 

 silt from the water sample had been saved and 

 would be subjected to a plant-food analysis 

 at a later date. Such an analysis has now 



seventy-fifth meridian mean civil time, counting 

 tlie hours continuously from midnight to mid- 

 night. 



"The maximum amplitudes of this earthquake 

 were too large to be recorded. The pendulums 

 struck the brushes on both sides. The ampli- 

 tudes given were measured on the trace and are 

 probably much too small. 



been completed and the results are submitted 

 in this article. The methods followed were 

 the ones officially adopted by the Association 

 of Agricultural Chemists, and the results are 

 expressed in percentages of the moisture-free 

 sample. It is to be regretted that the carbonic 

 acid could not be determined, but the lack of 

 material made it impossible: 



Insoluble matter 67.71 



Sol. Si. 0^ 22 



K^O 1.26 



Na.O 0.13 



CaO 1.83 



MgO 1.64 



MnO 0.18 



FeAAl^Os (mostly Al) 17.90 



PA 0.25 



SO3 0.28 



Water and organic matter 7.00 



Total nitrogen 0.15 



Some facts in connection with this analysis 

 are of peculiar interest. In the first place the 

 per cent, of soluble matter is large and the 

 greater part of it is Al. This gives some 

 insight into the origin of the silt. Another 

 noteworthy feature is the large amount of 

 potash and its ratio to the soda. While in 

 eastern soils it is usual for the potash to be in 

 excess of the soda, the proportion seems larger 

 than customary. In western soils the soda is 

 generally in excess of the potash, and this 

 would indicate that the silt analyzed originally 

 came from a semi-arid or humid region. How- 

 ever, considering the analysis as a whole, there 

 would be no question about pronouncing this 

 silt to be an excellent soil. All this plant 

 food is being removed from the land and 

 carried either to the sea or to the mouth of 

 the river. For the sake of argument let us 

 assume that the above analysis represents the 

 average composition of the silt carried by the 

 Mississippi during the entire year. This is 

 doubtless not quite true, but will serve as a 

 basis for some calculations. One estimate of 

 the total amount of silt carried by the Missis- 

 sippi during a year places the figures at 443,- 

 750,000 tons. Assuming this to be true, the 

 following table gives in tons the amount of 

 various substances removed in this silt dur- 

 ing the year: 



