8 Mr. A. D. Hall and Dr. N. H. J. Miller. [Mar. 30, 



weights of calcium carbonate. It is impossible to eliminate wholly the errors 

 thus introduced, especially in the case of Broadbalk, where the average weights 

 of the 1865 samples are exceptionally low and where the subsoil shows also 

 a good deal of variation. 



In Table IV two estimates have been drawn up for the amounts of calcium 

 carbonate per acre. In the upper set of figures an attempt has been made 



Table IV.— Broadbalk Soils. 



Calcium Carbonate in Lbs. per Acre. 













Bate of loss per acre 













per annum. 



Plot. 



1865. 



1881. 



1893. 



1904. 

















Whole 



1881—1904. 













period. 





Total of 1st and 2nd 9 Inches + a 



fraction of the 3rd 9 Inches, to bring them 





all to the same Total of 5,240,000 Lbs. of Soil per Acre. 







lbs. 



lbs. 



lbs. 



lbs. 



lbs. 



lbs. 



2b 



100,400 



99,300 



94,300 



85,100 



392 



618 



3 



110,800 



105,900 



94,000 



90,200 



528 



683 



5 



118,100 



99,400 



91,100 



80,800 



809* 



809 



6 





90,200 



55,400 



65,200 



1086 



1086 



7 



93,900 



87,200 



65,000 



64,000 



767 



1009 



8 





75,500 



48,300 



49,700 



1122 



1122 



9 



106,000 



109,100 



111,100 



92,700 



341 



713 



10 



97,800 



88,400 



77,500 



68,300 



756 



874 



11 



103,700 



85,100 



75,900 





993 





First 9 Inches only, reckoned as weighing 2,500,000 Lbs. 



2b 



105,000 



94,700 



86,500 



82,000 



590 



552 



3 



113,500 



99,200 



86,200 



82,200 



800 



739 



5 



124,000 



93,700 



83,500 



73,500 



878* 



878 



6 





85,200 



49,500 



58,200 



1174 



1174 



7 



95,500 



79,750 



59,000 



56,200 



1010 



1024 



8 





71,000 



43,200 



44,000 



1174 



1174 



9 



106,000 



99,700 



93,000 



84,000 



564 



683 



10 



102,500 



82,700 



69,000 



61,700 



1045 



913 



11 



109,000 



78,500 



69,000 





1429 





* 1881—1904 only. 



to introduce a correction for the varying thickness of the slice by adding to 

 the weights of calcium carbonate in the first and second depths such a pro- 

 portion of the third depth as would ensure the comparison of an equal weight 

 of soil in all cases. The lower set of figures is based simply upon the per- 

 centage of calcium carbonate in the upper layer of soil, assuming a general 



